Ulenikov O N, Bekhtereva E S, Albert S, Bauerecker S, Niederer H M, Quack M
Physical Chemistry, ETH Zürich, CH-8093 Zürich, Switzerland.
J Chem Phys. 2014 Dec 21;141(23):234302. doi: 10.1063/1.4899263.
We have recorded the complete infrared spectrum of methane (12)CH4 and its second most abundant isotopomer (13)CH4 extending from the fundamental range starting at 1000 cm(-1) up to the overtone region near 12,000 cm(-1) in the near infrared at the limit towards the visible range, at temperatures of about 80 K and also at 298 K with Doppler limited resolution in the gas phase by means of interferometric Fourier transform spectroscopy using the Bruker IFS 125 HR prototype (ZP 2001) of the ETH Zürich laboratory. This provides the so far most complete data set on methane spectra in this range at high resolution. In the present work we report in particular those results, where the partial rovibrational analysis allows for the direct assignment of pure (J = 0) vibrational levels including high excitation. These results substantially extend the accurate knowledge of vibrational band centers to higher energies and provide a benchmark for both the comparison with theoretical results on the one hand and atmospheric spectroscopy on the other hand. We also present a simple effective Hamiltonian analysis, which is discussed in terms of vibrational level assignments and (13)C isotope effects.
我们利用苏黎世联邦理工学院实验室的布鲁克IFS 125 HR原型（ZP 2001），通过干涉式傅里叶变换光谱法，在气相中于约80 K以及298 K的温度下，以接近可见范围极限的近红外波段，记录了甲烷（¹²）CH₄及其第二丰富的同位素异构体（¹³）CH₄从1000 cm⁻¹起始的基频范围到近12,000 cm⁻¹的泛音区域的完整红外光谱，分辨率受多普勒限制。这提供了该范围内迄今为止分辨率最高的关于甲烷光谱的最完整数据集。在本工作中，我们特别报告了那些部分振转分析允许直接指定包括高激发态的纯（J = 0）振动态的结果。这些结果极大地扩展了对振动带中心到更高能量的准确认识，并为一方面与理论结果比较以及另一方面与大气光谱学比较提供了一个基准。我们还提出了一种简单的有效哈密顿分析，并根据振动态指定和¹³C同位素效应进行了讨论。
