F. Lorin, Anh H. M. Nguyen, A. Gutiérrez-Quintanilla, A. I. Strom, J. Ceponkus, D. T. Anderson, C. Crépin
Samples of propyne trapped in solid parahydrogen show multiple peak structures in their infrared spectra. These structures are attributed to molecules in two distinct kinds of matrix sites. The most intense lines are assigned to propyne molecules executing a slightly hindered methyl rotation, as was extensively studied in our earlier publication from our two groups, and the other set of peaks to propyne trapped in a secondary site where the methyl rotation is quenched and replaced by methyl torsion within the matrix site. The assignment of the various rovibrational transitions is made possible by the observation of nuclear spin conversion (NSC) within the methyl group at long timescales. The NSC rate depends on the site and is much slower in the sites where the methyl rotation is quenched.
{"title":"Propyne confinement in solid parahydrogen: Methyl rotation and site effects","authors":"F. Lorin, Anh H. M. Nguyen, A. Gutiérrez-Quintanilla, A. I. Strom, J. Ceponkus, D. T. Anderson, C. Crépin","doi":"10.1063/10.0028174","DOIUrl":"https://doi.org/10.1063/10.0028174","url":null,"abstract":"Samples of propyne trapped in solid parahydrogen show multiple peak structures in their infrared spectra. These structures are attributed to molecules in two distinct kinds of matrix sites. The most intense lines are assigned to propyne molecules executing a slightly hindered methyl rotation, as was extensively studied in our earlier publication from our two groups, and the other set of peaks to propyne trapped in a secondary site where the methyl rotation is quenched and replaced by methyl torsion within the matrix site. The assignment of the various rovibrational transitions is made possible by the observation of nuclear spin conversion (NSC) within the methyl group at long timescales. The NSC rate depends on the site and is much slower in the sites where the methyl rotation is quenched.","PeriodicalId":18077,"journal":{"name":"Low Temperature Physics","volume":"16 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142201126","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}
Jay C. Amicangelo, Natalie C. Romano, Geoffrey R. Demay, Ian E. Campbell, Joshua D. Wilkins
Matrix isolation infrared spectroscopy was used to characterize a 1:1 complex of methanol (CH3OH) and benzene (C6H6). Co-deposition experiments with CH3OH and C6H6 were performed at 17–20 K using nitrogen and argon as the matrix gases. Several new infrared peaks in the co-deposition spectra were observed near the fundamental absorptions of the CH3OH and C6H6 parent molecules and these new peaks have been attributed to CH3OH–C6H6 complexe. Experiments were also performed with isotopic CD3OD and C6D6 and the corresponding infrared peaks of the isotopologue complexes have also been observed. Theoretical calculations were performed for the CH3OH–C6H6 complex using the M06-2X, ωB97X-D, MP2, and CCSD(T) methods with the aug-cc-pVDZ and aug-cc-pVTZ basis sets. Full geometry optimizations followed by vibrational frequency calculations were performed for several initial starting geometries and three stable minima were found for the CH3OH–C6H6 complex. The first has the CH3OH above the C6H6 ring with the OH hydrogen interacting with the π cloud of the ring (H–π complex), the second has the CH3OH above the C6H6 ring with the OH oxygen interacting with one or two of the C–H bonds of the ring (CH–O 1 complex), and the third has the CH3OH towards the side of the C6H6 ring with the OH oxygen interacting with two of the C–H bonds of the ring (CH–O 2 complex). The H–π complex structure is predicted to be the lower energy structure by ∼8 kJ/mol compared to the two CH–O structures. Comparing the theoretically predicted infrared spectra for the optimized CH3OH–C6H6 complex structures to the experimentally observed infrared peaks in argon and nitrogen matrices, it is concluded that in the argon matrices only the H–π complex structure is being observed, whereas in the nitrogen matrices the H–π complex and CH–O 1 complex structures are being observed.
{"title":"Characterization of H–π and CH–O structures of the 1:1 methanol-benzene complex using matrix isolation infrared spectroscopy","authors":"Jay C. Amicangelo, Natalie C. Romano, Geoffrey R. Demay, Ian E. Campbell, Joshua D. Wilkins","doi":"10.1063/10.0028186","DOIUrl":"https://doi.org/10.1063/10.0028186","url":null,"abstract":"Matrix isolation infrared spectroscopy was used to characterize a 1:1 complex of methanol (CH3OH) and benzene (C6H6). Co-deposition experiments with CH3OH and C6H6 were performed at 17–20 K using nitrogen and argon as the matrix gases. Several new infrared peaks in the co-deposition spectra were observed near the fundamental absorptions of the CH3OH and C6H6 parent molecules and these new peaks have been attributed to CH3OH–C6H6 complexe. Experiments were also performed with isotopic CD3OD and C6D6 and the corresponding infrared peaks of the isotopologue complexes have also been observed. Theoretical calculations were performed for the CH3OH–C6H6 complex using the M06-2X, ωB97X-D, MP2, and CCSD(T) methods with the aug-cc-pVDZ and aug-cc-pVTZ basis sets. Full geometry optimizations followed by vibrational frequency calculations were performed for several initial starting geometries and three stable minima were found for the CH3OH–C6H6 complex. The first has the CH3OH above the C6H6 ring with the OH hydrogen interacting with the π cloud of the ring (H–π complex), the second has the CH3OH above the C6H6 ring with the OH oxygen interacting with one or two of the C–H bonds of the ring (CH–O 1 complex), and the third has the CH3OH towards the side of the C6H6 ring with the OH oxygen interacting with two of the C–H bonds of the ring (CH–O 2 complex). The H–π complex structure is predicted to be the lower energy structure by ∼8 kJ/mol compared to the two CH–O structures. Comparing the theoretically predicted infrared spectra for the optimized CH3OH–C6H6 complex structures to the experimentally observed infrared peaks in argon and nitrogen matrices, it is concluded that in the argon matrices only the H–π complex structure is being observed, whereas in the nitrogen matrices the H–π complex and CH–O 1 complex structures are being observed.","PeriodicalId":18077,"journal":{"name":"Low Temperature Physics","volume":"3 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142201079","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}
High-resolution absorption spectra of the S1←S0000 transition of buffer-gas-cooled magnesium-phthalocyanine, zinc-phthalocyanine, and chloroaluminum-phthalocyanine are presented. The low temperature achieved through buffer gas cooling allowed the observation of a partially resolved rotational structure in each spectrum. We compare these structures with the previously observed high-resolution spectrum of free-base phthalocyanine. Despite the similar molecular structures of these molecules, the spectral characteristics of the rotational envelope vary depending on the individual molecular structures.
{"title":"High-resolution electronic spectroscopy of buffer-gas-cooled metal-phthalocyanines","authors":"Yuki Miyamoto, Masaaki Baba, Katsunari Enomoto, Ayami Hiramoto, Kana Iwakuni, Susumu Kuma","doi":"10.1063/10.0028188","DOIUrl":"https://doi.org/10.1063/10.0028188","url":null,"abstract":"High-resolution absorption spectra of the S1←S0000 transition of buffer-gas-cooled magnesium-phthalocyanine, zinc-phthalocyanine, and chloroaluminum-phthalocyanine are presented. The low temperature achieved through buffer gas cooling allowed the observation of a partially resolved rotational structure in each spectrum. We compare these structures with the previously observed high-resolution spectrum of free-base phthalocyanine. Despite the similar molecular structures of these molecules, the spectral characteristics of the rotational envelope vary depending on the individual molecular structures.","PeriodicalId":18077,"journal":{"name":"Low Temperature Physics","volume":"10 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142201082","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}
Thomas G. Custer, Claudine Crépin, Marcin Gronowski, Arun-Libertsen Lawzer, Robert Kołos
Isotopic (2H and 15N) labelling and IR absorption spectroscopy have been used to study UV-induced transformations of cyanoacetylene in cryogenic noble gas matrices. The results obtained indicate that all observed isomerization processes involve single, isolated molecules of the precursor. No photoproducts have been found that would imply the recombination of fragments originating from different molecules.
{"title":"Photochemistry of cyanoacetylene in solid argon revisited","authors":"Thomas G. Custer, Claudine Crépin, Marcin Gronowski, Arun-Libertsen Lawzer, Robert Kołos","doi":"10.1063/10.0028163","DOIUrl":"https://doi.org/10.1063/10.0028163","url":null,"abstract":"Isotopic (2H and 15N) labelling and IR absorption spectroscopy have been used to study UV-induced transformations of cyanoacetylene in cryogenic noble gas matrices. The results obtained indicate that all observed isomerization processes involve single, isolated molecules of the precursor. No photoproducts have been found that would imply the recombination of fragments originating from different molecules.","PeriodicalId":18077,"journal":{"name":"Low Temperature Physics","volume":"728 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142201116","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}
O. Korostyshevskyi, C. K. Wetzel, D. M. Lee, V. V. Khmelenko
We studied luminescence accompanied an injection of the nitrogen-helium gas mixture after passing discharge into dense cold helium gas. Initially, when the experimental beaker was filled with superfluid helium and the nitrogen-helium gas was injected into bulk superfluid helium at T ≈ 1.5 K, the dominant band in the emission spectra was the α-group of nitrogen atoms. At these conditions, the nanoclusters of molecular nitrogen with high concentrations of stabilized nitrogen atoms were formed. When superfluid helium was evaporated from the beaker and the temperature at the bottom of the beaker was increased to T ≈ 20 K, we observed a drastic change in the luminescence spectra. The β-group of oxygen atoms was dominated in the luminescence spectra, and the emission of the α-group became small. At high temperatures (T ≈ 20 K), most of the nitrogen atoms recombine on the surface of N2 nanoclusters with the formation of excited nitrogen molecules. We explained the effect of the enhancement of β-group emission by effective energy transfer from excited nitrogen molecules to the stabilized impurity oxygen atom inside N2 nanoclusters.
{"title":"Enhanced luminescence of oxygen atoms in solid molecular nitrogen nanoclusters","authors":"O. Korostyshevskyi, C. K. Wetzel, D. M. Lee, V. V. Khmelenko","doi":"10.1063/10.0028138","DOIUrl":"https://doi.org/10.1063/10.0028138","url":null,"abstract":"We studied luminescence accompanied an injection of the nitrogen-helium gas mixture after passing discharge into dense cold helium gas. Initially, when the experimental beaker was filled with superfluid helium and the nitrogen-helium gas was injected into bulk superfluid helium at T ≈ 1.5 K, the dominant band in the emission spectra was the α-group of nitrogen atoms. At these conditions, the nanoclusters of molecular nitrogen with high concentrations of stabilized nitrogen atoms were formed. When superfluid helium was evaporated from the beaker and the temperature at the bottom of the beaker was increased to T ≈ 20 K, we observed a drastic change in the luminescence spectra. The β-group of oxygen atoms was dominated in the luminescence spectra, and the emission of the α-group became small. At high temperatures (T ≈ 20 K), most of the nitrogen atoms recombine on the surface of N2 nanoclusters with the formation of excited nitrogen molecules. We explained the effect of the enhancement of β-group emission by effective energy transfer from excited nitrogen molecules to the stabilized impurity oxygen atom inside N2 nanoclusters.","PeriodicalId":18077,"journal":{"name":"Low Temperature Physics","volume":"19 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142201118","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}
The IR and UV absorption spectra of CO2+ isolated in solid neon were studied by using our newly built mass-selective matrix isolation system. The IR absorption spectrum revealed the formation of CO2 in both cationic and anionic forms in solid Ne, since neutral CO2 was also used to serve as an electron scavenger in this study. Subsequently, we recorded the UV absorption spectrum of the same matrix sample in the spectral region 270−400 nm, encompassing the electronic transitions of CO2+ from the ground state to the first two electronic excited states. Notably, the observation of the electronic transition A2Πu←X2Πg was dominated by the vibrational progression of the symmetric CO stretching mode, while a single sharp band was observed in the electronic transition B2Σu+←X2Πg. The presented spectra might be useful for future studies on terrestrial and astrochemical conjunctions.
我们利用新建立的质量选择性基质分离系统研究了在固体氖中分离出的 CO2+ 的红外和紫外吸收光谱。红外吸收光谱显示在固体氖中形成了阳离子和阴离子形式的 CO2，因为在本研究中中性 CO2 也被用作电子清除剂。随后，我们记录了同一基质样品在 270-400 nm 光谱区的紫外吸收光谱，其中包括 CO2+ 从基态到前两个电子激发态的电子跃迁。值得注意的是，对电子跃迁 A2Πu←X2Πg 的观察主要是对称 CO 伸展模式的振动进展，而在电子跃迁 B2Σu+←X2Πg 中则观察到一个单尖锐带。所提供的光谱可能有助于今后对陆地和天体化学结合的研究。
{"title":"Direct UV absorption spectra of CO2+ in solid neon","authors":"Wen-Jian Huang, Sheng-Lung Chou, Shu-Yu Lin, Hui-Fen Chen, Yu-Jong Wu","doi":"10.1063/10.0028139","DOIUrl":"https://doi.org/10.1063/10.0028139","url":null,"abstract":"The IR and UV absorption spectra of CO2+ isolated in solid neon were studied by using our newly built mass-selective matrix isolation system. The IR absorption spectrum revealed the formation of CO2 in both cationic and anionic forms in solid Ne, since neutral CO2 was also used to serve as an electron scavenger in this study. Subsequently, we recorded the UV absorption spectrum of the same matrix sample in the spectral region 270−400 nm, encompassing the electronic transitions of CO2+ from the ground state to the first two electronic excited states. Notably, the observation of the electronic transition A2Πu←X2Πg was dominated by the vibrational progression of the symmetric CO stretching mode, while a single sharp band was observed in the electronic transition B2Σu+←X2Πg. The presented spectra might be useful for future studies on terrestrial and astrochemical conjunctions.","PeriodicalId":18077,"journal":{"name":"Low Temperature Physics","volume":"29 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142201117","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}
S. J. Riepl, S. Kossler, J. Braun, J. Minár, J. V. Barth, P. Feulner
Excited with p-polarized light, the near-edge He 1s photoemission signal from monolayers of He adsorbed on the close-packed surfaces of silver, copper, ruthenium, and platinum shows periodic splitting with photoelectron momentum. By applying a simple single scattering model, we explain this effect by zero-point motion induced variation of the photo hole’s image charge screening and interference of the photoelectron’s final state wavefunction. Relativistic one-step photoemission calculations support this interpretation. In the second part of our study, we investigate neutral double excitations of He bilayers adsorbed on platinum by monitoring the emission of He+ ions. We identify strong matrix and zero-point motion effects, namely resonances absent for isolated He, density and light polarization dependence, line broadening and a correlation of excitation and kinetic ion-energy.
在 p 偏振光的激发下，吸附在银、铜、钌和铂的紧密堆积表面上的单层 He 的近边 He 1s 光发射信号会随着光电子动量的变化而出现周期性分裂。通过应用一个简单的单散射模型，我们用零点运动引起的光洞图像电荷屏蔽变化和光电子终态波函数的干涉来解释这种效应。相对论一步光发射计算支持这一解释。在研究的第二部分，我们通过监测 He+ 离子的发射，研究了吸附在铂上的 He 双层的中性双激发。我们发现了强烈的矩阵和零点运动效应，即孤立 He 不存在的共振、密度和光偏振依赖性、线宽以及激发和离子动能的相关性。
{"title":"Helium 1s photoemission and photon stimulated desorption of He+ ions by double excitations from adsorbed helium layers: Zero-point motion and matrix effects","authors":"S. J. Riepl, S. Kossler, J. Braun, J. Minár, J. V. Barth, P. Feulner","doi":"10.1063/10.0028136","DOIUrl":"https://doi.org/10.1063/10.0028136","url":null,"abstract":"Excited with p-polarized light, the near-edge He 1s photoemission signal from monolayers of He adsorbed on the close-packed surfaces of silver, copper, ruthenium, and platinum shows periodic splitting with photoelectron momentum. By applying a simple single scattering model, we explain this effect by zero-point motion induced variation of the photo hole’s image charge screening and interference of the photoelectron’s final state wavefunction. Relativistic one-step photoemission calculations support this interpretation. In the second part of our study, we investigate neutral double excitations of He bilayers adsorbed on platinum by monitoring the emission of He+ ions. We identify strong matrix and zero-point motion effects, namely resonances absent for isolated He, density and light polarization dependence, line broadening and a correlation of excitation and kinetic ion-energy.","PeriodicalId":18077,"journal":{"name":"Low Temperature Physics","volume":"4 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142201078","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}
Characteristic features of the structure (geometries, electronic structures), vibrational spectra (infrared), and photochemistry of a series of simple hydantoins (parent hydantoin, 1-methylhydantoin, 5-methylhydantoin, and 5-acetic acid hydantoin), and effects of substituent on these properties, are reviewed in a comparative comprehensive perspective taken as a basis the low-temperature matrix isolation infrared spectroscopy and electronic structure quantum chemistry data we have reported before for the individual compounds. It is shown that the hydantoin moiety shows a general tendency towards planarity (or quasi-planarity), mostly determined by the π-electron delocalization in the system, in which the two nitrogen atoms are extensively involved and, in the molecules studied, also counts with the involvement of the π-type orbitals of the –C5H2– or –C5HR– (with R ˭ CH3 or CH2COOH in 5-methylhydantoin and 5-acetic acid hydantoin, respectively) fragment (hyperconjugation). The geometries and charge density analyses of the compounds also show that the main electronic effects in the hydantoin ring are the N-to-(C ˭ O) π-electron donation, and the σ system back-donation from the σ-lone electron pairs of the oxygen atoms to the ring. The frequencies of the bands observed in the matrix-isolation infrared spectra (Ar; 10 K) of the different compounds that are assigned to the carbonyl and amine fragments are discussed comparatively, and substituent effects are assessed. Finally, the UV-induced (λ = 320 nm) photochemistry of the hydantoins is shown to share a common pattern, leading to the concerted extrusion of isocyanic acid and carbon monoxide, accompanied by an imine derivative that depends upon the specific hydantoin reactant. An additional photofragmentation pathway, most probably involving nitrene intermediacy, also takes place for 1-methylhydantoin, indicating a specific effect of the substitution at position 1 of the hydantoin ring on the photofragmentation of hydantoins.
{"title":"Revisiting structural, vibrational, and photochemical data of matrix-isolated simple hydantoins — Common features and substituent effects","authors":"Rui Fausto, Gulce O. Ildiz, Bernardo A. Nogueira","doi":"10.1063/10.0028129","DOIUrl":"https://doi.org/10.1063/10.0028129","url":null,"abstract":"Characteristic features of the structure (geometries, electronic structures), vibrational spectra (infrared), and photochemistry of a series of simple hydantoins (parent hydantoin, 1-methylhydantoin, 5-methylhydantoin, and 5-acetic acid hydantoin), and effects of substituent on these properties, are reviewed in a comparative comprehensive perspective taken as a basis the low-temperature matrix isolation infrared spectroscopy and electronic structure quantum chemistry data we have reported before for the individual compounds. It is shown that the hydantoin moiety shows a general tendency towards planarity (or quasi-planarity), mostly determined by the π-electron delocalization in the system, in which the two nitrogen atoms are extensively involved and, in the molecules studied, also counts with the involvement of the π-type orbitals of the –C5H2– or –C5HR– (with R ˭ CH3 or CH2COOH in 5-methylhydantoin and 5-acetic acid hydantoin, respectively) fragment (hyperconjugation). The geometries and charge density analyses of the compounds also show that the main electronic effects in the hydantoin ring are the N-to-(C ˭ O) π-electron donation, and the σ system back-donation from the σ-lone electron pairs of the oxygen atoms to the ring. The frequencies of the bands observed in the matrix-isolation infrared spectra (Ar; 10 K) of the different compounds that are assigned to the carbonyl and amine fragments are discussed comparatively, and substituent effects are assessed. Finally, the UV-induced (λ = 320 nm) photochemistry of the hydantoins is shown to share a common pattern, leading to the concerted extrusion of isocyanic acid and carbon monoxide, accompanied by an imine derivative that depends upon the specific hydantoin reactant. An additional photofragmentation pathway, most probably involving nitrene intermediacy, also takes place for 1-methylhydantoin, indicating a specific effect of the substitution at position 1 of the hydantoin ring on the photofragmentation of hydantoins.","PeriodicalId":18077,"journal":{"name":"Low Temperature Physics","volume":"60 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142201076","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}
Lucas Da Silva Sa, Ander Camiruaga, Katia Le Barbu-Debus, Jordan A. Claus, Manuel Goubet, Rodolphe Pollet, Wutharath Chin
Small α-dicarbonyl compounds like succinic acid are found abundantly in the atmosphere, thereby contributing to the formation of secondary organic aerosols through solid or liquid particles and gas-phase molecular clusters. The vibrational spectrum of succinic acid was measured in two different environments to evidence the role of the medium on the geometry adopted by the acid. Different structures were observed. The planar and extended structures of succinic acid were favored in the solid state whereas the non-planar gauche conformer was the predominant form in an argon matrix at 20 K, similar to the gas phase. Aided by quantum chemistry calculations and the non-covalent interactions analysis, we investigated the conformational diversity of succinic acid to understand the factors that govern the stability of the acid.
琥珀酸等小型 α-二羰基化合物大量存在于大气中，通过固态或液态颗粒和气相分子簇促进了二次有机气溶胶的形成。我们在两种不同的环境中测量了琥珀酸的振动光谱，以证明介质对琥珀酸几何形状的影响。观察到了不同的结构。在固态下，琥珀酸的平面结构和扩展结构更受青睐，而在 20 K 的氩基质中，非平面的高切构象体则是主要形式，与气相类似。在量子化学计算和非共价相互作用分析的帮助下，我们研究了琥珀酸的构象多样性，以了解影响琥珀酸稳定性的因素。
{"title":"Unveiling the conformational diversity of succinic acid: Insights from IR spectroscopy and quantum chemical calculations","authors":"Lucas Da Silva Sa, Ander Camiruaga, Katia Le Barbu-Debus, Jordan A. Claus, Manuel Goubet, Rodolphe Pollet, Wutharath Chin","doi":"10.1063/10.0028183","DOIUrl":"https://doi.org/10.1063/10.0028183","url":null,"abstract":"Small α-dicarbonyl compounds like succinic acid are found abundantly in the atmosphere, thereby contributing to the formation of secondary organic aerosols through solid or liquid particles and gas-phase molecular clusters. The vibrational spectrum of succinic acid was measured in two different environments to evidence the role of the medium on the geometry adopted by the acid. Different structures were observed. The planar and extended structures of succinic acid were favored in the solid state whereas the non-planar gauche conformer was the predominant form in an argon matrix at 20 K, similar to the gas phase. Aided by quantum chemistry calculations and the non-covalent interactions analysis, we investigated the conformational diversity of succinic acid to understand the factors that govern the stability of the acid.","PeriodicalId":18077,"journal":{"name":"Low Temperature Physics","volume":"38 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142201081","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}
A. Iguchi, A. Hirota, S. Menk, T. Yamaguchi, H. Tanuma, J. R. Harries, S. Kuma, T. Azuma
We determined the size distribution of helium droplets produced in a pulsed beam in the condensation regime from the gas phase. Following electron-impact ionization, the mass-to-charge ratios of the positively charged droplets were determined by measuring their kinetic energies and velocities using an electrostatic cylindrical deflector setup. Over a range of different source conditions, we observed bimodal velocity distributions and log-normal size distributions. Our results are similar to those reported for continuous beams, but with mean sizes larger by a factor of around 100. The log-normal size distributions reported here differ strongly from the exponential distributions recently reported for a pulsed beam produced using a different nozzle design.
{"title":"Size distribution of helium droplets in the condensation regime of a pulsed beam","authors":"A. Iguchi, A. Hirota, S. Menk, T. Yamaguchi, H. Tanuma, J. R. Harries, S. Kuma, T. Azuma","doi":"10.1063/10.0028187","DOIUrl":"https://doi.org/10.1063/10.0028187","url":null,"abstract":"We determined the size distribution of helium droplets produced in a pulsed beam in the condensation regime from the gas phase. Following electron-impact ionization, the mass-to-charge ratios of the positively charged droplets were determined by measuring their kinetic energies and velocities using an electrostatic cylindrical deflector setup. Over a range of different source conditions, we observed bimodal velocity distributions and log-normal size distributions. Our results are similar to those reported for continuous beams, but with mean sizes larger by a factor of around 100. The log-normal size distributions reported here differ strongly from the exponential distributions recently reported for a pulsed beam produced using a different nozzle design.","PeriodicalId":18077,"journal":{"name":"Low Temperature Physics","volume":"11 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142201115","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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