High-resolution rovibrational spectroscopy of trans-formic acid in the v1 OH stretching fundamental: Dark state coupling and evidence for charge delocalization dynamics
High-resolution rovibrational spectroscopy of trans-formic acid in the v1 OH stretching fundamental: Dark state coupling and evidence for charge delocalization dynamics
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v1 OH 拉伸基础中反式甲酸的高分辨率振动光谱：暗态耦合和电荷离域动力学的证据
DOI：
10.1016/j.jms.2023.111743
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发表时间：
2023
影响因子：
1.4
通讯作者：
Nesbitt, David J.
中科院分区：
文献类型：
--
作者：
Chan, Ya-Chu;Nesbitt, David J.
本文首次报道了反式甲酸/Ar混合气体经狭缝喷流源超声膨胀并旋转冷却至Trot = 10.9（5）K后，在v1 OH伸缩基区的高分辨红外（IR）约化多普勒吸收谱，并用高分辨差频红外吸收谱记录了吸收信号。观察到两个强度相当的oa/b型振转带，一个10倍的weakerb型带和一个16倍的weakera型带，振动带的起源分别为3570.493（5），3566.793（5），3560.032（9）和3534.6869（2）cm−1。在Nejad和Sibert [A. Nejad，E.L. Sibert III，反式甲酸及其氘代同位素的拉曼喷射光谱：结合理论和实验以扩展振动数据库，J. Chem. Phys. 154（6）（2021）064301.]，这四个振转带分别归属于V1、（V2+V7）、（V6+ 2 V7 + 2 V9）和2 V3。具体地说，三个上面的暗态中的两个（2171（a′）和617292（a′））足够接近“亮”11（a′）态，以促进强的非谐共振相互作用，这导致强度混合到两个零级带中，否则它们将是“暗”的。此外，我们的高分辨率光谱分析表明，在这些零阶11和2171态之间存在局部旋转交叉，导致额外的谱线（即，名义上V1频带中的某些较高的电平具有多数零阶2171状态字符）。这激发了3耦合态（11，2171和617292）图像的发展，以帮助光谱分析，这能够匹配所有3个观察到的带源和相对带强度，以及指示多态（> 2）耦合的必要性。尽管受到JandKalevels（J '≤ 9和Ka' ≤ 3）在超音速射流温度下的分布范围的限制，这项工作提供了反式甲酸在v1 OH伸缩区的第一个精确光谱分析，这将有助于更完整但高度拥挤的室温FTIR光谱的归属[D. F·赫特曼斯Herregodts，M.赫尔曼，J. Campargue，A. Garnache，A. Kachanov，Spectroscopic and ab initio investigation of the ν OH overtone excitation intrans-formic acid，J. Chem. Phys. 113（4）（2000）1535-1545.].最后，与三个主要的b型带的光谱复杂性形成鲜明对比的是，在3534.6869（2）cm− 1处的lonea型2 v3振转带可以用一个简单的、严格的非对称顶部哈密顿量很好地描述。
High-resolution infrared (IR) reduced-Doppler absorption spectra of jet-cooled gas phasetrans-formic acid in thev1OH stretching fundamental region are reported for the first time, obtained by supersonically expandingtrans-formic acid/Ar mixtures through a slit jet nozzle source and rotationally cooling to Trot≈ 10.9(5) K, with absorption signals recorded by high-resolution difference-frequency IR absorption spectroscopy. Twoa/b-type rovibrational bands of comparable intensity, one ∼10-fold weakerb-type band, and one ∼6-fold weakera-type band are observed, with vibrational band origins at 3570.493(5), 3566.793(5), 3560.032(9), and 3534.6869(2) cm−1, respectively. Based on previous Raman jet spectroscopic work by Nejad and Sibert [A. Nejad, E.L. Sibert III, The Raman jet spectrum oftrans-formic acid and its deuterated isotopologs: Combining theory and experiment to extend the vibrational database, J. Chem. Phys. 154(6) (2021) 064301.], these four rovibrational bands have been assigned tov1, (v2+v7), (v6+ 2v7+ 2v9), and 2v3, respectively. Specifically, two of the three upper dark states (2171(a′) and 617292(a′)) are close enough to the “bright” 11(a′) state to facilitate strong anharmonic resonance interactions, which results in intensity mixing into the two zero-order bands that would otherwise be “dark”. Furthermore, our high-resolution spectral analysis reveals that there are local rotational crossings between these zero-order 11and 2171states resulting in extra lines (i.e., some upper levels in the nominallyv1band have majority zero-order 2171state character). This motivates development of a 3 coupled state (11, 2171, and 617292) picture to aid in the spectral analysis, which is able to match all 3 observed band origins and relative band intensities, as well as indicate the necessity of multistate (> 2) coupling. Though limited by range ofJandKalevels (J'≤ 9 andKa'≤ 3) populated at supersonic jet temperatures, this work offers first precision spectroscopic analysis oftrans-formic acid in thev1OH stretch region, which should aid in assignment of the more complete yet highly congested room temperature FTIR spectra [D. Hurtmans, F. Herregodts, M. Herman, J. Liévin, A. Campargue, A. Garnache, A. Kachanov, Spectroscopic and ab initio investigation of the νOHovertone excitation intrans-formic acid, J. Chem. Phys. 113(4) (2000) 1535–1545.]. Finally, and in sharp contrast to the spectral complexity in the three predominantlyb-type bands, the lonea-type 2v3rovibrational band at 3534.6869(2) cm−1is well described by a simple, rigid asymmetric top Hamiltonian.
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DOI：
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发表时间：
1979
期刊：
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--
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影响因子：
8.4
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影响因子：
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使用稳定的可调谐差频激光系统的高分辨率甲烷ν 3 带光谱*
DOI：
--
发表时间：
1976
期刊：
影响因子：
--
作者：
A. Pine
通讯作者：
A. Pine
甲酸 ν3 波段的亚多普勒激光 Stark 和高分辨率傅里叶变换光谱
DOI：
--
发表时间：
1987
期刊：
影响因子：
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作者：
W. Weber;P. Maker;J. Johns;E. Weinberger
通讯作者：
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