Pub Date : 2025-07-09DOI: 10.1016/j.jms.2025.112031
Saurabh Mishra
Non-covalent interactions such as hydrogen bonding and π–π stacking are central to molecular architecture. This study investigates the indole dimer near the band origin at 35238 cm−1 using IR-UV double resonance spectroscopy and DFT calculations. The IDIR spectrum shows a red-shifted NH stretch at 3420 cm−1, indicative of hydrogen bonding. Computational analyses with B97D and B3LYP-D3 functionals favor N–H‧‧‧π bonded structures. Among these, we assign a tilted geometry featuring N–H‧‧‧π interaction as the most consistent with experimental observations. The broad spectral profile also suggests the coexistence of multiple low-energy isomers.
{"title":"Exploring indole dimer structures at the band origin: A spectroscopic gas phase IR analysis","authors":"Saurabh Mishra","doi":"10.1016/j.jms.2025.112031","DOIUrl":"10.1016/j.jms.2025.112031","url":null,"abstract":"<div><div>Non-covalent interactions such as hydrogen bonding and π–π stacking are central to molecular architecture. This study investigates the indole dimer near the band origin at 35238 cm<sup>−1</sup> using IR-UV double resonance spectroscopy and DFT calculations. The IDIR spectrum shows a red-shifted N<img>H stretch at 3420 cm<sup>−1</sup>, indicative of hydrogen bonding. Computational analyses with B97D and B3LYP-D3 functionals favor N–H‧‧‧π bonded structures. Among these, we assign a tilted geometry featuring N–H‧‧‧π interaction as the most consistent with experimental observations. The broad spectral profile also suggests the coexistence of multiple low-energy isomers.</div></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"411 ","pages":"Article 112031"},"PeriodicalIF":1.4,"publicationDate":"2025-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144611716","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}
Pub Date : 2025-06-01DOI: 10.1016/j.jms.2025.112022
Kristin N. Bales , Akhila Swarna , James J. O'Brien , Leah C. O'Brien
The (0,0) and (0,1) bands of the A1 – X0+ and B1 – X0+ transitions of tungsten monoxide (WO) have been recorded in high resolution using intracavity laser absorption spectroscopy techniques (ILS and ILS-FTS). Lines for all four abundant isotopologues, 182WO, 183WO, 184WO, and 186WO, are observed and have been rotationally analyzed and fit using a constrained-variables approach in PGOPHER. While these transitions have been previously described in the literature, this new analysis incorporates all four isotopologues and presents evidence for an avoided crossing interaction between the v = 0 vibrational levels of the A1 and B1 states. New values for spectroscopic constants that incorporate the perturbation interactions are presented and compared to literature results.
{"title":"Deperturbation analysis of an avoided crossing in the A1 v = 0 and B1 v = 0 states of WO","authors":"Kristin N. Bales , Akhila Swarna , James J. O'Brien , Leah C. O'Brien","doi":"10.1016/j.jms.2025.112022","DOIUrl":"10.1016/j.jms.2025.112022","url":null,"abstract":"<div><div>The (0,0) and (0,1) bands of the A1 – X0<sup>+</sup> and B1 – X0<sup>+</sup> transitions of tungsten monoxide (WO) have been recorded in high resolution using intracavity laser absorption spectroscopy techniques (ILS and ILS-FTS). Lines for all four abundant isotopologues, <sup>182</sup>WO, <sup>183</sup>WO, <sup>184</sup>WO, and <sup>186</sup>WO, are observed and have been rotationally analyzed and fit using a constrained-variables approach in PGOPHER. While these transitions have been previously described in the literature, this new analysis incorporates all four isotopologues and presents e<em>v</em>idence for an avoided crossing interaction between the v = 0 vibrational levels of the A1 and B1 states. New values for spectroscopic constants that incorporate the perturbation interactions are presented and compared to literature results.</div></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"410 ","pages":"Article 112022"},"PeriodicalIF":1.4,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144196135","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}
Pub Date : 2025-06-01DOI: 10.1016/j.jms.2025.112023
Termeh Bashiri , Phelan Yu , Nicholas R. Hutzler , Timothy C. Steimle , Carlos Abad , Mitchio Okumura
This study presents an experimental determination of spectroscopic parameters for the less-abundant isotopologues 42CaF and 44CaF, alongside 40CaF, by high resolution laser-induced fluorescence spectroscopy in a skimmed free jet expansion. We recorded spectra near the natural linewidth limit and derived spectroscopic constants for both and states, including the fine and 19F magnetic hyperfine parameters. We also estimated the r(44Ca/40Ca) isotope amount ratio, demonstrating the potential use of optical spectroscopy for isotope analysis.
{"title":"A molecular beam study of the (0,0)A2Π←X2Σ+ band of CaF isotopologues","authors":"Termeh Bashiri , Phelan Yu , Nicholas R. Hutzler , Timothy C. Steimle , Carlos Abad , Mitchio Okumura","doi":"10.1016/j.jms.2025.112023","DOIUrl":"10.1016/j.jms.2025.112023","url":null,"abstract":"<div><div>This study presents an experimental determination of spectroscopic parameters for the less-abundant isotopologues <sup>42</sup>CaF and <sup>44</sup>CaF, alongside <sup>40</sup>CaF, by high resolution laser-induced fluorescence spectroscopy in a skimmed free jet expansion. We recorded spectra near the natural linewidth limit and derived spectroscopic constants for both <span><math><mrow><msup><mrow><mi>X</mi></mrow><mrow><mn>2</mn></mrow></msup><msup><mrow><mi>Σ</mi></mrow><mrow><mo>+</mo></mrow></msup></mrow></math></span> and <span><math><mrow><msup><mrow><mi>A</mi></mrow><mrow><mn>2</mn></mrow></msup><mi>Π</mi></mrow></math></span> states, including the fine and <sup>19</sup>F magnetic hyperfine parameters. We also estimated the <em>r</em>(<sup>44</sup>Ca/<sup>40</sup>Ca) isotope amount ratio, demonstrating the potential use of optical spectroscopy for isotope analysis.</div></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"410 ","pages":"Article 112023"},"PeriodicalIF":1.4,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144470219","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}
Pub Date : 2025-05-16DOI: 10.1016/j.jms.2025.112021
K.A.E. Meyer, E. Garand
The impact of alkali metal ions (Li+, Na+, and K+) on the structure and vibrations in metal ion-diglycine complexes with up to two water molecules (M+GlyGly-nH2O) is examined using cryogenic infrared action spectroscopy, conformer-specific IR-IR spectroscopy, H2O/D2O isotopic substitution experiments, and scaled, harmonic DFT calculations. While the main conformer is identical for all metal ions for the bare complex (M+GlyGly), the conformers observed upon the addition of water are dependent on the nature of the metal ion and the impact of solvation is distinctly larger for the Li+ than for the K+ ion. The number of solvent molecules needed to change the initial peptide conformation differs between the metal ions and is smaller for Li+ than for the larger metal ions. The comparison of the spectra upon the sequential addition of water reveals how solvation impacts the electric field strength of the metal ions in these clusters. In all cases, the addition of water molecules reduces the strength of the interaction between the metal ion and the peptide and consequently, reduces the strength of the electric field induced in the peptide.
{"title":"Impact of the metal ion and microsolvation on the structure and vibrations in a small model peptide","authors":"K.A.E. Meyer, E. Garand","doi":"10.1016/j.jms.2025.112021","DOIUrl":"10.1016/j.jms.2025.112021","url":null,"abstract":"<div><div>The impact of alkali metal ions (Li<sup>+</sup>, Na<sup>+</sup>, and K<sup>+</sup>) on the structure and vibrations in metal ion-diglycine complexes with up to two water molecules (M<sup>+</sup>GlyGly-<em>n</em>H<sub>2</sub>O) is examined using cryogenic infrared action spectroscopy, conformer-specific IR-IR spectroscopy, H<sub>2</sub>O/D<sub>2</sub>O isotopic substitution experiments, and scaled, harmonic DFT calculations. While the main conformer is identical for all metal ions for the bare complex (M<sup>+</sup>GlyGly), the conformers observed upon the addition of water are dependent on the nature of the metal ion and the impact of solvation is distinctly larger for the Li<sup>+</sup> than for the K<sup>+</sup> ion. The number of solvent molecules needed to change the initial peptide conformation differs between the metal ions and is smaller for Li<sup>+</sup> than for the larger metal ions. The comparison of the spectra upon the sequential addition of water reveals how solvation impacts the electric field strength of the metal ions in these clusters. In all cases, the addition of water molecules reduces the strength of the interaction between the metal ion and the peptide and consequently, reduces the strength of the electric field induced in the peptide.</div></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"410 ","pages":"Article 112021"},"PeriodicalIF":1.4,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144168695","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}
Pub Date : 2025-04-11DOI: 10.1016/j.jms.2025.112011
Zhuozhao Li , Linqiao Guo , Lei Zhang , Kai Wang , Wenli Zou
Multi-reference configuration interaction calculations are carried out to elucidate the distribution of low-lying valence and Rydberg states of antimony monofluoride (SbF) below 50000 cm−1, where the effects of core–valence correlation and spin–orbit coupling have been employed. From the potential energy curves, the spectroscopic constants of seven (quasi-)bound -S and fourteen (quasi-)bound states have been derived, which agree well with the experimental values. Our results show that the second state involves the occupation on the Rydberg shell 6 of Sb, which settles the assignment of the so-called “” and “” states in the ultraviolet spectra of SbF. With the help of the more accurate coupled cluster calculations, the dissociation energy () of SbF is determined to be 4.24 eV at the theoretical limit, being 0.2 eV smaller than the widely used empirical value in the literature.
{"title":"Theoretical study on the low-lying electronic states of SbF","authors":"Zhuozhao Li , Linqiao Guo , Lei Zhang , Kai Wang , Wenli Zou","doi":"10.1016/j.jms.2025.112011","DOIUrl":"10.1016/j.jms.2025.112011","url":null,"abstract":"<div><div>Multi-reference configuration interaction calculations are carried out to elucidate the distribution of low-lying valence and Rydberg states of antimony monofluoride (SbF) below 50000 cm<sup>−1</sup>, where the effects of core–valence correlation and spin–orbit coupling have been employed. From the potential energy curves, the spectroscopic constants of seven (quasi-)bound <span><math><mi>Λ</mi></math></span>-S and fourteen (quasi-)bound <span><math><mi>Ω</mi></math></span> states have been derived, which agree well with the experimental values. Our results show that the second <span><math><mrow><msup><mrow></mrow><mrow><mn>3</mn></mrow></msup><mi>Π</mi></mrow></math></span> state involves the occupation on the Rydberg shell 6<span><math><mi>s</mi></math></span> of Sb, which settles the assignment of the so-called “<span><math><msub><mrow><mi>C</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>” and “<span><math><mrow><msub><mrow><mi>C</mi></mrow><mrow><mn>3</mn></mrow></msub><mn>1</mn></mrow></math></span>” states in the ultraviolet spectra of SbF. With the help of the more accurate coupled cluster calculations, the dissociation energy (<span><math><msub><mrow><mi>D</mi></mrow><mrow><mi>e</mi></mrow></msub></math></span>) of SbF is determined to be 4.24 eV at the theoretical limit, being 0.2 eV smaller than the widely used empirical value in the literature.</div></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"410 ","pages":"Article 112011"},"PeriodicalIF":1.4,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143830243","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}
Pub Date : 2025-03-01DOI: 10.1016/j.jms.2025.112010
Wafaa M. Fawzy
<div><div>We report the first accurate global fits for the rotation-spin-tunneling transitions in the microwave spectrum of the O<sub>2</sub>(<span><math><mmultiscripts><msubsup><mi>Σ</mi><mi>g</mi><mo>−</mo></msubsup><mprescripts></mprescripts><mspace></mspace><mn>3</mn></mmultiscripts></math></span>)-SO<sub>2</sub> (<sup>1</sup>A<sub>1</sub>) weakly bonded open-shell complex. In addition, we present a new ab initio investigation of the potential energy surface of O<sub>2</sub>(<span><math><mmultiscripts><msubsup><mi>Σ</mi><mi>g</mi><mo>−</mo></msubsup><mprescripts></mprescripts><mspace></mspace><mn>3</mn></mmultiscripts></math></span>)-SO<sub>2</sub>, using the UCCSD(T)/aug-cc-pV(n + d)Z level of theory where <em>n</em> = 2 and 3. Analysis of the spectrum identified a-type and c-type transitions, frequencies of the a-type were not shifted while those of the c-type were shifted due to tunneling of the O<sub>2</sub> and the SO<sub>2</sub> moieties in the dimer. Only the A<sub>1</sub> symmetric tunneling state was detected because the antisymmetric A<sub>2</sub> state is not allowed by nuclear spin statistics in O<sub>2</sub>-SO<sub>2</sub>. Least squares fits with a standard deviation of 1 kHz were obtained using two computer codes incorporating semi-rigid rotor Hamiltonians that employ two different angular momenta coupling schemes. Results of the fits determined the effective tunneling frequency in the A<sub>1</sub> symmetric state as <span><math><msub><mi>ν</mi><msub><mi>T</mi><mn>1</mn></msub></msub></math></span>= 2373.61134 <span><math><mo>±</mo></math></span>16 MHz, the electron spin coupling constant λ = 42,870.2186 <span><math><mo>±</mo></math></span>43 MHz, the rotational constants A = 7099.44 <span><math><mo>±</mo></math></span>33, B = 1528.886 <span><math><mo>±</mo></math></span>5, C = 1763.36 <span><math><mo>±</mo></math></span>6 MHz. The value of <span><math><msub><mi>ν</mi><msub><mi>T</mi><mn>1</mn></msub></msub></math></span> equals the tunneling splitting (<span><math><msub><mi>Δ</mi><msub><mi>T</mi><mn>1</mn></msub></msub></math></span>) between the<span><math><msubsup><mi>A</mi><mn>1</mn><mo>+</mo></msubsup></math></span> and <span><math><msubsup><mi>A</mi><mn>1</mn><mo>−</mo></msubsup></math></span> symmetric tunneling states in the dimer, where the<span><math><msubsup><mi>A</mi><mn>1</mn><mo>+</mo></msubsup></math></span> and <span><math><msubsup><mi>A</mi><mn>1</mn><mo>−</mo></msubsup></math></span> levels are shifted in energy by <span><math><mo>−</mo><mfrac><mn>1</mn><mn>2</mn></mfrac><msub><mi>ν</mi><msub><mi>T</mi><mn>1</mn></msub></msub></math></span> and <span><math><mo>+</mo><mfrac><mn>1</mn><mn>2</mn></mfrac><msub><mi>ν</mi><msub><mi>T</mi><mn>1</mn></msub></msub></math></span>, respectively. The ab initio study identified a global minimum energy structure of C<sub>1</sub> symmetry and a metastable local minimum of C<sub>s</sub> symmetry. We computed the optimized geometries of four equivalent configurations in the m
{"title":"New spectroscopic fits and ab initio study of the O2(Σg−3)-SO2 (1A1) open-shell dimer","authors":"Wafaa M. Fawzy","doi":"10.1016/j.jms.2025.112010","DOIUrl":"10.1016/j.jms.2025.112010","url":null,"abstract":"<div><div>We report the first accurate global fits for the rotation-spin-tunneling transitions in the microwave spectrum of the O<sub>2</sub>(<span><math><mmultiscripts><msubsup><mi>Σ</mi><mi>g</mi><mo>−</mo></msubsup><mprescripts></mprescripts><mspace></mspace><mn>3</mn></mmultiscripts></math></span>)-SO<sub>2</sub> (<sup>1</sup>A<sub>1</sub>) weakly bonded open-shell complex. In addition, we present a new ab initio investigation of the potential energy surface of O<sub>2</sub>(<span><math><mmultiscripts><msubsup><mi>Σ</mi><mi>g</mi><mo>−</mo></msubsup><mprescripts></mprescripts><mspace></mspace><mn>3</mn></mmultiscripts></math></span>)-SO<sub>2</sub>, using the UCCSD(T)/aug-cc-pV(n + d)Z level of theory where <em>n</em> = 2 and 3. Analysis of the spectrum identified a-type and c-type transitions, frequencies of the a-type were not shifted while those of the c-type were shifted due to tunneling of the O<sub>2</sub> and the SO<sub>2</sub> moieties in the dimer. Only the A<sub>1</sub> symmetric tunneling state was detected because the antisymmetric A<sub>2</sub> state is not allowed by nuclear spin statistics in O<sub>2</sub>-SO<sub>2</sub>. Least squares fits with a standard deviation of 1 kHz were obtained using two computer codes incorporating semi-rigid rotor Hamiltonians that employ two different angular momenta coupling schemes. Results of the fits determined the effective tunneling frequency in the A<sub>1</sub> symmetric state as <span><math><msub><mi>ν</mi><msub><mi>T</mi><mn>1</mn></msub></msub></math></span>= 2373.61134 <span><math><mo>±</mo></math></span>16 MHz, the electron spin coupling constant λ = 42,870.2186 <span><math><mo>±</mo></math></span>43 MHz, the rotational constants A = 7099.44 <span><math><mo>±</mo></math></span>33, B = 1528.886 <span><math><mo>±</mo></math></span>5, C = 1763.36 <span><math><mo>±</mo></math></span>6 MHz. The value of <span><math><msub><mi>ν</mi><msub><mi>T</mi><mn>1</mn></msub></msub></math></span> equals the tunneling splitting (<span><math><msub><mi>Δ</mi><msub><mi>T</mi><mn>1</mn></msub></msub></math></span>) between the<span><math><msubsup><mi>A</mi><mn>1</mn><mo>+</mo></msubsup></math></span> and <span><math><msubsup><mi>A</mi><mn>1</mn><mo>−</mo></msubsup></math></span> symmetric tunneling states in the dimer, where the<span><math><msubsup><mi>A</mi><mn>1</mn><mo>+</mo></msubsup></math></span> and <span><math><msubsup><mi>A</mi><mn>1</mn><mo>−</mo></msubsup></math></span> levels are shifted in energy by <span><math><mo>−</mo><mfrac><mn>1</mn><mn>2</mn></mfrac><msub><mi>ν</mi><msub><mi>T</mi><mn>1</mn></msub></msub></math></span> and <span><math><mo>+</mo><mfrac><mn>1</mn><mn>2</mn></mfrac><msub><mi>ν</mi><msub><mi>T</mi><mn>1</mn></msub></msub></math></span>, respectively. The ab initio study identified a global minimum energy structure of C<sub>1</sub> symmetry and a metastable local minimum of C<sub>s</sub> symmetry. We computed the optimized geometries of four equivalent configurations in the m","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"409 ","pages":"Article 112010"},"PeriodicalIF":1.4,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143820648","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}
Pub Date : 2025-03-01DOI: 10.1016/j.jms.2025.112007
G.M. Chenard , A.G. Adam , D.W. Tokaryk , C. Linton
Laser Induced Fluorescence has been used to study the spectroscopy of Ruthenium Monoxide (RuO) in the UNB laser-ablation molecular-jet apparatus. High-resolution spectra of six bands from four previously obtained electronic transitions, [16.05]5 – X5Δ4, [16.19]4 - X5Δ4, [16.19]4 - X5Δ3 and [15.07]3 - X5Δ4 plus two previously unobserved transitions, [15.70]3 and [16.36]3 – X5Δ4, were obtained at a resolution 20 times higher than previous experiments. This enabled rotational structure of six individual RuO isotopologues, 96RuO, 99RuO, 100RuO, 101RuO, 102RuO and 104RuO to be well resolved and was used to examine detailed rotational and vibrational isotope effects. Hyperfine structure due to the nuclear spin I = 5/2 of 99Ru and 101Ru has also been well resolved and was a valuable aid in establishing the electron configurations of the electronic states. The difference in the hyperfine structure in the [16.05]5 and [16.19]4 states supported their assignment as the Ω = 5 and 4 spin orbit components, 5Φ5 and 5Φ4, of a single Hund's case (a) electronic state.
{"title":"Analysis of the rotational and hyperfine structure in the ‘red’ bands of ruthenium monoxide (RuO)","authors":"G.M. Chenard , A.G. Adam , D.W. Tokaryk , C. Linton","doi":"10.1016/j.jms.2025.112007","DOIUrl":"10.1016/j.jms.2025.112007","url":null,"abstract":"<div><div>Laser Induced Fluorescence has been used to study the spectroscopy of Ruthenium Monoxide (RuO) in the UNB laser-ablation molecular-jet apparatus. High-resolution spectra of six bands from four previously obtained electronic transitions, [16.05]5 – X<sup>5</sup>Δ<sub>4</sub>, [16.19]4 - X<sup>5</sup>Δ<sub>4</sub>, [16.19]4 - X<sup>5</sup>Δ<sub>3</sub> and [15.07]3 - X<sup>5</sup>Δ<sub>4</sub> plus two previously unobserved transitions, [15.70]3 and [16.36]3 – X<sup>5</sup>Δ<sub>4</sub>, were obtained at a resolution 20 times higher than previous experiments. This enabled rotational structure of six individual RuO isotopologues, <sup>96</sup>RuO, <sup>99</sup>RuO, <sup>100</sup>RuO, <sup>101</sup>RuO, <sup>102</sup>RuO and <sup>104</sup>RuO to be well resolved and was used to examine detailed rotational and vibrational isotope effects. Hyperfine structure due to the nuclear spin <em>I</em> = 5/2 of <sup>99</sup>Ru and <sup>101</sup>Ru has also been well resolved and was a valuable aid in establishing the electron configurations of the electronic states. The difference in the hyperfine structure in the [16.05]5 and [16.19]4 states supported their assignment as the Ω = 5 and 4 spin orbit components, <sup>5</sup>Φ<sub>5</sub> and <sup>5</sup>Φ<sub>4</sub>, of a single Hund's case (a) electronic state.</div></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"409 ","pages":"Article 112007"},"PeriodicalIF":1.4,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143746746","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}
Pub Date : 2025-03-01DOI: 10.1016/j.jms.2025.112008
Wafaa M. Fawzy
We developed new FORTRAN codes that employ two different Hamiltonians [Wafaa M. Fawzy, J. Mol. Spectrosc., 397, 111,822, 2023] for calculation of energy levels and relative intensities of rotational transitions in an asymmetric or a symmetric top weakly-bonded open-shell dimer. The type of complexes of interest consist of a polyatomic/diatomic closed-shell molecule and the O2 diradical in its ground electronic state, where the monomers experience rotation-tunneling motion. The programs set up the Hamiltonian matrix considering pure rotation, quartic and sextic centrifugal distortion terms, electron-spin electron-spin coupling, R-dependence of electron-spin constants, electron-spin-rotation interaction, a symmetry treatment for rotation-tunneling of the monomers, and dependence of the rotational constants on the rotation-tunneling state. Numerical diagonalization of the total Hamiltonian matrix in the molecular basis set provides the eigenvalues and the eigenfunctions. The eigenfunctions are used to transform expectation values of the parity, five quantum numbers (<P>, <K>, <N>, <Ps>, <Σ>), and the electric dipole moment matrix elements from the Hamiltonian basis set to the eigenfunctions basis of the complex. Calculations showed that goodness of the quantum numbers depends on geometry and relative values of the electron–spin electron–spin coupling constants, the rotational parameters, the tunneling splitting. We used the Hellman–Feynman theory for calculation of derivatives of the eigenvalues with respect to molecular parameters, which significantly reduces the computer time for the non-linear least squares fits of transitions. The FORTRAN suites of computer programs were tested and validated by fitting the high resolution IR and MW spectra of the O2–DF and the O2-SO2 dimers, respectively, with standard deviations within accuracy of the frequency measurement. However, the codes should be suitable for spectral analysis of any O2 -XY2 or O2 -XY cluster, where XY2 and XY represent a closed-shell non-linear triatomic molecule of C2v symmetry (e.g. H2O) and a diatomic entity (e.g. CO), respectively. The FORTRAN source programs, input and output files for spectral fits of the MW spectrum of O2-SO2 are discussed. In addition, zipped files of the suites of programs, the input and output files for fitting the MW spectrum of O2-SO2 and the IR spectrum of O2 -DF, respectively, are provided as supplements that can be downloaded.
我们开发了新的FORTRAN代码，使用两种不同的哈密顿量[Wafaa M. Fawzy， J. Mol. Spectrosc]。计算非对称或对称顶部弱键开壳二聚体的能级和旋转跃迁的相对强度[j]，[397, 111,822, 2023]。这种类型的配合物由一个多原子/双原子闭壳分子和处于基电子态的O2双自由基组成，其中单体经历了旋转隧道运动。程序建立了考虑纯旋转、四次和六次离心畸变项、电子-自旋耦合、电子-自旋常数的r依赖性、电子-自旋-自旋相互作用、单体旋转隧穿的对称处理以及旋转常数对旋转隧穿态的依赖性的哈密顿矩阵。对分子基集中的总哈密顿矩阵进行数值对角化，得到了特征值和特征函数。本征函数用于将宇称、五个量子数（<P>, <K>, <N>, <Ps>, <；Σ>）和电偶极矩矩阵元素的期望值从哈密顿基集合转换为复合体的本征函数基。计算表明，量子数的优劣取决于几何形状和电子-自旋耦合常数、旋转参数、隧穿分裂的相对值。我们使用Hellman-Feynman理论计算特征值相对于分子参数的导数，这大大减少了非线性最小二乘拟合过渡的计算机时间。通过拟合O2-DF和O2-SO2二聚体的高分辨率IR和MW光谱，在频率测量精度的标准偏差范围内，对FORTRAN计算机程序套件进行了测试和验证。然而，这些代码应该适用于任何O2 -XY2或O2 -XY簇的光谱分析，其中XY2和XY分别代表C2v对称的闭壳非线性三原子分子（例如H2O）和双原子实体（例如CO）。讨论了用于O2-SO2的MW谱拟合的FORTRAN源程序、输入和输出文件。此外，还提供了程序套件的压缩文件、O2- so2的MW谱拟合输入文件和O2 -DF的IR谱拟合输出文件作为补充，可供下载。
{"title":"Two codes for calculation of the rotation-spin-tunneling energy levels in the microwave and the infrared spectra of O2 (Σg-3)-XY2 open-shell complexes","authors":"Wafaa M. Fawzy","doi":"10.1016/j.jms.2025.112008","DOIUrl":"10.1016/j.jms.2025.112008","url":null,"abstract":"<div><div>We developed new FORTRAN codes that employ two different Hamiltonians [Wafaa M. Fawzy, J. Mol. Spectrosc., 397, 111,822, 2023] for calculation of energy levels and relative intensities of rotational transitions in an asymmetric or a symmetric top weakly-bonded open-shell dimer. The type of complexes of interest consist of a polyatomic/diatomic closed-shell molecule and the O<sub>2</sub> diradical in its ground electronic state, where the monomers experience rotation-tunneling motion. The programs set up the Hamiltonian matrix considering pure rotation, quartic and sextic centrifugal distortion terms, electron-spin electron-spin coupling, R-dependence of electron-spin constants, electron-spin-rotation interaction, a symmetry treatment for rotation-tunneling of the monomers, and dependence of the rotational constants on the rotation-tunneling state. Numerical diagonalization of the total Hamiltonian matrix in the molecular basis set provides the eigenvalues and the eigenfunctions. The eigenfunctions are used to transform expectation values of the parity, five quantum numbers (<P>, <K>, <N>, <P<sub>s</sub>>, <Σ>), and the electric dipole moment matrix elements from the Hamiltonian basis set to the eigenfunctions basis of the complex. Calculations showed that goodness of the quantum numbers depends on geometry and relative values of the electron–spin electron–spin coupling constants, the rotational parameters, the tunneling splitting. We used the Hellman–Feynman theory for calculation of derivatives of the eigenvalues with respect to molecular parameters, which significantly reduces the computer time for the non-linear least squares fits of transitions. The FORTRAN suites of computer programs were tested and validated by fitting the high resolution IR and MW spectra of the O<sub>2</sub>–DF and the O<sub>2</sub>-SO<sub>2</sub> dimers, respectively, with standard deviations within accuracy of the frequency measurement. However, the codes should be suitable for spectral analysis of any O<sub>2</sub> -XY<sub>2</sub> or O<sub>2</sub> -XY cluster, where XY<sub>2</sub> and XY represent a closed-shell non-linear triatomic molecule of C<sub>2</sub>v symmetry (e.g. H<sub>2</sub>O) and a diatomic entity (e.g. CO), respectively. The FORTRAN source programs, input and output files for spectral fits of the MW spectrum of O<sub>2</sub>-SO<sub>2</sub> are discussed. In addition, zipped files of the suites of programs, the input and output files for fitting the MW spectrum of O<sub>2</sub>-SO<sub>2</sub> and the IR spectrum of O<sub>2</sub> -DF, respectively, are provided as supplements that can be downloaded.</div></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"409 ","pages":"Article 112008"},"PeriodicalIF":1.4,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143817609","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}
Pub Date : 2025-03-01DOI: 10.1016/j.jms.2025.112009
Casper Vindahl Jensen, Emil Vogt, Henrik G. Kjaergaard
We have recorded gas-phase room-temperature absorption spectra of t-BuOOH in the OH-stretching regions, , using a combination of Fourier transform infrared spectroscopy and cavity ring-down spectroscopy. The t-BuOOH samples are phase-extracted into dichloromethane, which can be accurately accounted for by spectral subtraction. We thereby obtain spectra of pure t-BuOOH and corresponding sample partial pressures allowing us to obtain absolute intensities of the OH-stretching bands in all regions. The subtraction of solvents and impurities provides accurate values for the band intensities and positions. A reduced dimensional local mode model is invoked to corroborate the experimentally determined band oscillator strengths and their assignments. The fundamental OH-stretching band oscillator strength is determined to be about twice as large as the literature value. In the region, the intensity is spread out efficiently by a Franck–Condon-like mechanism to combination features associated with the OH-stretch and the COOH-torsion.
{"title":"Oscillator strengths of the fundamental and overtone OH-stretching bands of tert-butyl hydroperoxide in gas phase","authors":"Casper Vindahl Jensen, Emil Vogt, Henrik G. Kjaergaard","doi":"10.1016/j.jms.2025.112009","DOIUrl":"10.1016/j.jms.2025.112009","url":null,"abstract":"<div><div>We have recorded gas-phase room-temperature absorption spectra of <em>t</em>-BuOOH in the OH-stretching regions, <span><math><mrow><mi>Δ</mi><msub><mrow><mi>v</mi></mrow><mrow><mi>O</mi><mi>H</mi></mrow></msub><mo>=</mo><mn>1</mn><mo>−</mo><mn>5</mn></mrow></math></span>, using a combination of Fourier transform infrared spectroscopy and cavity ring-down spectroscopy. The <em>t</em>-BuOOH samples are phase-extracted into dichloromethane, which can be accurately accounted for by spectral subtraction. We thereby obtain spectra of pure <em>t</em>-BuOOH and corresponding sample partial pressures allowing us to obtain absolute intensities of the OH-stretching bands in all regions. The subtraction of solvents and impurities provides accurate values for the band intensities and positions. A reduced dimensional local mode model is invoked to corroborate the experimentally determined band oscillator strengths and their assignments. The fundamental OH-stretching band oscillator strength is determined to be <span><math><mrow><mrow><mo>(</mo><mn>4</mn><mo>.</mo><mn>56</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>15</mn><mo>)</mo></mrow><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>6</mn></mrow></msup></mrow></math></span> about twice as large as the literature value. In the <span><math><mrow><mi>Δ</mi><msub><mrow><mi>v</mi></mrow><mrow><mi>O</mi><mi>H</mi></mrow></msub><mo>=</mo><mn>5</mn></mrow></math></span> region, the intensity is spread out efficiently by a Franck–Condon-like mechanism to combination features associated with the OH-stretch and the COOH-torsion.</div></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"409 ","pages":"Article 112009"},"PeriodicalIF":1.4,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143776793","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}
Pub Date : 2025-03-01DOI: 10.1016/j.jms.2025.112006
Tokio Yukiya, Shinji Kobayashi, Katsuki Nomura, Nobuo Nishimiya
Doppler-limited vibrational absorption spectra of the AX electronic transition of IBr are measured in the 0.695 – and the 0.90 – region using a Ti:sapphire ring laser. The absorption lines belonging to (0,1) and (6,7) for IBr are assigned, and the center position of the branch line belonging to over =21, which is split into a doublet by the electric quadrupole coupling effect, was estimated. The potential models and function parameters for the and states in IBr were determined using direct potential fitting.
{"title":"Direct potential fitting analysis for the A3Π1←X1Σ+ system of IBr","authors":"Tokio Yukiya, Shinji Kobayashi, Katsuki Nomura, Nobuo Nishimiya","doi":"10.1016/j.jms.2025.112006","DOIUrl":"10.1016/j.jms.2025.112006","url":null,"abstract":"<div><div>Doppler-limited vibrational absorption spectra of the <em>A</em> <span><math><mo>←</mo></math></span> <em>X</em> electronic transition of I<span><math><msup><mrow></mrow><mrow><mn>79</mn><mo>/</mo><mn>81</mn></mrow></msup></math></span>Br are measured in the 0.695 – <span><math><mrow><mn>0</mn><mo>.</mo><mn>735</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span> and the 0.90 – <span><math><mrow><mn>0</mn><mo>.</mo><mn>94</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span> region using a Ti:sapphire ring laser. The absorption lines belonging to <span><math><mrow><msup><mrow><mi>v</mi></mrow><mrow><mo>′</mo></mrow></msup><mo>←</mo><msup><mrow><mi>v</mi></mrow><mrow><mo>′</mo><mo>′</mo></mrow></msup><mo>=</mo><msup><mrow><mrow><mo>(</mo><mn>19</mn><mo>−</mo><mn>32</mn><mo>)</mo></mrow></mrow><mrow><mo>′</mo></mrow></msup></mrow></math></span> <span><math><mo>←</mo></math></span> (0,1)<span><math><msup><mrow></mrow><mrow><mo>′</mo><mo>′</mo></mrow></msup></math></span> and <span><math><msup><mrow><mrow><mo>(</mo><mn>2</mn><mo>,</mo><mn>3</mn><mo>,</mo><mn>4</mn><mo>)</mo></mrow></mrow><mrow><mo>′</mo></mrow></msup></math></span> <span><math><mo>←</mo></math></span> (6,7)<span><math><msup><mrow></mrow><mrow><mo>′</mo><mo>′</mo></mrow></msup></math></span> for I<span><math><msup><mrow></mrow><mrow><mn>79</mn><mo>/</mo><mn>81</mn></mrow></msup></math></span>Br are assigned, and the center position of the <span><math><mi>Q</mi></math></span> branch line belonging to over <span><math><msup><mrow><mi>v</mi></mrow><mrow><mo>′</mo></mrow></msup></math></span>=21, which is split into a doublet by the electric quadrupole coupling effect, was estimated. The potential models and function parameters for the <span><math><mrow><msup><mrow><mi>A</mi></mrow><mrow><mn>3</mn></mrow></msup><msub><mrow><mi>Π</mi></mrow><mrow><mn>1</mn></mrow></msub></mrow></math></span> and <span><math><mrow><msup><mrow><mi>X</mi></mrow><mrow><mn>1</mn></mrow></msup><msup><mrow><mi>Σ</mi></mrow><mrow><mo>+</mo></mrow></msup></mrow></math></span> states in I<span><math><msup><mrow></mrow><mrow><mn>79</mn><mo>/</mo><mn>81</mn></mrow></msup></math></span>Br were determined using direct potential fitting.</div></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"409 ","pages":"Article 112006"},"PeriodicalIF":1.4,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143799037","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}
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