Department of Chemistry, Faculty of Sciences, Okayama University, Tsushima-naka 3-1-1, Okayama, 700-8530, Japan.
J Phys Chem A. 2011 Aug 4;115(30):8458-63. doi: 10.1021/jp204068w. Epub 2011 Jul 8.
The gas-phase high-resolution absorption spectrum of the ν(6) band of cyclopropenylidene (c-C(3)H(2)) has been observed using a Fourier transform infrared spectrometer for the first time. The molecule has been produced by microwave discharge in an allene (3.3 Pa) and Ar (4.0 Pa) mixture inside a side arm glass tube. The observed spectrum shows a pattern of c-type ro-vibrational transitions in which the Q-branch lines strongly and distinctly stand out in the spectrum. A combined least-squares analysis of the observed 216 ro-vibrational transitions together with 28 millimeter-wave rotational transitions from the previous study has resulted in an accurate determination of the molecular constants in the ν(6) state. The band center is found to be at 776.11622(13) cm(-1) with one standard deviation in parentheses, which is 2.3% lower than the matrix isolation value. The intensity ratio I(3)(ν(3))/I(6)(ν(6)) obtained from the observed ν(3) and ν(6) bands, 1.90(9), is somewhat lower than the ratio estimated from ab initio (2.4-2.6) and DFT (2.8) calculations.
环丙烯烯（c-C3H2）ν(6)带的气相高分辨率吸收光谱首次使用傅里叶变换红外光谱仪进行了观察。该分子是在侧臂玻璃管内的丙烯（3.3 Pa）和 Ar（4.0 Pa）混合物中通过微波放电产生的。观察到的光谱显示出 c 型振转跃迁的模式，其中 Q 支谱线在光谱中强烈而明显地突出。对观察到的 216 个振转跃迁与先前研究中的 28 个毫米波转动跃迁进行的联合最小二乘分析，导致对 ν(6)态的分子常数进行了准确确定。带中心位于 776.11622(13)cm-1，括号内为一个标准偏差，比基质隔离值低 2.3%。从观察到的 ν(3)和 ν(6)带获得的强度比 I(3)(ν(3))/I(6)(ν(6))为 1.90(9)，略低于从头算（2.4-2.6）和 DFT（2.8）计算估计的值。
