Journal of Molecular Spectroscopy最新文献

{"title":"Accurate equilibrium structures of some challenging molecules: FNO, ClNO, HONO, FNO2, and N2O","authors":"Jean Demaison ,&nbsp;Jacques Liévin ,&nbsp;Natalja Vogt","doi":"10.1016/j.jms.2023.111788","DOIUrl":"10.1016/j.jms.2023.111788","url":null,"abstract":"<div><p>It is sometimes difficult to determine the structure of some molecules because the optimization using standard <em>ab initio</em> methods (coupled-cluster with single, double, and perturbative triples [CCSD(T)] level) does not give the correct result and the experimental and semiexperimental methods are not accurate because the system of normal equations of the least-squares method is ill-conditioned. In such a case, it may be still possible to derive an accurate equilibrium structure in the following way: the experimental rotational constants are compared to those obtained at the CCSD(T) level, the latter being corrected to take into account the rovibrational correction (and, if necessary, the electronic correction). Extrapolating (or interpolating) the rotational constants calculated with different basis sets (e.g. cc-pwCVTZ and cc-pwCVQZ) towards the experimental values as a function of the bond lengths and angles permits to obtain an accurate equilibrium structure. This method is first tested on two molecules for which the multireference effects are important: O₃ and HOON. It is then, applied to molecules with a weak N–X bond (HONO, FNO, ClNO, FNO₂, and N₂O) for which the single reference CCSD(T) method gives bonds that are too short. The results are compared to the experimental and semiexperimental equilibrium structures. As a further check, the structure of ClNO is calculated at the CCSDTQ level and the structures of FNO and ClNO are calculated at the MRCI-F12 level. From a comparison of the different results, it appears that the accuracy of the proposed method is better than 0.002 Å for the bond lengths and 0.3° for the angles.</p></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48144031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rotational spectroscopy of oxirane-2,2-d2, c-CD2CH2O, and its tentative detection toward IRAS 16293-2422 B","authors":"Holger S.P. Müller ,&nbsp;Jes K. Jørgensen ,&nbsp;Jean-Claude Guillemin ,&nbsp;Frank Lewen ,&nbsp;Stephan Schlemmer","doi":"10.1016/j.jms.2023.111777","DOIUrl":"https://doi.org/10.1016/j.jms.2023.111777","url":null,"abstract":"<div><p><span>We prepared a sample of oxirane<span> doubly deuterated at one C atom and studied its rotational spectrum in the laboratory for the first time between 120 GHz and 1094 GHz. Accurate spectroscopic parameters up to eighth order were determined, and the calculated rest frequencies were used to identify </span></span><span><math><mi>c</mi></math></span>-CD<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>CH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span><span>O tentatively in the interstellar medium in the Atacama Large Millimeter/submillimeter Array Protostellar Interferometric Line Survey (PILS) of the Class 0 protostellar system IRAS 16293-2422. The </span><span><math><mi>c</mi></math></span>-CD<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>CH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O to <span><math><mi>c</mi></math></span>-C<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>H<span><math><msub><mrow></mrow><mrow><mn>4</mn></mrow></msub></math></span>O ratio was estimated to be <span><math><mo>∼</mo></math></span>0.054 with <span><math><mrow><msub><mrow><mi>T</mi></mrow><mrow><mi>rot</mi></mrow></msub><mo>=</mo><mn>125</mn></mrow></math></span> K. This value translates to a D-to-H ratio of <span><math><mo>∼</mo></math></span>0.16 per H atom which is higher by a factor of 4.5 than the <span><math><mo>∼</mo></math></span>0.036 per H atom obtained for <span><math><mi>c</mi></math></span>-C<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>H<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>DO. Such increase in the degree of deuteration referenced to one H atom in multiply deuterated isotopologs compared to their singly deuterated variants have been observed commonly in recent years.</p></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49748197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Millimeter wave spectroscopy of propynal isotopologues and structure determination","authors":"Evan G. Robertson ,&nbsp;Mahmut Ruzi ,&nbsp;Don McNaughton ,&nbsp;Laurent Margulès ,&nbsp;Roman A. Motiyenko ,&nbsp;Jean-Claude Guillemin","doi":"10.1016/j.jms.2023.111786","DOIUrl":"10.1016/j.jms.2023.111786","url":null,"abstract":"<div><p>Rotational transitions of propynal (HCCCHO) have been measured in the 150–900 GHz region by millimeter wave spectroscopy and in the far infrared region by high resolution FTIR spectroscopy using a synchrotron source. For the parent isotopologue, assignment of MMW transitions up to very high quantum numbers (<em>J</em> = 100, <em>K</em>_a = 25) reveals evidence of extensive perturbations in the ground vibrational state due to Fermi-asymmetry resonance with an excited vibrational state. A fit to nearly 3000 ground state transitions yields effective constants that are suitable for describing relatively unperturbed rotational levels up to <em>K</em>_a = 13. Over 1000 transitions were assigned and fitted for each singly substituted ¹³C species and nearly 400 transitions for the ¹⁸O variant. Re-analysis of literature data on deuterated species, aided by centrifugal distortion constants from hybrid density functional theory calculations at the B2PLYP/aug-cc-pVTZ level, provides a further set of rotational constants. This allows determination of a <em>R</em>_m⁽²⁾ structure for propynal with the following geometry: r(C≡C) = 1.2066(15), r(C<img>C) = 1.4486(14), r(CO) = 1.2087(10), r(C­H ald) = 1.1069(8), r(C­H<!--> <!-->acet) = 1.0578(13), θ(CCC) = 176.71(22), θ(OCC) = 123.23(7), θ(HCC<!--> <!-->ald) = 114.43(31), θ(HCC<!--> <!-->acet) = 178.45(16). A new <em>R</em>_s structure was also derived.</p></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44838650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microwave spectrum and substitution structure of syn thiobenzoic acid","authors":"Aaron J. Reynolds,&nbsp;Kenneth R. Leopold","doi":"10.1016/j.jms.2023.111787","DOIUrl":"10.1016/j.jms.2023.111787","url":null,"abstract":"<div><p>The rotational spectrum of the <em>syn</em> conformer of thiobenzoic acid (C₆H₅COSH) has been observed by Fourier transform microwave spectroscopy in a supersonic jet. Spectra of all singly-substituted isotopologues involving ¹³C, as well as the ¹⁸O, ³³S, ³⁴S, and −SD derivatives have also been recorded. The isotopic data have been used to derive structural parameters of the molecular frame. The results are compared with density functional theory calculations at theM06-2X/6-311++G(d,p) level and show excellent agreement. The molecule is planar at the equilibrium geometry, and calculations of the energy profile for out-of-plane torsion of the SH group are presented. The <em>anti</em> conformer was not observed, consistent with calculations which indicate that it lies 2.6 kcal/mol higher in energy than the <em>syn</em> form.</p></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46010765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rotational spectroscopic studies of para-nitrobenzoic acid, para-aminobenzoic acid, para-chlorobenzoic acid, and para-hydroxybenzoic acid","authors":"Mohamad H. Al-Jabiri ,&nbsp;Arsh S. Hazrah ,&nbsp;Aran Insausti ,&nbsp;Yunjie Xu ,&nbsp;Wolfgang Jӓger","doi":"10.1016/j.jms.2023.111790","DOIUrl":"10.1016/j.jms.2023.111790","url":null,"abstract":"<div><p>The rotational spectra of four substituted benzoic acids, i.e., <em>para</em>-aminobenzoic acid, <em>para</em>-nitrobenzoic acid, <em>para</em>-chlorobenzoic acid, and <em>para</em>-hydroxybenzoic acid were recorded with a chirp-pulse Fourier transform microwave spectrometer and analysed in terms of rotational constants and, where applicable, nuclear quadrupole coupling constants and tunnelling motions. In all instances, the experimentally identified conformer contains a carboxylic acid group in the <em>cis</em>-arrangement. In the case of <em>para</em>-hydroxybenzoic acid, spectra of two conformers were observed which differ in the orientation of the <em>para</em>-OH group. Quantum chemical calculations at the B3LYP-D3BJ/def2-TZVP and B2PLYP-D3BJ/cc-pCVTZ levels show that the <em>trans</em>-conformers are about 23 kJ mol⁻¹ higher in energy than the global minimum <em>cis</em>-conformers. In general, the calculated rotational constants are in good agreement with the experimental derived ones. Agreement between calculated and experimental ¹⁴N and ^35/37Cl nuclear quadrupole coupling constants is somewhat worse and necessitated the use of the B2PLYP functional in the case of <em>para</em>-nitrobenzoic acid to reduce the discrepancy. Conversion barriers between possible conformers were calculated to explain the absence of tunnelling splittings and/or higher energy conformers in the experimental spectra. An analysis of the electron density distribution was used to rationalize the calculated out-of-plane excursions of the carboxylic acid group in the <em>trans</em>-conformers.</p></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42560575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spectroscopic study of the F1Σg+ outer well state in H2, HD and D2","authors":"K.-F. Lai,&nbsp;M. Beyer,&nbsp;W. Ubachs","doi":"10.1016/j.jms.2023.111778","DOIUrl":"https://doi.org/10.1016/j.jms.2023.111778","url":null,"abstract":"<div><p>Two-photon UV-photolysis of hydrogen sulfide molecules is applied to produce hydrogen molecules in highly excited vibrational levels in the X<span><math><mrow><msup><mrow></mrow><mrow><mn>1</mn></mrow></msup><msubsup><mrow><mi>Σ</mi></mrow><mrow><mi>g</mi></mrow><mrow><mo>+</mo></mrow></msubsup></mrow></math></span> electronic ground state, up to the dissociation energy and into the quasibound region. Photolysis precursors H₂S, HDS and D₂S are used to produce vibrationally hot H₂, HD and D₂. The wave function density at large internuclear separation is excited via two-photon transitions in the F<span><math><mrow><msup><mrow></mrow><mrow><mn>1</mn></mrow></msup><msubsup><mrow><mi>Σ</mi></mrow><mrow><mi>g</mi></mrow><mrow><mo>+</mo></mrow></msubsup></mrow></math></span> - X<span><math><mrow><msup><mrow></mrow><mrow><mn>1</mn></mrow></msup><msubsup><mrow><mi>Σ</mi></mrow><mrow><mi>g</mi></mrow><mrow><mo>+</mo></mrow></msubsup></mrow></math></span> system to probe ro-vibrational levels in the first F<span><math><mrow><msup><mrow></mrow><mrow><mn>1</mn></mrow></msup><msubsup><mrow><mi>Σ</mi></mrow><mrow><mi>g</mi></mrow><mrow><mo>+</mo></mrow></msubsup></mrow></math></span> outer well state of <em>gerade</em> symmetry. Combining with accurate knowledge of the X<span><math><mrow><msup><mrow></mrow><mrow><mn>1</mn></mrow></msup><msubsup><mrow><mi>Σ</mi></mrow><mrow><mi>g</mi></mrow><mrow><mo>+</mo></mrow></msubsup></mrow></math></span> (<span><math><mrow><mi>v</mi><mo>,</mo><mi>J</mi></mrow></math></span>) levels from advanced ab initio calculations, energies of rovibrational levels in the F<span><math><mrow><msup><mrow></mrow><mrow><mn>1</mn></mrow></msup><msubsup><mrow><mi>Σ</mi></mrow><mrow><mi>g</mi></mrow><mrow><mo>+</mo></mrow></msubsup></mrow></math></span> state are determined. For the H₂ isotopologue a three-laser scheme is employed yielding level energies at accuracies of <span><math><mrow><mn>4</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup></mrow></math></span> cm⁻¹ for F(<span><math><mrow><mi>v</mi><mo>=</mo><mn>0</mn><mo>,</mo><mi>J</mi></mrow></math></span>) up to <span><math><mrow><mi>J</mi><mo>=</mo><mn>21</mn></mrow></math></span> and for some low <span><math><mi>J</mi></math></span> values of F(<span><math><mrow><mi>v</mi><mo>=</mo><mn>1</mn></mrow></math></span>). A two-laser scheme was applied to determine level energies in H₂ for F(<span><math><mrow><mi>v</mi><mo>=</mo><mn>0</mn><mo>−</mo><mn>4</mn></mrow></math></span>) levels as well as for various F levels in HD and D₂, also up to large rotational quantum numbers. The latter measurements in the two-laser scheme are performed at lower resolution and the accuracy is strongly limited to 0.5 cm⁻¹ by ac-Stark effects. For H₂ a new quasibound resonance X<span><math><mrow><msup><mrow></mrow><mrow><mn>1</mn></mrow></msup><msu","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49758627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A local Gaussian Processes method for fitting potential surfaces that obviates the need to invert large matrices","authors":"Nuoyan Yang ,&nbsp;Spencer Hill ,&nbsp;Sergei Manzhos ,&nbsp;Tucker Carrington","doi":"10.1016/j.jms.2023.111774","DOIUrl":"10.1016/j.jms.2023.111774","url":null,"abstract":"<div><p><span>In order to compute a vibrational spectrum, one often wishes to start with a set of ab initio Born–Oppenheimer potential values at points, called fitting points, and interpolate or fit to find values of the potential at quadrature or collocation points. It is common to do this </span><span><math><mrow><mi>o</mi><mi>n</mi><mi>c</mi><mi>e</mi></mrow></math></span><span> to build a potential energy surface (PES). Once the PES is known, it can be evaluated at any point in configuration space. Gaussian Process (GP) is frequently being used to make a PES. As is the case in other interpolation methods, to use GP one must store and invert a matrix whose size is the number of fitting points. The matrix is sometimes large enough that approximations are introduced to reduce the cost of the calculation. We show that is possible to use many local Gaussian Process fits rather than one global fit. Retaining only local Gaussians and the associated points works well despite the fact that other Gaussians have tails with significant amplitude in the local region. We demonstrate that from the potential values obtained from the local fits it is possible to compute accurate energy levels of formaldehyde. In one calculation, potential values were obtained with </span><span><math><mrow><mi>N</mi><mo>=</mo><mn>120</mn><mo>,</mo><mn>000</mn></mrow></math></span> fitting points by inverting matrices of size less than <span><math><mrow><mi>m</mi><mo>=</mo><mn>400</mn></mrow></math></span>. The local idea reduces the cost from <span><math><msup><mrow><mi>N</mi></mrow><mrow><mn>3</mn></mrow></msup></math></span> to <span><math><mrow><mi>T</mi><mrow><mo>(</mo><msup><mrow><mi>m</mi></mrow><mrow><mn>3</mn></mrow></msup><mo>+</mo><mi>N</mi><mo>)</mo></mrow></mrow></math></span>, where <span><math><mi>T</mi></math></span> is the number of desired potential points.</p></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47973820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A study of the local to normal mode transition in pyramidal molecules and their vibrational description in terms of an algebraic model","authors":"O. Guzmán-Juárez,&nbsp;E. Suárez,&nbsp;R. Lemus","doi":"10.1016/j.jms.2023.111775","DOIUrl":"10.1016/j.jms.2023.111775","url":null,"abstract":"<div><p><span>First a new perspective to study the local to normal mode transition in the series of pyramidal molecules is presented. Then a full study of the vibrational excitations of the series of pyramidal molecules XH</span><span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span><span> with X = P, As and Sb is given in the framework of a polyad-conserving Hamiltonian of a set of interacting Morse oscillators. The model is based on an algebraic representation of the Hamiltonian in terms of </span><span><math><mrow><mi>s</mi><mi>u</mi><mrow><mo>(</mo><mn>2</mn><mo>)</mo></mrow></mrow></math></span>-operators. A simple Hamiltonian including both Fermi and Darling–Dennison interactions is considered. For the PH<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span> molecule a fit involving 64 experimental energies up to polyad 8 (energies up to 9054 cm⁻¹) provided an <span><math><mrow><mi>rms</mi><mo>=</mo><mn>1</mn><mo>.</mo><mn>74</mn><mspace></mspace><msup><mrow><mi>cm</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span> using a Hamiltonian with <span><math><mrow><mn>14</mn><mo>+</mo><mn>3</mn></mrow></math></span>(frozen) parameters. For the AsH<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>, with 35 experimental energies the deviation obtained was <span><math><mrow><mi>rms</mi><mo>=</mo><mn>2</mn><mo>.</mo><mn>50</mn><mspace></mspace><msup><mrow><mi>cm</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span> with <span><math><mrow><mn>10</mn><mo>+</mo><mn>4</mn></mrow></math></span> parameters. Lastly, for the SbH<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span> molecule, considering 23 experimental energy levels an <span><math><mrow><mi>rms</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>86</mn><mspace></mspace><msup><mrow><mi>cm</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span> was reached with <span><math><mrow><mn>9</mn><mo>+</mo><mn>6</mn></mrow></math></span> parameters. In all cases the polyad scheme <span><math><mrow><mi>P</mi><mo>=</mo><mn>2</mn><mrow><mo>(</mo><msub><mrow><mi>ν</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>+</mo><msub><mrow><mi>ν</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>)</mo></mrow><mo>+</mo><msub><mrow><mi>ν</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>+</mo><msub><mrow><mi>ν</mi></mrow><mrow><mn>4</mn></mrow></msub></mrow></math></span> was considered.</p></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46111024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gas phase electronic spectra of xylene-water aggregates","authors":"Jack E. Fulker ,&nbsp;Alejandro Gutiérrez-Quintanilla ,&nbsp;Wendy A. Brown ,&nbsp;Gustavo A. Pino ,&nbsp;Antoine Hacquard ,&nbsp;Ana Niedojadlo ,&nbsp;Jennifer A. Noble","doi":"10.1016/j.jms.2023.111761","DOIUrl":"10.1016/j.jms.2023.111761","url":null,"abstract":"<div><p>Using a jet spectroscopy molecular beam setup, gas phase electronic spectra of three xylene isomers (<em>para</em>, <em>meta</em> and <em>ortho</em>) have been collected for the neutral monomer species as well as for their clusters with one and two water molecules. Scans at a resolution of ±0.02 nm showed a clear 0–0 transition for each xylene isomer as well as the vibronic progression. The spectra were assigned with the help of Franck–Condon factor PGOPHER simulations from theoretical studies at the CAM-B3LYP/aug-cc-pVDZ level of theory. The vibronic spectra of the xylene<span><math><mi>⋅</mi></math></span>H<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O and xylene<span><math><mi>⋅</mi></math></span>(H₂O)₂ clusters showed broad features between 36800–38400 cm⁻¹ (260–272 nm) for <em>p</em>- and <em>m</em>-xylene, while the water clusters of <em>o</em>-xylene gave more defined bands. The separation of the vibronic bands in the clusters mirrors the progression of the neutral monomers implying that, for the S₁ <span><math><mo>←</mo></math></span> S₀ transition, it is the same vibrational modes that are involved in the monomer as in the clusters with water. Both the separation and the spectral width of the bands can be explained by the calculated differences in geometries of the clusters in the ground and first electronic excited states.</p></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42386053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Infrared spectra of gaseous peroxychloroformyl radical ClC(O)OO: A key intermediate in the conversion of CO to CO2 in the Venus atmosphere","authors":"Bedabyas Behera ,&nbsp;Yuan-Pern Lee","doi":"10.1016/j.jms.2023.111771","DOIUrl":"10.1016/j.jms.2023.111771","url":null,"abstract":"<div><p>The peroxychloroformyl radical, ClC(O)OO, was proposed to play a critical role in the catalytic conversion of CO to CO₂ in the atmosphere of Venus, but direct spectral characterization of this species in the gaseous phase is lacking. Photolysis of a mixture of (ClCO)₂ and O₂ near 50 Torr with laser light at 248 nm produced absorption bands of CO, CO₂, Cl₂CO, and transient absorption bands that can be assigned to ClCO, <em>trans</em>-ClC(O)OO, and <em>cis</em>-ClC(O)OO. Bands at 937, 1014, and 1902 cm⁻¹ are assigned to the OCO bending (ν₃), overtone of C−Cl stretching (2ν₅), and C=O stretching (ν₁) modes of <em>trans-</em>ClC(O)OO. According to rotational contour simulations with PGOPHER, two bands ∼ 1883 and ∼ 1928 cm⁻¹ also contribute to the band near 1902 cm⁻¹; they might be assigned to the ν₂ + ν₈ + ν₉ mode of <em>cis</em>-ClC(O)OO and the ν₂ + ν₄ mode of <em>trans-</em>ClC(O)OO, whereas the band near 937 cm⁻¹ might have contribution from the 2ν₆ (overtone of OC=O bending) mode of <em>cis</em>-ClC(O)OO near 928 cm⁻¹. Bands at 964, 1110, and 1837 cm⁻¹ are assigned to the anti-phase C–O and O–O stretching (ν₃), O–O stretching (ν₂), and C=O stretching (ν₁) modes of <em>cis-</em>ClC(O)OO. The band near 1837 cm⁻¹ might have contribution from the 2ν₃ mode of <em>trans</em>-ClC(O)OO and <em>cis</em>-ClC(O)OO near 1829 and &lt; 1829 cm⁻¹, respectively. From the temporal evolution of CO and CO₂, we confirmed that the addition of O₂ to the photolyzed (ClCO)₂ system to form ClC(O)OO enhanced the formation of CO₂, supporting the proposed catalytic mechanism.</p></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49121431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}