Peer-reviewed Publications |
Barosch, J., Nittler L.R., Wang, J., Alexander, C. O. 'D., De Gregorio, B. T., Engrand, C., Kebukawa, Y., Nagashima, K., Stroud, R. M., & Yabuta, H., et al. (2022). Presolar Stardust in Asteroid Ryugu. ApJL, 935, L3.
Résumé: We have conducted a NanoSIMS-based search for presolar material in samples recently returned from C-type asteroid Ryugu as part of JAXA's Hayabusa2 mission. We report the detection of all major presolar grain types with O- and C-anomalous isotopic compositions typically identified in carbonaceous chondrite meteorites: 1 silicate, 1 oxide, 1 O-anomalous supernova grain of ambiguous phase, 38 SiC, and 16 carbonaceous grains. At least two of the carbonaceous grains are presolar graphites, whereas several grains with moderate C isotopic anomalies are probably organics. The presolar silicate was located in a clast with a less altered lithology than the typical extensively aqueously altered Ryugu matrix. The matrix-normalized presolar grain abundances in Ryugu are ${4.8}{-2.6}^{+4.7}$ ppm for O-anomalous grains, ${25}{-5}^{+6}$ ppm for SiC grains, and ${11}{-3}^{+5}$ ppm for carbonaceous grains. Ryugu is isotopically and petrologically similar to carbonaceous Ivuna-type (CI) chondrites. To compare the in situ presolar grain abundances of Ryugu with CI chondrites, we also mapped Ivuna and Orgueil samples and found a total of 15 SiC grains and 6 carbonaceous grains. No O-anomalous grains were detected. The matrix-normalized presolar grain abundances in the CI chondrites are similar to those in Ryugu: ${23}{-6}^{+7}$ ppm SiC and ${9.0}_{-3.6}^{+5.4}$ ppm carbonaceous grains. Thus, our results provide further evidence in support of the Ryugu–CI connection. They also reveal intriguing hints of small-scale heterogeneities in the Ryugu samples, such as locally distinct degrees of alteration that allowed the preservation of delicate presolar material.
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Boulet, C., & Ma, Q. (2022). Line coupling and line mixing effects on calculated widths of symmetric-top molecules with the k-degeneracy: A theoretical study of N2-, O2-, and air-broadened lines of CH3I. Journal of Quantitative Spectroscopy and Radiative Transfer, 288, 108273.
Résumé: Calculations of the N2-, O2-, and air-broadened widths, together with their temperature dependence exponents have been made for transitions of CH3I in the ν5 and ν6 bands. The calculations are based on a semi-classical line shape formalism developed by the current authors through modifying and refining the Robert-Bonamy formalism. In recent years, we have applied this formalism for linear molecules, symmetric-top molecules with inversion symmetry, and asymmetric-top molecules. For symmetric-top molecules with the k degeneracy such as CH3I, the formalism has a new feature. In this case, one should consider each of the CH3I transitions labeled by ki or f ≠ 0 as a doublet. Then, one needs to consider the effects of the line mixing process between these two components. Comparisons of our theoretical predictions with some data available demonstrate a very reasonable agreement. Finally we propose new experiments at higher perturber pressures that would enable one to check the theoretically calculated relaxation matrices and to extend the analysis to the inter-doublet mixing effects.
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Buntine, J. T., Carrascosa, E., Bull, J. N., Jacovella, U., Cotter, M. I., Watkins, P., Liu, C., Scholz, M. S., Adamson, B. D., Marlton, S. J. P., & Bieske, E. J. (2022). An ion mobility mass spectrometer coupled with a cryogenic ion trap for recording electronic spectra of charged, isomer-selected clusters. Review of Scientific Instruments, 93, 043201.
Résumé: Infrared and electronic spectra are indispensable for understanding the structural and energetic properties of charged molecules and clusters in the gas phase. However, the presence of isomers can potentially complicate the interpretation of spectra, even if the target molecules or clusters are mass-selected beforehand. Here, we describe an instrument for spectroscopically characterizing charged molecular clusters that have been selected according to both their isomeric form and their mass-to-charge ratio. Cluster ions generated by laser ablation of a solid sample are selected according to their collision cross sections with helium buffer gas using a drift tube ion mobility spectrometer and their mass-to-charge ratio using a quadrupole mass filter. The mobility- and mass-selected target ions are introduced into a cryogenically cooled, three-dimensional quadrupole ion trap where they are thermalized through inelastic collisions with an inert buffer gas (He or He/N2 mixture). Spectra of the molecular ions are obtained by tagging them with inert atoms or molecules (Ne and N2), which are dislodged following resonant excitation of an electronic transition, or by photodissociating the cluster itself following absorption of one or more photons. An electronic spectrum is generated by monitoring the charged photofragment yield as a function of wavelength. The capacity of the instrument is illustrated with the resonance-enhanced photodissociation action spectra of carbon clusters (Cn+) and polyacetylene cations (HC2nH+) that have been selected according to the mass-to-charge ratio and collision cross section with He buffer gas and of mass-selected Au+2 and Au2Ag+ clusters.
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Buntine, J. T., Carrascosa, E., Bull, J. N., Muller, G., Jacovella, U., Glasson, C. R., Vamvounis, G., & Bieske, E. J. (2022). Photo-induced 6π-electrocyclisation and cycloreversion of isolated dithienylethene anions. Phys. Chem. Chem. Phys., 24, 16628–16636.
Résumé: The diarylethene chromophore is commonly used in light-triggered molecular switches. The chromophore undergoes reversible 6π-electrocyclisation (ring closing) and cycloreversion (ring opening) reactions upon exposure to UV and visible light, respectively, providing bidirectional photoswitching. Here, we investigate the gas-phase photoisomerisation of meta- (m) and para- (p) substituted dithienylethene carboxylate anions (DTE−) using tandem ion mobility mass spectrometry coupled with laser excitation. The ring-closed forms of p-DTE− and m-DTE− are found to undergo cycloreversion in the gas phase with maximum responses associated with bands in the visible (λmax ≈ 600 nm) and the ultraviolet (λmax ≈ 360 nm). The ring-open p-DTE− isomer undergoes 6π-electrocyclisation in the ultraviolet region at wavelengths shorter than 350 nm, whereas no evidence is found for the corresponding electrocyclisation of ring-open m-DTE−, a situation attributed to the fact that the antiparallel geometry required for electrocyclisation of m-DTE− is energetically disfavoured. This highlights the influence of the carboxylate substitution position on the photochemical properties of DTE molecules. We find no evidence for the formation in the gas phase of the undesirable cyclic byproduct, which causes fatigue of DTE photoswitches in solution.
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Chen, N. L., Gans, B., Hartweg, S., Garcia, G. A., Boyé-Péronne, S., & Loison, J. - C. (2022). Photoionization spectroscopy of the SiH free radical in the vacuum-ultraviolet range. The Journal of Chemical Physics, 157(1), 014303.
Résumé: The first measurement of the photoelectron spectrum of the silylidyne free radical, SiH, is reported between 7 and 10.5 eV. Two main photoionizing transitions involving the neutral ground state, X+ 1Σ+ ← X 2 Π and a+ 3Π ← X 2 Π, are assigned by using ab initio calculations. The corresponding adiabatic ionization energies are derived, IEad (X+ 1Σ+ ) = 7.934(5) eV and IEad (a+ 3Π) = 10.205(5) eV, in good agreement with our calculated values and the previous determination by Berkowitz et al. [J. Chem. Phys. 86, 1235 (1987)] from a photoionization mass spectrometric study. The photoion yield of SiH recorded in this work exhibits a dense autoionization landscape similar to that observed in the case of the CH free radical [Gans et al., J. Chem. Phys. 144, 204307 (2016)].
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Chitarra, O., Pirali, O., Spaniol, J. - T., Hearne, T. S., Loison, J. - C., Stanton, J. F., & Martin-Drumel, M. - A. (2022). Pure Rotational Spectroscopy of the CH2CN Radical Extended to the Sub-Millimeter Wave Spectral Region. The Journal of Physical Chemistry A, 126(41), 7502–7513.
Résumé: We present a thorough pure rotational investigation of the CH2CN radical in its ground vibrational state. Our measurements cover the millimeter and sub-millimeter wave spectral regions (79–860 GHz) using a W-band chirped-pulse instrument and a frequency multiplication chain-based spectrometer. The radical was produced in a flow cell at room temperature by H abstraction from acetonitrile using atomic fluorine. The newly recorded transitions of CH2CN (involving N″ and Ka″ up to 42 and 8, respectively) were combined with the literature data, leading to a refinement of the spectroscopic parameters of the species using a Watson S-reduced Hamiltonian. In particular, the A rotational constant and K-dependent parameters are significantly better determined than in previous studies. The present model, which reproduces all experimental transitions to their experimental accuracy, allows for confident searches for the radical in cold to warm environments of the interstellar medium.
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Coudert, L. H., Chitarra, O., Spaniol, J. - T., Loison, J. - C., Martin-Drumel, M. - A., & Pirali, O. (2022). Tunneling motion and splitting in the CH2OH radical: (Sub-)millimeter wave spectrum analysis. The Journal of Chemical Physics, 156, 244301.
Résumé: The (sub-)millimeter wave spectrum of the non-rigid CH2OH radical is investigated both experimentally and theoretically. Ab initio calculations are carried out to quantitatively characterize its potential energy surface as a function of the two large amplitude ∠H1COH and ∠H2COH dihedral angles. It is shown that the radical displays a large amplitude torsional-like motion of its CH2 group with respect to the OH group. The rotation–torsion levels computed with the help of a 4D Hamiltonian accounting for this torsional-like motion and for the overall rotation exhibit a tunneling splitting, in agreement with recent experimental investigations, and a strong rotational dependence of this tunneling splitting on the rotational quantum number Ka due to the rotation–torsion Coriolis coupling. Based on an internal axis method approach, a fitting Hamiltonian accounting for tunneling effects and for the fine and hyperfine structure is built and applied to the fitting of the new (sub)-millimeter wave transitions measured in this work along with previously available high-resolution data. 778 frequencies and wavenumbers are reproduced with a unitless standard deviation of 0.79 using 27 parameters. The N = 0 tunneling splitting, which could not be determined unambiguously in the previous high-resolution investigations, is determined based on its rotational dependence.
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Dartois, E., Chabot, M., Koch, F., Bachelet, C., Bender, M., Bourçois, J., Duprat, J., Frereux, J., Godard, M., Hervé, S., Merk, B., Pino, T., Rojas, J., Schubert, I., & Trautmann, C. (2022). Desorption of polycyclic aromatic hydrocarbons by cosmic rays. A&A, 663, A25.
Résumé: Context. The rate of sputtering and release of condensed species is an important aspect of interstellar chemistry, as is photodesorption for the most volatile species, because in the absence of such mechanisms the whole gas phase would have to condense in times often shorter than the lifetime of the considered medium, in particular for dense clouds. The recent detection of cyclic aromatic molecules by radioastronomy requires an understanding of the potential mechanisms supporting the rather high abundances observed.
Aims. We perform experiments to advance our understanding of the sputtering yield due to cosmic rays for very large carbonaceous species in the solid phase.
Methods. Thin films of perylene and coronene were deposited on a quartz cell microbalance and exposed to a 1.5 MeV N+ ion beam at the Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab, Orsay, France) and a 230 MeV 48Ca10+ ion beam at the GSI Helmholtzzentrum für Schwerionenforschung (GSI, Darmstadt, Germany). The mass loss was recorded as a function of the fluence for the N+ beam. The microbalance response was calibrated using Fourier transform infrared (FTIR) reflectance measurements of the produced films. In addition, the destruction cross-section of the same species was measured with the 48Ca10+ ion beam by in situ monitoring of the evolution of the infrared spectra of the bombarded films.
Results. We deduced the sputtering yield for perylene and coronene and their radiolysis destruction cross-sections. Combining these results with a cosmic ray astrophysical spectrum, we discuss the impact on the possible abundance that may originate from the sputtering of dust grains with these molecules as well as from polycyclic aromatic molecules when they are trapped in ice mantles.
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Dartois, E., Noble, J. A., Ysard, N., Demyk, K., & Chabot, M. (2022). Influence of grain growth on CO2 ice spectroscopic profiles. A&A, 666, A153.
Résumé: Context. Interstellar dust grain growth in dense clouds and protoplanetary disks, even when moderate, affects the observed interstellar ice profiles as soon as a significant fraction of dust grains are in the size range close to the wave vector at the considered wavelength. The continuum baseline correction made prior to analysing ice profiles influences the subsequent analysis and hence the estimated ice composition, which are typically obtained by band fitting using thin film ice mixture spectra.
Aims. We explore the effect of grain growth on the spectroscopic profiles of ice mantle constituents, focusing particularly on carbon dioxide, with the aim of understanding how it can affect interstellar ice mantle spectral analysis and interpretation.
Methods. Using the discrete dipole approximation for scattering and absorption of light, the mass absorption coefficients of several distributions of grains – composed of ellipsoidal silicate cores with water and carbon dioxide ice mantles – are calculated. A few models also include amorphous carbon in the core and pure carbon monoxide in the ice mantle. We explore the evolution of the size distribution starting in the dense core phase in order to simulate the first steps of grain growth up to three microns in size. The resulting mass absorption coefficients are injected into RADMC-3D radiative transfer models of spherical dense core and protoplanetary disk templates to retrieve the observable spectral energy distributions. Calculations are performed using the full scattering capabilities of the radiative transfer code. We then focus on the particularly relevant calculated profile of the carbon dioxide ice band at 4.27 µm.
Results. The carbon dioxide anti-symmetric stretching mode profile is a meaningful indicator of grain growth. The observed profiles towards dense cores obtained with the Infrared Space Observatory and Akari satellites already show profiles possibly indicative of moderate grain growth.
Conclusions. The observation of true protoplanetary disks at high inclination with the James Webb Space Telescope should present distorted profiles that will allow constraints to be placed on the extent of dust growth. The more evolved the dust size distribution, the more the extraction of the ice mantle composition will require both understanding and taking grain growth into account.
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Drozdovskaya, M. N., Coudert, L. H., Margulès, L., Coutens, A., Jørgensen, J. K., & Manigand, S. (2022). Successive deuteration in low-mass star-forming regions: The case of D2-methanol (CHD2OH) in IRAS 16293-2422. A&A, 659, A69.
Résumé: Context. Di-deuterated molecules are observed in the earliest stages of star formation at abundances of a few percent relative to their nondeuterated isotopologs, which is unexpected considering the scarcity of deuterium in the interstellar medium. With sensitive observations leading to the detection of a steadily increasing number of di-deuterated species, it is becoming possible to explore successive deuteration chains.
Aims. The accurate quantification of the column density of di-deuterated methanol is a key piece of the puzzle that is missing in the otherwise thoroughly constrained family of D-bearing methanol in the deeply embedded low-mass protostellar system and astrochemical template source IRAS 16293-2422. A spectroscopic dataset for astrophysical purposes was built for CHD2OH and made publicly available to facilitate the accurate characterization of this species in astrochemical surveys.
Methods. The newly computed line list and partition function were used to search for CHD2OH toward IRAS 16293-2422 A and B in data from the Atacama Large Millimeter/submillimeter Array (ALMA) Protostellar Interferometric Line Survey (PILS). Only nonblended, optically thin lines of CHD2OH were used for the synthetic spectral fitting.
Results. The constructed spectroscopic database contains line frequencies and strengths for 7417 transitions in the 0–500 GHz frequency range. ALMA-PILS observations in the 329–363 GHz range were used to identify 105 unique, nonblended, optically thin line frequencies of CHD2OH for synthetic spectral fitting. The derived excitation temperatures and column densities yield high D/H ratios of CHD2OH in IRAS 16293-2422 A and B of 7.5 ± 1.1% and 7.7 ± 1.2%, respectively.
Conclusions. Deuteration in IRAS 16293-2422 is not higher than in other low-mass star-forming regions (L483, SVS13-A, NGC 1333-IRAS2A, -IRAS4A, and -IRAS4B). Di-deuterated molecules consistently have higher D/H ratios than their mono-deuterated counterparts in all low-mass protostars, which may be a natural consequence of H–D substitution reactions as seen in laboratory experiments. The Solar System’s natal cloud, as traced by comet 67P/Churyumov–Gerasimenko, may have had a lower initial abundance of D, been warmer than the cloud of IRAS 16293-2422, or been partially reprocessed. In combination with accurate spectroscopy, a careful spectral analysis, and the consideration of the underlying assumptions, successive deuteration is a robust window on the physicochemical provenance of star-forming systems.
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Fakhardji, W., Boulet, C., Tran, H., & Hartmann, J. - M. (2022). Direct calculations of the CH4+CO2 far infrared collision-induced absorption. Journal of Quantitative Spectroscopy and Radiative Transfer, 283, 108148.
Résumé: We present computations, solely using input data from the literature and thus free of any adjusted parameter, of the far infrared collision-induced absorption (CIA) by interacting CH4 and CO2 molecules. They are based on classical molecular dynamics simulations (CMDS) of the rotational and translational motions of the molecules made using an accurate ab initio CH4-CO2 anisotropic intermolecular potential, and on a long-range expansion of the interaction-induced dipole. Various desymmetrization procedures, which all ensure detailed balance of the spectral density function are a posteriori applied to the CMDS results. The comparison with the available measurements, which have been collected at room temperature, show that a good agreement can be obtained without introducing any ad hoc short-range dipole components, and it enables to point out the limits of some of the desymmetrization procedures. Tests are also made of the so-called “isotropic approximation”, which point out its strong limits, since it leads to large underestimations of the CIA, and question previous computations made using an isotropic potential and long-range expansion of the induced dipole complemented by ad hoc contributions at short distances. Finally, the temperature dependence of the CIA is predicted for applications to planetary atmospheres.
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Genossar, N., Changala, P. B., Gans, B., Loison, J. - C., Hartweg, S., Martin-Drumel, M. - A., Garcia, G. A., Stanton, J. F., Ruscic, B., & Baraban, J. H. (2022). Ring-Opening Dynamics of the Cyclopropyl Radical and Cation: the Transition State Nature of the Cyclopropyl Cation. Journal of the American Chemical Society, 144(40), 18518–18525.
Résumé: We provide compelling experimental and theoretical evidence for the transition state nature of the cyclopropyl cation. Synchrotron photoionization spectroscopy employing coincidence techniques together with a novel simulation based on high-accuracy ab initio calculations reveal that the cation is unstable via its allowed disrotatory ring-opening path. The ring strains of the cation and the radical are similar, but both ring opening paths for the radical are forbidden when the full electronic symmetries are considered. These findings are discussed in light of the early predictions by Longuet-Higgins alongside Woodward and Hoffman; we also propose a simple phase space explanation for the appearance of the cyclopropyl photoionization spectrum. The results of this work allow the refinement of the cyclopropane C–H bond dissociation energy, in addition to the cyclopropyl radical and cation cyclization energies, via the Active Thermochemical Tables approach.
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Harper, O. J., Chen, N. L., Boyé-Péronne, S., & Gans, B. (2022). Pulsed-Ramped-Field-Ionization ZEro-Kinetic-Energy PhotoElectron Spectroscopy: a methodological advance. Phys. Chem. Chem. Phys., 24, 2777.
Résumé: A new experimental method has been developed to record photoelectron spectra based on the well-established pulsed-field-ionization zero-kinetic-energy photoelectron spectroscopy technique and inspired by the data treatment employed in slow photoelectron spectroscopy. This method has been successfully applied to two well-known systems: the X+2Πg, 1/2 (v+=0) ← X 1Σ+g (v=0) and the X+1Σ+ (v+=2) ← X 2Π1/2 (v=0) ionizing transitions of CO2 and NO, respectively. The first results highlight several advantages of our technique such as an improved signal-to-noise ratio without degrading the spectral resolution and a direct field-free energy determination. The data obtained for NO indicate that this method might be useful for studying field-induced autoionization processes.
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Hearne, T. S., Mammez, M. - H., Mammez, D., Martin-Drumel, M. - A., Roy, P., Pirali, O., Eliet, S., Barbieri, S., Hindle, F., Mouret, G., & Lampin, J. - F. (2022). Unlocking synchrotron sources for THz spectroscopy at sub-MHz resolution. Opt. Express, 30(5), 7372–7382.
Résumé: Synchrotron radiation (SR) has proven to be an invaluable contributor to the field of molecular spectroscopy, particularly in the terahertz region (1-10 THz) where its bright and broadband properties are currently unmatched by laboratory sources. However, measurements using SR are currently limited to a resolution of around 30 MHz, due to the limits of Fourier-transform infrared spectroscopy. To push the resolution limit further, we have developed a spectrometer based on heterodyne mixing of SR with a newly available THz molecular laser, which can operate at frequencies ranging from 1 to 5.5 THz. This spectrometer can record at a resolution of 80 kHz, with 5 GHz of bandwidth around each molecular laser frequency, making it the first SR-based instrument capable of sub-MHz, Doppler-limited spectroscopy across this wide range. This allows closely spaced spectral features, such as the effects of internal dynamics and fine angular momentum couplings, to be observed. Furthermore, mixing of the molecular laser with a THz comb is demonstrated, which will enable extremely precise determinations of molecular transition frequencies.
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Jacovella, U., Buntine, J. T., Cotter, M., Muller, G., Scholz, M. S., & Dartois, E. (2022). On the possible contribution of cationic oxygenated carbon chains CnO+, HCnO+, and OCnO+ (n = 4 − 9) to the diffuse interstellar bands. Mon Not R Astron Soc, 511(4), 5171–5179.
Résumé: Only 4 of the diffuse interstellar bands (DIBs) are currently accounted for, ascribed to electronic transitions of C_{60}^+. Investigations into carriers of other DIBs historically focus on charged and neutral hydrocarbons, and little information is available regarding oxygenated carbon and hydrocarbon species that result from the two most abundant heavy elements in the interstellar medium, C and O. In this study, we assess whether CnO+, HCnO+, and OCnO+ (n = 4 − 9) cations are viable candidates to account for DIBs using both density-functional theory (DFT) and coupled cluster single-double and perturbative triple theory, CCSD(T). For these species, the linear structures are the most stable isomers with the lowest dissociation threshold corresponding to CO loss. Optical absorptions of the oxygenated carbon chain cations are characterized by calculated vertical excitation wavelengths and their corresponding oscillator strengths using the equation-of-motion CCSD (EOM-CCSD) method. Aside from HC4O+ and HC2n + 1O+, all of the species considered in this study have calculated electronic transitions that lie in the visible or near-infrared spectral regions. Minimal column densities necessary for these cations to account for DIBs have been estimated. Based on present results and the known column densities for neutral oxygenated carbon chains in TMC-1, the growth rate of charged O-bearing carbon chains via ion-neutral reaction mechanisms is judged to be too low to form a sufficient population to give rise to DIBs.
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Jacovella, U., Hansen, C. S., Giuliani, A., Trevitt, A. J., & Nahon, L. (2022). UV/VUV photo-processing of protonated N-hetero(poly)acenes. Mon Not R Astron Soc, 511(4), 5656–5660.
Résumé: N-heterocycles are suspected to play an important role in the chemical origin of life. Despite their detection in meteorites and in Titan’s atmosphere, their extra-terrestrial chemical formation networks remain elusive. Furthermore N-heterocyclics are undetected in the interstellar medium. This paper assesses the photostability of protonated N-hetero(poly)acenes after UV and VUV excitation. It provides information on their ability to retain the N atom into the cycle to generate larger N-containing species or functionalized N-heterocyles. Protonated N-hetero(poly)acenes were generated using electrospray ionization and injected into a linear ion trap where they were irradiated by radiation of 4.5 to 10 eV using the DESIRS beamline at the synchrotron SOLEIL. The photodissociation action spectra of protonated pyridine, quinoline, isoquinoline, and acridine were measured by recording the photofragment yields as a function of photon energy. The four systems exhibit dissociation channels associated with H2 and HCN/HNC loss but with different branching ratios. The results indicate that increasing the size of the N-hetero(poly)acenes increases the chance of retaining the N atom in the larger fragment ion after photodissociation but it remains that all the protonated N-hetero(poly)acenes studied lose their N atom at part of a small neutral photofragment, with high propensity. Therefore, protonated N-hetero(poly)acenes in interstellar space are unlikely precursors to form larger N-containing species. However, protonated pyridine, quinoline, isoquinoline, and acridine are most likely to retain their N atoms in planetary atmospheres where UV radiation at the planet’s surface is typically restricted to wavelengths greater than 200 nm – suggesting such environments are possible substrates for prebiotic chemistry.
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Jacovella, U., Noble, J. A., Guliani, A., Hansen, C. S., Trevitt, A. J., Mouzay, J., Couturier-Tamburelli, I., Pietri, N., & Nahon, L. (2022). Ultraviolet and vacuum ultraviolet photo-processing of protonated benzonitrile (C6H5CNH+). A&A, 657, A85.
Résumé: Context. The recent detection in pre-stellar sources of cyano-substituted and pure hydrocarbon cycles has emphasized the importance of aromatic chemistry in the earliest stages of star formation. Ultraviolet (UV) and vacuum-UV (VUV) radiation is ubiquitous in space and thus the photo-processing of small cyclic ions may open a window onto rich chemical networks and lead to the formation of larger aromatics in space.
Aims. The aim is to investigate the fate of protonated benzonitrile species after UV and VUV photoexcitation and the subsequent potential impact on stellar and interstellar chemistry.
Methods. Protonated benzonitrile was isolated in a linear ion trap prior to irradiation with UV and VUV radiation (4.5–13.6 eV) from the DESIRS beamline at synchrotron SOLEIL. The study was extended down to 3.5 eV using a cryogenic Paul ion trap coupled to an OPO laser at the PIIM laboratory. Photodissociation action spectra were obtained by monitoring the photofragment yields as a function of photon energy.
Results. The UV/VUV photodissociation action spectra of protonated benzonitrile show structured bands from 3.8 to 9 eV. The primary dissociation channel of protonated benzonitrile corresponds to HCN/HNC loss and formation of the phenylium cation (C6H5+); whereas at high energies, a minor channel is observed that correlates with HC3N loss and formation of C4H5+.
Conclusions. The UV and VUV photodestruction of protonated benzonitrile leads to the formation of a highly reactive cationic species, C6H5+, predicted to be an important precursor of larger aromatic molecules in space, such as polycyclic aromatic hydrocarbons. The inclusion of C6H5+ – a precursor of benzene and, by extension, of benzonitrile – as the result of formation via the photodissociation of protonated benzonitrile in current astrochemical models could improve the predicted abundance of benzonitrile, which is currently underestimated.
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Kerraouch, I., Kebukawa, Y., Bischoff, A., Zolensky, M. E., Wölfer, E., Hellmann, J. L., Ito, M., King, A., Trieloff, M., Barrat, J. - A., Schmitt-Kopplin, P., Pack, A., Patzek, M., Hanna, R. D., Fockenberg, T., Marrocchi, Y., Fries, M., Mathurin, J., Dartois, E., Duprat, J., Engrand, C., Deniset, A., Dazzi, A., Kiryu, K., Igisu, M., Shibuya, T., Wakabayashi, D., Yamashita, S., Takeichi, Y., Takahashi, Y., Ohigashi, T., Kodama, Y., & Kondo, M. (2022). Heterogeneous nature of the carbonaceous chondrite breccia Aguas Zarcas – Cosmochemical characterization and origin of new carbonaceous chondrite lithologies. Geochimica et Cosmochimica Acta, 334, 155–186.
Résumé: On April 23rd, 2019, the Aguas Zarcas meteorite fall occurred in Costa Rica. Because the meteorite was quickly recovered, it contains valuable extraterrestrial materials that have not been contaminated by terrestrial processes. Our X-ray computed tomography (XCT) and scanning electron microscopy (SEM) results on various pre-rain fragments from earlier work (Kerraouch et al., 2020; 2021) revealed several distinct lithologies: Two distinct metal-rich lithologies (Met-1 and Met-2), a CM1/2 lithology, a C1 lithology, and a brecciated CM2 lithology consisting of different petrologic types. Here, we further examined these lithologies in the brecciated Aguas Zarcas meteorite and report new detailed mineralogical, chemical, isotopic, and organic matter characteristics. In addition to petrographic differences, the lithologies also display different chemical and isotopic compositions. The variations in their bulk oxygen isotopic compositions indicate that the various lithologies formed in different environments and/or under diverse conditions (e.g., water/rock ratios). Each lithology experienced a different hydration period during its evolution. Together, this suggests that multiple precursor parent bodies may have been involved in these processes of impact brecciation, mixing, and re-assembly. The Cr and Ti isotopic data for both the CM1/2 and Met-1 lithology are consistent with those of other CM chondrites, even though Met-1 displays a significantly lower ε50Ti isotopic composition that may be attributable to sample heterogeneities on the bulk meteorite scale and may reflect variable abundances of refractory phases in the different lithologies of Aguas Zarcas. Finally, examination of the organic matter of the various lithologies also suggests no strong evidence of thermal events, but a short-term heating cannot completely be excluded. Raman parameters indicate that the peak temperature has been lower than that for Yamato-793321 (CM2, ∼400 °C). Considering the new information presented in this study, we now better understand the origin and formation history of the Aguas Zarcas daughter body.
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Mammez, M. - H., Buchanan, Z., Pirali, O., Martin-Drumel, M. - A., Turut, J., Ducournau, G., Eliet, S., Hindle, F., Barbieri, S., Roy, P., Mouret, G., & Lampin, J. - F. (2022). Optically Pumped Terahertz Molecular Laser: Gain Factor and Validation up to 5.5 THz. Adv. Photonics Res., 3(4), 2100263.
Résumé: Quantum cascade laser-pumped terahertz (THz) gas lasers are at the edge of revolutionizing THz science where powerful yet tunable sources have long been lacking. Maybe one of the last remaining drawbacks to a wider use of these instruments lies in the lack of available databases of potentially lasing transitions for users. A new figure of merit, the molecular gain?factor is proposed, that allows to discriminate transitions by their lasing potential. Using this factor, catalogs of THz laser lines of ammonia, both 14NH3 and 15NH3, up to 10?THz are reported. Demonstration of the use of these two catalogs, and of the pertinence of the molecular gain?factor, is made by experimentally observing 32 laser lines of 14NH3 and 5 lines of 15NH3 up to 5.5?THz. Prospects to generalize the use of this molecular gain?factor to a wide range of molecules are discussed.
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Marlton, S. J. P., Buntine, J. T., Liu, C., Watkins, P., Jacovella, U., Carrascosa, E., Bull, J. N., & Bieske, E. J. (2022). Disentangling Electronic Spectra of Linear and Cyclic Hydrogenated Carbon Cluster Cations, C2n+1H+ (n = 3–10). The Journal of Physical Chemistry A, 126(38), 6678–6685.
Résumé: Electronic spectra are measured for protonated carbon clusters (C2n+1H+) containing between 7 and 21 carbon atoms. Linear and cyclic C2n+1H+ isomers are separated and selected using a drift tube ion mobility stage before being mass selected and introduced into a cryogenically cooled ion trap. Spectra are measured using a two-color resonance-enhanced photodissociation strategy, monitoring C2n+1+ photofragments (H atom loss channel) as a function of excitation wavelength. The linear C7H+, C9H+, C11H+, C13H+, C15H+, and C17H+ clusters, which are predicted to have polyynic structures, possess sharp 11Σ+ ← X̃1Σ+ transitions with well-resolved vibronic progressions in C–C stretch vibrational modes. The vibronic features are reproduced by spectral simulations based on vibrational frequencies and geometries calculated with time-dependent density functional theory (ωB97X-D/cc-pVDZ level). The cyclic C15H+, C17H+, C19H+, and C21H+ clusters exhibit weak, broad transitions at a shorter wavelength compared to their linear counterparts. Wavelengths for the origin transitions of both linear and cyclic isomers shift linearly with the number of constituent carbon atoms, indicating that in both cases, the clusters possess a common structural motif.
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Mathurin, J., Deniset-Besseau, A., Bazin, D., Dartois, E., Wagner, M., & Dazzi, A. (2022). Photothermal AFM-IR spectroscopy and imaging: Status, challenges, and trends. Journal of Applied Physics, 131, 010901.
Résumé: This article focuses on the atomic force microscopy-infrared (AFM-IR) technique and its recent technological developments. Based on the detection of the photothermal sample expansion signal, AFM-IR combines the high spatial resolution of atomic force microscopy with the chemical identification capability of infrared spectroscopy to achieve submicrometric physico-chemical analyses. Since the first publication in 2005, technological improvements have dramatically advanced the capabilities of AFM-IR in terms of spatial and spectral resolution, sensitivity, and fields of applications. The goal of this paper is to provide an overview of these developments and ongoing limitations. We summarize recent progress in AFM-IR implementations based on the major AFM contact, tapping, and peak force tapping modes. Additionally, three new trends are presented, namely, AFM-IR applied to mineral samples, in fluid and a novel, purely surface sensitive AFM-IR configuration, to probe top layers. These trends demonstrate the immense potential of the technique and offer a good insight into the scope of AFM-IR.
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PI Team:, Berné, O., Habart, É., Peeters, E., Core Team:, Abergel, A., Bergin, E. A., Bernard-Salas, J., Bron, E., Cami, J., Dartois, E., Fuente, A., Goicoechea, J. R., Gordon, K. D., Okada, Y., Onaka, T., Robberto, M., Röllig, M., Tielens, A. G. G. M., Vicente, S., Wolfire, M. G., Extended Core Team:, Alarcón, F., Boersma, C., Canin, A., Chown, R., Dicken, D., Languignon, D., Le Gal, R., Pound, M. W., Trahin, B., Simmer, T., Sidhu, A., Van De Putte, D., One-time co-authors contributed to SEPs, Cuadrado, S., Guilloteau, C., Maragkoudakis, A., Schefter, B. R., Schirmer, T., Collaborators:, Cazaux, S., Aleman, I., Allamandola, L., Auchettl, R., Antonio Baratta, G., Bejaoui, S., Bera, P. P., Bilalbegović, G., Black, J. H., Boulanger, F., Bouwman, J., Brandl, B., Brechignac, P., Brünken, S., Burkhardt, A., Candian, A., Cernicharo, J., Chabot, M., Chakraborty, S., Champion, J., Colgan, S. W. J., Cooke, I. R., Coutens, A., Cox, N. L. J., Demyk, K., Donovan Meyer, J., Engrand, C., Foschino, S., García-Lario, P., Gavilan, L., Gerin, M., Godard, M., Gottlieb, C. A., Guillard, P., Gusdorf, A., Hartigan, P., He, J., Herbst, E., Hornekaer, L., Jäger, C., Janot-Pacheco, E., Joblin, C., Kaufman, M., Kemper, F., Kendrew, S., Kirsanova, M. S., Klaassen, P., Knight, C., Kwok, S., Labiano, Á., Lai, T. S. - Y., Lee, T. J., Lefloch, B., Le Petit, F., Li, A., Linz, H., Mackie, C. J., Madden, S. C., Mascetti, J., McGuire, B. A., Merino, P., Micelotta, E. R., Misselt, K., Morse, J. A., Mulas, G., Neelamkodan, N., Ohsawa, R., Omont, A., Paladini, R., Elisabetta Palumbo, M., Pathak, A., Pendleton, Y. J., Petrignani, A., Pino, T., Puga, E., Rangwala, N., Rapacioli, M., Ricca, A., Roman-Duval, J., Roser, J., Roueff, E., Rouillé, G., Salama, F., Sales, D. A., Sandstrom, K., Sarre, P., Sciamma-O’Brien, E., Sellgren, K., Shannon, M. J., Shenoy, S. S., Teyssier, D., Thomas, R. D., Togi, A., Verstraete, L., Witt, A. N., Wootten, A., Ysard, N., Zettergren, H., Zhang, Y., Zhang, Z. E., & Zhen, J. (2022). PDRs4All: A JWST Early Release Science Program on Radiative Feedback from Massive Stars. Publications of the Astronomical Society of the Pacific, 134(1035), 054301.
Résumé: Massive stars disrupt their natal molecular cloud material through radiative and mechanical feedback processes. These processes have profound effects on the evolution of interstellar matter in our Galaxy and throughout the universe, from the era of vigorous star formation at redshifts of 1–3 to the present day. The dominant feedback processes can be probed by observations of the Photo-Dissociation Regions (PDRs) where the far-ultraviolet photons of massive stars create warm regions of gas and dust in the neutral atomic and molecular gas. PDR emission provides a unique tool to study in detail the physical and chemical processes that are relevant for most of the mass in inter- and circumstellar media including diffuse clouds, proto-planetary disks, and molecular cloud surfaces, globules, planetary nebulae, and star-forming regions. PDR emission dominates the infrared (IR) spectra of star-forming galaxies. Most of the Galactic and extragalactic observations obtained with the James Webb Space Telescope (JWST) will therefore arise in PDR emission. In this paper we present an Early Release Science program using the MIRI, NIRSpec, and NIRCam instruments dedicated to the observations of an emblematic and nearby PDR: the Orion Bar. These early JWST observations will provide template data sets designed to identify key PDR characteristics in JWST observations. These data will serve to benchmark PDR models and extend them into the JWST era. We also present the Science-Enabling products that we will provide to the community. These template data sets and Science-Enabling products will guide the preparation of future proposals on star-forming regions in our Galaxy and beyond and will facilitate data analysis and interpretation of forthcoming JWST observations.
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Sathanikan, A., Ceccone, G., Bañuls-Ciscar, J., Pan, M., Kamal, F., Bsaibess, T., Gaucher, A., Prim, D., Méallet-Renault, R., Colpo, P., Amigoni, S., Guittard, F., & Darmanin, T. (2022). A bioinspired approach to fabricate fluorescent nanotubes with strong water adhesion by soft template electropolymerization and post-grafting. Journal of Colloid and Interface Science, 606(1), 236–247.
Résumé: Hypothesis
In this original work, we aim to control both the surface wetting and fluorescence properties of extremely ordered and porous conducting polymer nanotubes prepared by soft template electropolymerization and post-grafting. For reaching this aim, various substituents of different hydrophobicity and fluorescence were post-grafted and the post-grafting yields were evaluated by surface analyses. We show that the used polymer is already fluorescent before post-grafting while the post-grafting yield and as a consequence the surface hydrophobicity highly depend on the substituent.
Experiments
Here, we have chosen to chemically grafting various fluorinated and aromatic substituents using a post-grafting in order to keep the same surface topography. Flat conducting polymer surfaces with similar properties have been also prepared for determining the surface energy with the Owens-Wendt equation and estimating the post-grafting yield by X-ray Photoemission Spectroscopy (XPS) and Time of Flight Secondary Emission Spectrometry (ToF-SIMS). For example, using fluorinated chains of various length (C4F9, C6F13 and C8F17), it is demonstrated that the surface hydrophobicity and oleophobicity do not increase with the fluorinated chain length due to the different post-grafting yields and because of the presence of nanoroughness after post-grafting.
Findings
These surfaces have high apparent water contact angle up to 130.5° but also strong water adhesion, comparable to rose petal effect even if there are no nanotubes on petal surface. XPS and ToF-SIMS analyses provided a detailed characterisation of the surface chemistry with a qualitative classification of the grafted surfaces (F6 > F4 > F8). SEM analysis shows that grafting does not alter the surface morphology. Finally, fluorescence analyses show that the polymer surfaces before post-treatment are already nicely fluorescent. Although the main goal of this paper was and is to understand the role of surface chemistry in tailoring the wetting properties of these surfaces rather than provide specific application examples, we believe that the obtained results can help the development of specific nanostructured materials for potential applications in liquid transport, or in stimuli responsive antimicrobial surfaces.
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Si, Y., Grazon, C., Clavier, G., Audibert, J. - F., Sclavi, B., & Méallet-Renault, R. (2022). FRET-mediated quenching of BODIPY fluorescent nanoparticles by methylene blue and its application to bacterial imaging. Photochemical & Photobiological Sciences, 21, 1249–1255.
Résumé: High resolution and a good signal to noise ratio are a requirement in cell imaging. However, after labelling with fluorescent entities, and after several washing steps, there is often an unwanted fluorescent background that reduces the images resolution. For this purpose, we developed an approach to remove the signal from extra-cellular fluorescent nanoparticles (FNPs) during bacteria imaging, without the need for any washing steps. Our idea is to use methylene blue to quench > 90% of the emission of BODIPY-based fluorescent polymer nanoparticle by a FRET process. This “Hide-and-Seek Game” approach offers a novel strategy to apply fluorescence quenching in bioimaging to improve image accuracy.
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Tamassia, F., Bizzocchi, L., Melosso, M., Martin-Drumel, M. - A., Pirali, O., Pietropolli Charmet, A., Canè, E., Dore, L., Gordon, I. E., Guillemin, J. - C., Giuliano, B. M., Caselli, P., Alessandrini, S., Barone, V., & Puzzarini, C. (2022). Synchrotron-based far-infrared spectroscopy of HC3N: Extended ro-vibrational analysis and new line list up to 3360 cm−1. Journal of Quantitative Spectroscopy and Radiative Transfer, 279, 108044.
Résumé: The far-infrared spectrum of HC3N has been recorded at high resolution between 70 and 500 cm−1using synchrotron radiation. Four prominent features, i.e., ν7, ν6−ν7, ν4−ν6, and 2ν7 have been identified in the spectrum together with many associated hot bands. In addition, rotational transitions for the interacting v4=v7=1, (v6=2,v7=1), (v5=1,v7=2), and v7=5 vibrationally excited states have been recorded in the millimeter/submillimeter region. The newly assigned transitions, together with those reported previously, form a comprehensive data set including about 17 000 transitions, which involves almost all the vibrational states of HC3N lying below 1300 cm−1 plus some excited states with energies between 2075 and 3550 cm−1. These data have been fitted to an effective Hamiltonian which takes into account rotational and vibrational l-type resonance effects, together with a number of anharmonic interaction terms. On average, all the analysed data are reproduced within the experimental accuracy. About 90 000 rotational and ro-vibrational transition frequencies have been computed on the basis of the spectroscopic constants obtained from the global fit in order to support data interpretation and astronomical searches in the interstellar medium and planetary atmospheres. Part of these data is included in the 2020 release of the HITRAN database.
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Thébault, P., Ammoun, M., Boudjemaa, R., Ouvrard, A., Steenkeste, K., Bourguignon, B., & Fontaine-Aupart, M. - P. (2022). Surface functionalization strategy to enhance the antibacterial effect of nisin Z peptide. Surf. Interfaces, 30, 101822.
Résumé: One of the main challenges when building antibacterial surfaces with antimicrobial peptides (AMPs) is to preserve their antimicrobial activity after stable immobilization of the peptides. Among all parameters, order/conformation of self-assembled monolayers, used as spacer, is one the most important. Herein we report the covalent immobilization of the nisin Z peptide on a gold surface functionalized with a self-assembled monolayer of 11-mercaptoundecanoic acid (MUA) alone or mixed with 6-mercaptohexanol, used as a spacer. The MUA acid is activated by treatment with carbodiimide/N-hydroxysuccinimidine and then reacts with nisin Z to form amide bonds via the N terminal part of the peptide. We have characterized each step of the surface modification using X-ray photoelectron spectroscopy, FTIR-ATR spectroscopy and contact angle measurements. The combined results show the success of each functionalization step. Additionally, SFG brings information on the orientation and conformational ordering of the self-assembled monolayers. Indeed, a better order of MUA25 layers compared to MUA was observed due to the spacing of carboxylic acid groups. The antibacterial activity of the immobilized AMPs against Staphylococcus aureus is evaluated using confocal microscopy and bacterial counting: it increases with a better order of the SAMs rather than a greater peptide concentration. This study provides fundamental insights on how to engineer AMPs and substrate to produce efficient biocidal surfaces.
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Ural, M. S., Dartois, E., Mathurin, J., Desmaële, D., Collery, P., Dazzi, A., Deniset-Besseau, A., & Gref, R. (2022). Quantification of drug loading in polymeric nanoparticles using AFM-IR technique: a novel method to map and evaluate drug distribution in drug nanocarriers. Analyst, 147, 5564–5578.
Résumé: Researchers are increasingly thinking smaller to solve some of the biggest challenges in nanomedicine: the control of drug encapsulation. Although recent years have witnessed a significant increase in the development and characterization of polymeric drug nanocarriers, several key features are still to be addressed: Where is the drug located within each nanoparticle (NP)? How much drug does each NP contain? Is the drug loading homogeneous on an individual NP basis? To answer these questions, individual NP characterization was achieved here by using atomic force microscopy-infrared spectroscopy (AFM-IR). A label-free quantification methodology was proposed to estimate with a nanoscale resolution the drug loadings of individual poly(lactic acid) (PLA) NPs loaded with an anticancer drug. First, a drug loading calibration curve was established using conventional IR microspectroscopy employing PLA/drug homogeneous films of well-known compositions. Then, single NPs were investigated by AFM-IR acquiring both IR mappings of PLA and drug as well as local IR spectra. Besides, drug location within single NPs was unravelled. The measured drug loadings were drastically different (0 to 21 wt%) from one NP to another, emphasizing the particular interest of this methodology in providing a simple quantification method for the quality control of nanomedicines.
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Zdanovskaia, M. A., Martin-Drumel, M. - A., Kisiel, Z., Pirali, O., Esselman, B. J., Woods, R. C., & McMahon, R. J. (2022). The eight lowest-energy vibrational states of benzonitrile: analysis of Coriolis and Darling-Dennison couplings by millimeter-wave and far-infrared spectroscopy. Journal of Molecular Spectroscopy, 383, 111568.
Résumé: A combination of millimeter-wave and high-resolution infrared data is used to analyze the eight lowest-energy vibrational states of benzonitrile (C6H5CN, C2v, μa = 4.5 D), a benzene derivative recently detected in the interstellar medium. The overtone states v22 = 2 and v33 = 2, combination state v22 = 1, v33 = 1, and fundamental states v21 = 1 and v15 = 1 are studied for the first time by rotationally resolved spectroscopy. The three former states form a Coriolis- and Darling-Dennison-coupled triad of interacting states for which the coupling terms and highly precise, deperturbed energy separations have been measured. The use of sub-millimeter and far-infrared data together enabled the determination of the purely rotational and coupling parameters for the six lowest-energy vibrationally excited states of benzonitrile, along with their highly precise energies (E22 = 141.4810252 (57) cm−1, E33 = 160.5891953 (47) cm−1, E2×22 = 282.6295417 (83) cm−1, E22+33 = 302.5795909 (87) cm−1, E2×33 = 321.4923856 (77) cm−1, E21 = 372.257993 (10) cm−1). These energies, the resultant experimental anharmonicity constants (x22,22 = − 0.1663 cm−1, x33,33 = 0.1570 cm−1, and x22,33 = 0.4909 cm−1), and semi-experimental harmonic frequencies (ω22 = 142.9 cm−1 and ω33 = 161.0 cm−1) for the ν22 and ν33 states are compared to CCSD(T)/ANO1 predicted values. The spectroscopic and coupling constants determined in this work for the vibrational ground state, the two lowest-energy fundamental states, and the corresponding first overtone and combination states successfully predict experimental frequencies down to 8 GHz. Particularly for the vibrationally excited states, the ability to predict transition frequencies so far outside the frequency region in which the constants were determined confirms that the rotational and distortion constants, as well as the coupling terms, are determined reasonably close to their true values. The ability to accurately extrapolate also demonstrates the suitability of the determined constants as the basis for extraterrestrial identification and examination of these vibrational states of benzonitrile.
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