Journal of Molecular Spectroscopy最新文献

{"title":"XIAM-NQ: Implementation of exact quadrupole coupling","authors":"Sven Herbers","doi":"10.1016/j.jms.2024.111950","DOIUrl":"10.1016/j.jms.2024.111950","url":null,"abstract":"<div><div>In rotational spectroscopy, the nuclear quadrupole coupling of spins to the rotation of a molecule frequently leads to significant hyperfine splittings of spectral lines, complicating spectral analysis. This complexity increases further when internal rotation fine splittings, particularly from methyl groups, are also present. The <em>XIAM</em> program, recognized in the community for its ability to address methyl internal rotation and handle nuclear quadrupole coupling for a single nucleus, while neglecting off-diagonal matrix elements in the quantum number <em>J</em>, has now been enhanced. The updated version, <em>XIAM-NQ</em>, includes the previously omitted matrix elements, enabling an exact treatment of quadrupole coupling. This new version offers precise spectral fits with minimal fitting times, even for molecules containing bromine and iodine nuclei. The effectiveness of <em>XIAM-NQ</em> is demonstrated on <em>o-</em>halotoluenes and <em>m-</em>chlorotoluene.</div></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"405 ","pages":"Article 111950"},"PeriodicalIF":1.4,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426407","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":"Geometry of the argon…imidazole complex revealed by the microwave spectra of four isotopologues","authors":"Ryan Welch ,&nbsp;Mark D. Marshall ,&nbsp;Eva Gougoula ,&nbsp;Nicholas R. Walker ,&nbsp;Helen O. Leung","doi":"10.1016/j.jms.2024.111948","DOIUrl":"10.1016/j.jms.2024.111948","url":null,"abstract":"<div><div>The rotational spectra of four isotopologues of an isolated complex formed between an argon atom and imidazole, Ar…imidazole, have been recorded in the 6–19 GHz region by Fourier transform microwave spectroscopy. Rotational transition frequencies have been fitted to Watson’s <em>S</em>-reduced Hamiltonian to yield rotational, centrifugal distortion and nuclear quadrupole coupling constants for the complex. Rotational constants determined for the parent and three ¹⁵N-containing isotopologues allow the three-dimensional structure of the complex to be described. The two angles, θ and ϕ, which define the orientation of the Ar atom relative to the imidazole ring have been determined for the first time in addition to the distance between Ar and the center of mass of the imidazole sub-unit, <em>R</em>. Fitting of structural parameters to the experimentally-determined moments of inertia yields a structure where Ar is positioned above the ring plane at a distance of 3.519 Å from the center of mass of the imidazole sub-unit. In the experimentally determined, average geometry, the intermolecular axis (drawn through Ar and the center of mass of the imidazole sub-unit) is oriented at 6° from the normal to the ring plane. The experimental results allow for four alternative possibilities for ϕ with 62.0(39)° being that which is most consistent with expectations for this parameter based on previous work. The experimentally-determined nuclear quadrupole coupling constants imply that the electric field gradient at each of the nitrogen nuclei of imidazole does not significantly change on formation of the complex with Ar.</div></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"405 ","pages":"Article 111948"},"PeriodicalIF":1.4,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426405","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 molecular structure calculations for η4-butadiene ruthenium tricarbonyl","authors":"Adam M. Daly ,&nbsp;Kristen K. Roehling ,&nbsp;Rhett P. Hill ,&nbsp;Myla G. Gonzalez ,&nbsp;Xin Kang ,&nbsp;Lisa McElwee-White ,&nbsp;Stephen G. Kukolich","doi":"10.1016/j.jms.2024.111949","DOIUrl":"10.1016/j.jms.2024.111949","url":null,"abstract":"<div><div>The microwave spectrum of η⁴-butadiene ruthenium tricarbonyl was measured in the 5–15 GHz frequency range using a Flygare-Balle type pulsed beam Fourier transform microwave (FTMW) spectrometer. The rotational constants for the ¹⁰²Ru isotopologue were determined to have the following values: A = 932.20099(42), B = 858.03248(47) and C = 831.35161(37) MHz. The centrifugal distortion constant d_J is 0.0862(29)kHz. 22 a-dipole and 4c-dipole transitions were measured. Extensive high-level G16 calculations were made using DFT and MP2 methods with various basis sets, some including core-potentials (ECP). The best structure was calculated with Gaussian 16 using B3LYP/def2-QZVPP, which includes a core potential (ECP). Extensive all-electron calculations were made based on the best ECP structure to predict ¹⁰¹Ru and ⁹⁹Ru quadrupole coupling strengths. Quadrupole hyperfine structure splittings were measured for both ¹⁰¹Ru and ⁹⁹Ru. The hyperfine structure splittings for the ¹⁰¹Ru nuclear quadrupole were measured, yielding the values of 1.5χ_aa = 98.12(17) MHz and 0.25(χ_bb-χ_cc)  = 36.059(30). Measured hyperfine structure splittings for ⁹⁹Ru quadrupole coupling yielded the values of 1.5χ_aa = 16.99(77) MHz and 0.25(χ_bb-χ_cc)  = 6.23(32). These values are in reasonable agreement with some of the all-electron calculations.</div></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"405 ","pages":"Article 111949"},"PeriodicalIF":1.4,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142327336","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":"MARVEL analysis of high-resolution rovibrational spectra of the 18O12C18O, 17O12C18O, and 18O13C18O isotopologues of carbon dioxide","authors":"Ala’a A.A. Azzam ,&nbsp;Sumaya A.A. Azzam ,&nbsp;Karam A.A. Aburumman ,&nbsp;Jonathan Tennyson ,&nbsp;Sergei N. Yurchenko ,&nbsp;Attila G. Császár ,&nbsp;Tibor Furtenbacher","doi":"10.1016/j.jms.2024.111947","DOIUrl":"10.1016/j.jms.2024.111947","url":null,"abstract":"<div><p>For three rare isotopologues of carbon dioxide, ¹⁸O¹²C¹⁸O (828, according to a well-established shorthand notation), ¹⁷O¹²C¹⁸O (728), and ¹⁸O¹³C¹⁸O (838), 3923, 4318, and 1058 empirical rovibrational energy levels, respectively, are determined, using the MARVEL (Measured Active Rotational–Vibrational Energy Levels) protocol and code. For the isotopologues 828/728/838, the analysis of their spectroscopic network is based on 11<!--> <!-->353(7665)/11<!--> <!-->313(7700)/2155(1595) measured(unique) transitions, belonging to 165/113/50 vibrational bands, respectively. The measured transitions collected from the literature span the regions 953–12<!--> <!-->570 cm⁻¹ (for 828), 628–8197 cm⁻¹ (for 728), and 600–7918 cm⁻¹ (for 838). The number of critically evaluated and recommended energy levels of this study are 3923, 4318, and 1058 for the 828, 728, and 838 isotopologues of CO₂, respectively. Comparison of the empirical rovibrational energy levels determined in this study with their counterparts in two published databases, CDSD-2019, Ames-2021 and HITRAN shows very good overall agreement.</p></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"405 ","pages":"Article 111947"},"PeriodicalIF":1.4,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0022285224000742/pdfft?md5=06a646f80d55bee3ebc0c9dafbfac541&pid=1-s2.0-S0022285224000742-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142274264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rotational spectra of ten new fluoroethylene/CO2 clusters, (C2H3F)x(CO2)y: Application of data-centered methods to the assignment of spectra in complex mixtures","authors":"Prashansa B. Kannangara ,&nbsp;Hannah L. Fino ,&nbsp;Channing T. West ,&nbsp;Brooks H. Pate ,&nbsp;Sean A. Peebles ,&nbsp;Rebecca A. Peebles","doi":"10.1016/j.jms.2024.111938","DOIUrl":"10.1016/j.jms.2024.111938","url":null,"abstract":"<div><p>Chirped-pulse Fourier-transform microwave (CP-FTMW) spectroscopy has been used to measure the spectra of ten previously unobserved fluoroethylene (FE)/CO₂ clusters, (FE)_x(CO₂)_y, with x from 1 to 4 and y from 0 to 4. Multiple spectra were recorded with varying concentrations of CO₂ in the sample, and at least 400,000 free induction decays averaged per data set. This allowed implementation of data-centered approaches, using intensity variation, to identify subsets of transitions belonging to the same cluster species or those of similar composition, simplifying the assignment process for the complex mixture of clusters present. All spectra were fitted to Watson <em>A</em>-reduction Hamiltonians, including quartic distortion constants, with very few species requiring higher order distortion constants for satisfactory fits to be obtained. Computational data at MP2/6-311++G(2d,2p) and <em>ω</em>B97X-D/6-31+G(d,p) levels suggested FE:CO₂ ratios and likely structural arrangements of each cluster based on comparisons with experimental rotational constants.</p></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"404 ","pages":"Article 111938"},"PeriodicalIF":1.4,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0022285224000651/pdfft?md5=2176ca31fb02fa6cd55c89dd81def90e&pid=1-s2.0-S0022285224000651-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142099086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rotational spectroscopy and structure of 1,1-dichloro-1-silacyclohex-2-ene","authors":"Alexander R. Davies ,&nbsp;Nicole T. Moon ,&nbsp;Amanda J. Duerden ,&nbsp;Thomas M.C. McFadden ,&nbsp;Gamil A. Guirgis ,&nbsp;Nathan A. Seifert ,&nbsp;G.S. Grubbs II","doi":"10.1016/j.jms.2024.111939","DOIUrl":"10.1016/j.jms.2024.111939","url":null,"abstract":"<div><p>The ground state rotational spectrum of 1,1-dichloro-1-silacyclohex-2-ene has been recorded using a chirped-pulse Fourier transform microwave (CP-FTMW) spectrometer. Several isotopologues in their natural abundances have been observed in the free-jet expansion, and their spectra assigned, making it possible to present a partial heavy-atom substitution structure. Furthermore, the high resolution of this technique allows the complicated hyperfine splitting pattern to be largely deconvoluted. As a result, the on-diagonal nuclear quadrupole coupling constants for the two chlorine atoms have been determined for all observed isotopologues. Additionally, <em>χ_bc</em> is determined for both chlorine atoms of the parent species. The quadrupole coupling tensors for the parent species have been diagonalised, noting some assumptions have been made pertaining to the off-diagonal nuclear quadrupole coupling constants in the principal axis system, to yield reasonable values of <em>χ_zz</em> and <em>η</em> which are then compared.</p></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"404 ","pages":"Article 111939"},"PeriodicalIF":1.4,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142129717","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":"Symmetry properties, tunneling splittings of some vibrational energy levels and torsional IR spectra of the trans – and cis – conformers of hydroquinone molecule","authors":"G. Pitsevich ,&nbsp;A. Malevich","doi":"10.1016/j.jms.2024.111937","DOIUrl":"10.1016/j.jms.2024.111937","url":null,"abstract":"<div><p>Torsional vibrational states of trans − and cis − conformers belonging to point symmetry groups C_2H and C_2V, respectively, of hydroquinone molecules are classified according to the irreducible representations of the molecular symmetry group D_2H(M). A correspondence has been established between the symmetry elements of the D_2H(M) group and the symmetry elements on the torsional coordinate plane for two-dimensional surfaces of potential energy, wave functions, kinetic coefficients and dipole moment projections. A correspondence has been established between the symmetry species of the point symmetry groups C_2H, C_2V and the symmetry species of the molecular symmetry group D_2H(M). Conformational states, barriers to internal rotation and the above-mentioned characteristics of the hydroquinone molecule were calculated at the MP2/Aug-cc-pVDZ, MP2/Aug-cc-pVQZ, MP2/Aug-cc-pVTZ, MP2/CBS(aD,aT,aQ), and CCSD(T)/dAug-cc-pVDZ levels of theory. The calculated data sets were approximated using symmetry-adapted sets of basis functions. Using a numerical solution of the vibrational Schrödinger equation of restricted dimensionality, the energies and wave functions of 50 stationary torsional states of the hydroquinone molecule were determined for the first time. The values of tunneling splittings of the ground vibrational and a number of excited torsional states of trans − and cis − conformers were determined. In particular, when calculating at the MP2/CBS(aD,aT,aQ) level of theory, the values of tunneling splittings of the ground vibrational states of trans − and cis − conformers turned were 1.32*10^-6 and 1.62*10^-6 cm⁻¹, which is consistent with the experimentally established upper limit for this value in the cis − conformer by authors of [W. Caminati, S. Melandri, L. B. Favero, J.Chem.Phys., 100 (1994) 8569 – 8572] (0.2 MHz or 6.67*10^-6 cm⁻¹). The calculations of the matrix elements of the dipole moment operator and the partition function made it possible to simulate the torsional IR spectra of the molecule’s conformers at different temperatures. The frequencies of fundamental torsional vibrations in the trans – (267.1 and 269.0 cm⁻¹) and cis – (269.5 and 270.9 cm⁻¹) conformers, calculated at the MP2/CBS(aD,aT,aQ) level of theory, are in good agreement with the experimental value of frequency of this vibration (266 cm⁻¹), established in [W.G. Fateley, G.L. Carlson, F.F. Bentley, J.Phys.Chem., 79 (1975) 199–204.].</p></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"404 ","pages":"Article 111937"},"PeriodicalIF":1.4,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142002451","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":"Molecular structure analysis of xanthine alkaloids using terahertz spectroscopy","authors":"Ningyi Wang,&nbsp;Xinghao Huang,&nbsp;Jiamin Zhang,&nbsp;Xu Wu,&nbsp;Yan Peng,&nbsp;Yiming Zhu","doi":"10.1016/j.jms.2024.111936","DOIUrl":"10.1016/j.jms.2024.111936","url":null,"abstract":"<div><p>Caffeine, theophylline and theobromine are representative xanthine alkaloids, commonly used as stimulants due to their effects on the central nervous system. Despite their similar molecular structures, they have different pharmacological effects, necessitating a rapid and accurate identification method. In this study, terahertz time-domain spectroscopy (THz-TDS) was used to measure the absorption spectra of these three xanthine alkaloids within the range of 2.0–17.0 THz. The characteristic absorption peaks were visualized and analyzed basing on the quantum chemical calculations using Hartree-Fock (HF), Møller–Plesset perturbation theory (MP2) and density functional theory (DFT). Caffeine exhibited unique absorption peaks at 4.24, 5.00, and 11.13 THz. Theophylline showed characteristic peaks at 9.25, 12.20, and 15.09 THz. While theobromine exhibited characteristic peaks at 4.45, 7.68, and 11.21 THz. The results demonstrate that combining THz-TDS with DFT calculation can non-destructively, efficiently, and accurately identify these xanthine alkaloids, and providing valuable information for further understanding their pharmacological functions.</p></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"404 ","pages":"Article 111936"},"PeriodicalIF":1.4,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142012208","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":"Theoretical investigation of the electronic structure of the Rhodium Halides molecules RhF and RhCl with dipole moment calculation","authors":"Saleh N. Abdul Al,&nbsp;Diana Kaeen,&nbsp;Tarek H. Harb","doi":"10.1016/j.jms.2024.111929","DOIUrl":"10.1016/j.jms.2024.111929","url":null,"abstract":"<div><p>The current study involves an <em>ab</em> initio exploration of the ground and low-lying excited electronic states of the rhodium halide molecules RhF and RhCl using the complete active space self-consistent field (CASSCF) with multireference configuration interaction (MRCI+Q) method including single and double excitations and with Davidson corrections. We investigated the potential energy curves, the transition and permanent electric dipole moments, the electronic energy relative to the ground state <em>T_e</em>, the harmonic frequency <em>ω_e</em>, the internuclear distance <em>R_e</em>, and the rotational constant <em>B_e</em> corresponding to each of the bounded states. Our findings demonstrate good agreement with the available experimental data. Notably, this work represents the inaugural theoretical investigation of the excited states of RhF and RhCl molecules, identifying the ground state of both to be X³Π, as observed in the sole two experimental investigations.</p></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"404 ","pages":"Article 111929"},"PeriodicalIF":1.4,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141777157","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":"westerfit: A new program for spin–torsion–rotation spectra","authors":"J.H. Westerfield ,&nbsp;S.E. Worthington-Kirsch","doi":"10.1016/j.jms.2024.111928","DOIUrl":"10.1016/j.jms.2024.111928","url":null,"abstract":"<div><p>A new program, <span>westerfit</span>, has been developed to treat <span><math><msub><mrow><mi>C</mi></mrow><mrow><mi>s</mi></mrow></msub></math></span> molecules with internal rotation and spin angular momentum. It implements a single diagonalization Rho Axis Method approach for the torsion–rotation alongside a complete treatment of nuclear quadrupole interaction and spin–rotation coupling. Unlike other programs designed for internal rotation with spin effects, <span>westerfit</span> includes matrix elements off-diagonal in the rotational angular momentum quantum number, <span><math><mi>N</mi></math></span>, rather than the perturbative treatment of the spin–rotation and quadrupole interactions. This full combined approach allows fitting of all symmetrically allowed terms in both the spin–rotation and the quadrupole tensors as well as inclusion of higher order terms coupling the large amplitude motion to the spin angular momentum. The program was benchmarked against other published programs to test molecular cases of torsion–rotation, spin–rotation, and spin–torsion-rotation. All three tests produced a lower RMS. <span>westerfit</span> paves a way forward for complete treatment of spin–torsion–rotation problems regardless of barrier height or quadrupole moment.</p></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"404 ","pages":"Article 111928"},"PeriodicalIF":1.4,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141850717","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}