Barclay A J, McKellar A R W, Moazzen-Ahmadi N
Department of Physics and Astronomy, University of Calgary, 2500 University Drive North West, Calgary, Alberta T2N 1N4, Canada.
National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada.
J Phys Chem A. 2024 Sep 12;128(36):7628-7633. doi: 10.1021/acs.jpca.4c04599. Epub 2024 Aug 28.
Infrared spectra of acetylene-water complexes are studied in the regions of the HO ν bend (1600 cm) and the DO ν/ν stretches (2670-2808 cm), using tunable infrared sources to probe a pulsed supersonic slit jet expansion. In the HO bend region, there is a puzzling absence of = 0 transitions for CH-HO, while both = 0 and 1 are observed for CD-HO. This continues a pattern of "missing" states noted in previous infrared studies of acetylene-water. Noticeable line broadening gives estimates of upper state predissociation lifetimes of about 1.6 ns for CD-HO with = 1, 0.8 ns for CH-HO with = 1, and 0.8 ns for CD-HO with = 0. The lifetime for CH-HO = 0 must be much shorter (<0.05 ns) since rapid predissociation seems to be the only explanation for its absence in the spectrum. In the DO ν region, clear sub-bands with = 0 ← 1, 1 ← 0, and 2 ← 1 are observed which enable a good determination of the rotational constant of CH-DO (7.313 ± 0.007 cm), a first for acetylene-water dimer and larger than previously expected.
利用可调谐红外光源探测脉冲超声速狭缝射流膨胀，研究了乙炔 - 水络合物在HO ν弯曲（1600 cm）和DO ν/ν伸缩（2670 - 2808 cm）区域的红外光谱。在HO弯曲区域，对于CH - HO，令人费解的是不存在J = 0跃迁，而对于CD - HO，J = 0和J = 1跃迁均被观测到。这延续了先前乙炔 - 水红外研究中所指出的“缺失”J态的模式。明显的谱线展宽给出了对于J = 1的CD - HO，其激发态预解离寿命约为1.6 ns，对于J = 1的CH - HO为0.8 ns，对于J = 0的CD - HO为0.8 ns的估计值。由于快速预解离似乎是其在光谱中缺失的唯一解释，所以CH - HO J = 0的寿命必定短得多（<0.05 ns）。在DO ν区域，观测到了清晰的J = 0 ← 1、J = 1 ← 0和J = 2 ← 1子带，这使得能够很好地确定CH - DO的转动常数（7.313 ± 0.007 cm），这对于乙炔 - 水二聚体来说是首次，且比先前预期的要大。
