J. Heyrovský Institute of Physical Chemistry, vvi, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
J Phys Chem A. 2011 Feb 17;115(6):1063-8. doi: 10.1021/jp1090312. Epub 2011 Jan 26.
The parallel vibration-rotation band ν(4) of methyl isocyanide (CH(3)NC), with a band center at 944.9 cm(-1), was studied by FTIR spectroscopy between 890 and 980 cm(-1) in order to improve the ground-state rotational constants. Such improvement is essential for the scheduled studies of excited vibrational levels and their mutual anharmonic resonances occurring at higher values of the K rotational number. Ground-state combination differences generated from this band, spanning values of J/K from 0 to 85/13, were combined with rotational data from the literature and newly measured rotational transitions, extending the J/K range from 3/0 up to 31/14, and fitted simultaneously with a fully quantitative reproduction of the data. The infrared data of the ν(4) band were analyzed together with rotational data of the ν(4) = 1 level, spanning values of J/K from 4/0 to 14/12. The fit in the approximation of an isolated vibrational state, with the transitions perturbed by weak local resonances excluded, yields reproduction of the data within experimental uncertainties.
研究了甲基异氰酸酯（CH(3)NC）的ν(4)平行振动-转动带，其带心位于 944.9 cm(-1)，在 890 到 980 cm(-1)之间通过傅里叶变换红外光谱进行研究，目的是改进基态转动常数。这种改进对于计划研究更高 K 转动数的激发振动能级及其相互非谐共振至关重要。从这个带产生的基态组合差跨越 J/K 值为 0 到 85/13，与文献中的转动数据和新测量的转动跃迁相结合，将 J/K 范围从 3/0 扩展到 31/14，并同时进行拟合，以完全定量再现数据。ν(4)带的红外数据与ν(4) = 1 能级的转动数据一起进行分析，跨越 J/K 值为 4/0 到 14/12。在排除弱局部共振影响的孤立振动态近似下进行拟合，在实验不确定性范围内再现数据。
