Pub Date : 2024-10-16DOI: 10.1016/j.jms.2024.111955
D.M. Plastinina , A.S. Lipskaya , E.N. Chesnokov
The frequencies of C2HD hot bands ro-vibrational lines of the first overtone of C-H stretching were measured using tunable diode lasers. To expand the measuring range to the region of the large rotational numbers, a heated gas cell was used. Measurements were made in the range R1–R36 and P2–P14 for the transition (2,0,0,1,0) ← (0,0,0,1,0), and in the range R1–R18 for the transition (2,0,0,0,1) ← (0,0,0,0,1). The rotational parameters of the upper and lower states for the band (2,0,0,1,0) ← (0,0,0,1,0) were determined. The doublet structure of ro-vibrational lines was studied. For the transition (2,0,0,1,0) ← (0,0,0,1,0), a sharp increase in the splitting value was detected at J > 25.
{"title":"High resolution laser diode spectroscopy of the hot bands of C2HD in the first overtone region of C-H stretching","authors":"D.M. Plastinina , A.S. Lipskaya , E.N. Chesnokov","doi":"10.1016/j.jms.2024.111955","DOIUrl":"10.1016/j.jms.2024.111955","url":null,"abstract":"<div><div>The frequencies of C<sub>2</sub>HD hot bands ro-vibrational lines of the first overtone of C-H stretching were measured using tunable diode lasers. To expand the measuring range to the region of the large rotational numbers, a heated gas cell was used. Measurements were made in the range R1–R36 and P2–P14 for the transition (2,0,0,1,0) ← (0,0,0,1,0), and in the range R1–R18 for the transition (2,0,0,0,1) ← (0,0,0,0,1). The rotational parameters of the upper and lower states for the band (2,0,0,1,0) ← (0,0,0,1,0) were determined. The doublet structure of ro-vibrational lines was studied. For the transition (2,0,0,1,0) ← (0,0,0,1,0), a sharp increase in the splitting value was detected at J > 25.</div></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"406 ","pages":"Article 111955"},"PeriodicalIF":1.4,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535262","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 : 2024-10-11DOI: 10.1016/j.jms.2024.111952
Joshua E. Isert , Josie R. Glenn , S.A. Cooke , G.S. Grubbs II
Pure rotational transitions for HfS and ThS have been measured in highly excited vibrational states. For HfS, rotational transitions have been recorded in up to the 19th excited vibrational state, whereas for ThS measurements extend up to the 17th excited vibrational state. Pure rotational transitions have also been recorded for Th34S for the first time. In both cases isotopically invariant analyses have been performed and very accurate equilibrium bond lengths have been determined.
{"title":"Pure rotational spectroscopic measurements on the electronic ground states of Hafnium monosulfide and Thorium monosulfide in highly excited vibrational states","authors":"Joshua E. Isert , Josie R. Glenn , S.A. Cooke , G.S. Grubbs II","doi":"10.1016/j.jms.2024.111952","DOIUrl":"10.1016/j.jms.2024.111952","url":null,"abstract":"<div><div>Pure rotational transitions for HfS and ThS have been measured in highly excited vibrational states. For HfS, rotational transitions have been recorded in up to the 19th excited vibrational state, whereas for ThS measurements extend up to the 17th excited vibrational state. Pure rotational transitions have also been recorded for Th<sup>34</sup>S for the first time. In both cases isotopically invariant analyses have been performed and very accurate equilibrium bond lengths have been determined.</div></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"406 ","pages":"Article 111952"},"PeriodicalIF":1.4,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535261","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 : 2024-10-11DOI: 10.1016/j.jms.2024.111953
Thomas Howard, Shannon E. Ganley, Sanjana Maheshwari, Leah G. Dodson
We describe an instrument that uses continuous-wave (CW) cavity-ringdown spectroscopy to measure the translational and rotational temperature of buffer-gas cooled molecules and demonstrate its use on hydrogen cyanide. This instrument can access the near-infrared region around 1.5 μm—a rich spectral region that features the rotationally resolved first overtone of the C-H stretch for many astrophysically relevant molecules. Molecules are probed directly inside the buffer-gas cell, further enabling quantitative measurements of the effectiveness of this cooling technique.
{"title":"Buffer-gas cooling of hydrogen cyanide quantified by cavity-ringdown spectroscopy","authors":"Thomas Howard, Shannon E. Ganley, Sanjana Maheshwari, Leah G. Dodson","doi":"10.1016/j.jms.2024.111953","DOIUrl":"10.1016/j.jms.2024.111953","url":null,"abstract":"<div><div>We describe an instrument that uses continuous-wave (CW) cavity-ringdown spectroscopy to measure the translational and rotational temperature of buffer-gas cooled molecules and demonstrate its use on hydrogen cyanide. This instrument can access the near-infrared region around 1.5 μm—a rich spectral region that features the rotationally resolved first overtone of the C-H stretch for many astrophysically relevant molecules. Molecules are probed directly inside the buffer-gas cell, further enabling quantitative measurements of the effectiveness of this cooling technique.</div></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"406 ","pages":"Article 111953"},"PeriodicalIF":1.4,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535260","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 : 2024-10-11DOI: 10.1016/j.jms.2024.111954
Zbigniew Kisiel
<div><div>The present work fills several significant gaps in the study of the rotational spectrum of the methylene chloride molecule. Two Fourier transform microwave spectrometers were used, providing complementary coverage of the 8–18 GHz region, at room temperature and in supersonic expansion. Hyperfine resolved measurements were made and fitted for ground states of the CH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span><sup>35</sup>Cl<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><sup>35</sup>Cl<sup>37</sup>Cl, CH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span><sup>37</sup>Cl<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>, and <sup>13</sup>CH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span><sup>35</sup>Cl<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> isotopic species, as well as for nine different excited vibrational states. Transitions in the <span><math><mrow><msub><mrow><mi>v</mi></mrow><mrow><mn>4</mn></mrow></msub><mo>=</mo><mn>2</mn></mrow></math></span>, <span><math><mrow><msub><mrow><mi>v</mi></mrow><mrow><mn>4</mn></mrow></msub><mo>=</mo><mn>3</mn></mrow></math></span>, <span><math><mrow><msub><mrow><mi>v</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>=</mo><mn>1</mn></mrow></math></span>, <span><math><mrow><msub><mrow><mi>v</mi></mrow><mrow><mn>9</mn></mrow></msub><mo>=</mo><mn>1</mn></mrow></math></span> states in CH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span><sup>35</sup>Cl<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>, and transitions in excited states of the <span><math><msub><mrow><mi>ν</mi></mrow><mrow><mn>4</mn></mrow></msub></math></span> mode in <sup>35</sup>Cl<sup>37</sup>Cl and <sup>37</sup>Cl<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> isotopic species have been assigned for the first time. Vibrational and isotopic dependence of nuclear quadrupole coupling constants was identified. The <span><math><mrow><msub><mrow><mi>v</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>=</mo><mn>1</mn></mrow></math></span> and <span><math><mrow><msub><mrow><mi>v</mi></mrow><mrow><mn>9</mn></mrow></msub><mo>=</mo><mn>1</mn></mrow></math></span> states in CH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span><sup>35</sup>Cl<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> were found to be significantly coupled by <span><math><mi>c</mi></math></span>-axis Coriolis interaction, while transitions in <span><math><mrow><msub><mrow><mi>v</mi></mrow><mrow><mn>4</mn></mrow></msub><mo>=</mo><mn>2</mn></mrow></math></span> and <span><math><mrow><msub><mrow><mi>v</mi></mrow><mrow><mn>4</mn></mrow></msub><mo>=</mo><mn>3</mn></mrow></math></span> states exhibited hyperfine mediated p
{"title":"Isotopic species, vibrational states and nuclear quadrupole splitting in CH2Cl2 from rotational spectroscopy at 8–18 GHz","authors":"Zbigniew Kisiel","doi":"10.1016/j.jms.2024.111954","DOIUrl":"10.1016/j.jms.2024.111954","url":null,"abstract":"<div><div>The present work fills several significant gaps in the study of the rotational spectrum of the methylene chloride molecule. Two Fourier transform microwave spectrometers were used, providing complementary coverage of the 8–18 GHz region, at room temperature and in supersonic expansion. Hyperfine resolved measurements were made and fitted for ground states of the CH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span><sup>35</sup>Cl<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><sup>35</sup>Cl<sup>37</sup>Cl, CH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span><sup>37</sup>Cl<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>, and <sup>13</sup>CH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span><sup>35</sup>Cl<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> isotopic species, as well as for nine different excited vibrational states. Transitions in the <span><math><mrow><msub><mrow><mi>v</mi></mrow><mrow><mn>4</mn></mrow></msub><mo>=</mo><mn>2</mn></mrow></math></span>, <span><math><mrow><msub><mrow><mi>v</mi></mrow><mrow><mn>4</mn></mrow></msub><mo>=</mo><mn>3</mn></mrow></math></span>, <span><math><mrow><msub><mrow><mi>v</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>=</mo><mn>1</mn></mrow></math></span>, <span><math><mrow><msub><mrow><mi>v</mi></mrow><mrow><mn>9</mn></mrow></msub><mo>=</mo><mn>1</mn></mrow></math></span> states in CH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span><sup>35</sup>Cl<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>, and transitions in excited states of the <span><math><msub><mrow><mi>ν</mi></mrow><mrow><mn>4</mn></mrow></msub></math></span> mode in <sup>35</sup>Cl<sup>37</sup>Cl and <sup>37</sup>Cl<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> isotopic species have been assigned for the first time. Vibrational and isotopic dependence of nuclear quadrupole coupling constants was identified. The <span><math><mrow><msub><mrow><mi>v</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>=</mo><mn>1</mn></mrow></math></span> and <span><math><mrow><msub><mrow><mi>v</mi></mrow><mrow><mn>9</mn></mrow></msub><mo>=</mo><mn>1</mn></mrow></math></span> states in CH<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span><sup>35</sup>Cl<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span> were found to be significantly coupled by <span><math><mi>c</mi></math></span>-axis Coriolis interaction, while transitions in <span><math><mrow><msub><mrow><mi>v</mi></mrow><mrow><mn>4</mn></mrow></msub><mo>=</mo><mn>2</mn></mrow></math></span> and <span><math><mrow><msub><mrow><mi>v</mi></mrow><mrow><mn>4</mn></mrow></msub><mo>=</mo><mn>3</mn></mrow></math></span> states exhibited hyperfine mediated p","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"406 ","pages":"Article 111954"},"PeriodicalIF":1.4,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142535263","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}
Pub Date : 2024-10-01DOI: 10.1016/j.jms.2024.111951
Nan Fang , Chuan-Yu Zhang , Ming-Jie Wan , Xiao-Peng Huang
The molecular potential energy function plays an important role in many fields. In this paper, the icMRCI + Q method was utilized to compute the potential energy and dipole moments for 22 Λ-S states and 51 Ω states of the TeI+ system. Two basis sets (AVQZ-PP and AWCVQZ-PP) were employed to compute the TeI+ system, with the results indicating that the AVQZ-PP basis set yielded more accurate results. Therefore, all calculations in this paper are based on this basis set. Furthermore, to ensure the accuracy of the results, a comparison was conducted on the spectral parameters of the ground state and two excited states of the molecular ion within the same main group. Given the significant impact of spin–orbit coupling, as indicated by the calculated SO matrix elements, our discussion will predominantly center on the avoidance of crossovers in the Ω states. Finally, the Franck-Condon factors, Einstein coefficients and radiative lifetime between these two states were calculated from the data of the transition between the of the TeI+ molecule.
{"title":"Theoretical study on the spectrum properties of tellurium iodide cation","authors":"Nan Fang , Chuan-Yu Zhang , Ming-Jie Wan , Xiao-Peng Huang","doi":"10.1016/j.jms.2024.111951","DOIUrl":"10.1016/j.jms.2024.111951","url":null,"abstract":"<div><div>The molecular potential energy function plays an important role in many fields. In this paper, the icMRCI + Q method was utilized to compute the potential energy and dipole moments for 22 Λ-S states and 51 Ω states of the TeI<sup>+</sup> system. Two basis sets (AVQZ-PP and AWCVQZ-PP) were employed to compute the TeI<sup>+</sup> system, with the results indicating that the AVQZ-PP basis set yielded more accurate results. Therefore, all calculations in this paper are based on this basis set. Furthermore, to ensure the accuracy of the results, a comparison was conducted on the spectral parameters of the ground state and two excited states of the molecular ion within the same main group. Given the significant impact of spin–orbit coupling, as indicated by the calculated SO matrix elements, our discussion will predominantly center on the avoidance of crossovers in the Ω states. Finally, the Franck-Condon factors, Einstein coefficients and radiative lifetime between these two states were calculated from the data of the transition between the <span><math><mrow><msup><mi>X</mi><mn>3</mn></msup><msubsup><mi>Σ</mi><mrow><msup><mn>0</mn><mo>+</mo></msup></mrow><mo>-</mo></msubsup><mo>↔</mo><msup><mn>1</mn><mn>1</mn></msup><msubsup><mi>Σ</mi><mrow><msup><mn>0</mn><mo>+</mo></msup></mrow><mo>+</mo></msubsup></mrow></math></span> of the TeI<sup>+</sup> molecule.</div></div>","PeriodicalId":16367,"journal":{"name":"Journal of Molecular Spectroscopy","volume":"405 ","pages":"Article 111951"},"PeriodicalIF":1.4,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426406","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 : 2024-10-01DOI: 10.1016/j.jms.2024.111950
Sven Herbers
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 XIAM 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 J, has now been enhanced. The updated version, XIAM-NQ, 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 XIAM-NQ is demonstrated on o-halotoluenes and m-chlorotoluene.
{"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}
Pub Date : 2024-10-01DOI: 10.1016/j.jms.2024.111948
Ryan Welch , Mark D. Marshall , Eva Gougoula , Nicholas R. Walker , Helen O. Leung
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 S-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, R. 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.
傅立叶变换微波光谱法记录了氩原子和咪唑（Ar...imidazole）之间形成的孤立复合物的四种同素异形体在 6-19 GHz 区域的旋转光谱。旋转转变频率被拟合到沃森的 S 还原汉密尔顿方程中，从而得出了复合物的旋转、离心变形和核四极耦合常数。根据母体和三个含 15N 的同素异形体确定的旋转常数可以描述复合物的三维结构。除了 Ar 与咪唑亚基的质心 R 之间的距离外，还首次测定了确定 Ar 原子相对于咪唑环的取向的两个角度 θ 和 ϕ。将结构参数与实验测定的惯性矩拟合，得到的结构是 Ar 位于环平面之上，与咪唑亚基的质心距离为 3.519 Å。在实验确定的平均几何结构中，分子间轴（通过 Ar 和咪唑亚基的质心）的方向与环平面的法线成 6°。实验结果为 ϕ 提供了四种可能性，其中 62.0(39)° 最符合以前工作中对该参数的预期。实验确定的核四极耦合常数意味着，在与 Ar 形成复合物时，咪唑的每个氮核的电场梯度不会发生显著变化。
{"title":"Geometry of the argon…imidazole complex revealed by the microwave spectra of four isotopologues","authors":"Ryan Welch , Mark D. Marshall , Eva Gougoula , Nicholas R. Walker , 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 <sup>15</sup>N-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}
Pub Date : 2024-09-24DOI: 10.1016/j.jms.2024.111949
Adam M. Daly , Kristen K. Roehling , Rhett P. Hill , Myla G. Gonzalez , Xin Kang , Lisa McElwee-White , Stephen G. Kukolich
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 dJ 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 1.5χaa = 98.12(17) MHz and 0.25(χbb-χcc) = 36.059(30). Measured hyperfine structure splittings for 99Ru quadrupole coupling yielded the values of 1.5χaa = 16.99(77) MHz and 0.25(χbb-χcc) = 6.23(32). These values are in reasonable agreement with some of the all-electron calculations.
{"title":"Microwave spectrum and molecular structure calculations for η4-butadiene ruthenium tricarbonyl","authors":"Adam M. Daly , Kristen K. Roehling , Rhett P. Hill , Myla G. Gonzalez , Xin Kang , Lisa McElwee-White , 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 η<sup>4</sup>-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 <sup>102</sup>Ru 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<sub>J</sub> 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 <sup>101</sup>Ru and <sup>99</sup>Ru quadrupole coupling strengths. Quadrupole hyperfine structure splittings were measured for both <sup>101</sup>Ru and <sup>99</sup>Ru. The hyperfine structure splittings for the <sup>101</sup>Ru nuclear quadrupole were measured, yielding the values of 1.5χ<sub>aa</sub> = 98.12(17) MHz and 0.25(χ<sub>bb</sub>-χ<sub>cc</sub>) = 36.059(30). Measured hyperfine structure splittings for <sup>99</sup>Ru quadrupole coupling yielded the values of 1.5χ<sub>aa</sub> = 16.99(77) MHz and 0.25(χ<sub>bb</sub>-χ<sub>cc</sub>) = 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}
Pub Date : 2024-09-14DOI: 10.1016/j.jms.2024.111947
Ala’a A.A. Azzam , Sumaya A.A. Azzam , Karam A.A. Aburumman , Jonathan Tennyson , Sergei N. Yurchenko , Attila G. Császár , Tibor Furtenbacher
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.
{"title":"MARVEL analysis of high-resolution rovibrational spectra of the 18O12C18O, 17O12C18O, and 18O13C18O isotopologues of carbon dioxide","authors":"Ala’a A.A. Azzam , Sumaya A.A. Azzam , Karam A.A. Aburumman , Jonathan Tennyson , Sergei N. Yurchenko , Attila G. Császár , 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, <sup>18</sup>O<sup>12</sup>C<sup>18</sup>O (828, according to a well-established shorthand notation), <sup>17</sup>O<sup>12</sup>C<sup>18</sup>O (728), and <sup>18</sup>O<sup>13</sup>C<sup>18</sup>O (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<sup>−1</sup> (for 828), 628–8197 cm<sup>−1</sup> (for 728), and 600–7918 cm<sup>−1</sup> (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 CO<sub>2</sub>, 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}
Pub Date : 2024-09-01DOI: 10.1016/j.jms.2024.111938
Prashansa B. Kannangara , Hannah L. Fino , Channing T. West , Brooks H. Pate , Sean A. Peebles , Rebecca A. Peebles
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 A-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 ωB97X-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.
{"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 , Hannah L. Fino , Channing T. West , Brooks H. Pate , Sean A. Peebles , 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)/CO<sub>2</sub> clusters, (FE)<sub>x</sub>(CO<sub>2</sub>)<sub>y</sub>, with x from 1 to 4 and y from 0 to 4. Multiple spectra were recorded with varying concentrations of CO<sub>2</sub> 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:CO<sub>2</sub> 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}
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