Dipartimento di Chimica G. Ciamician, Università di Bologna, Via F. Selmi 2, I-40126 Bologna, Italy.
J Phys Chem A. 2011 Feb 3;115(4):453-9. doi: 10.1021/jp110510v. Epub 2010 Dec 21.
A combined microwave, infrared, and computational investigation of CHBrF(2) is reported. For the vibrational ground state, measurements in the millimeter- and sub-millimeter-wave regions for CH(79)BrF(2) and CH(81)BrF(2) provided rotational and centrifugal-distortion constants up to the sextic terms as well as the hyperfine parameters (quadrupole-coupling and spin-rotation interaction constants) of the bromine nucleus. The determination of the latter was made possible by recording of spectra at sub-Doppler resolution, achieved by means of the Lamb-dip technique, and supporting the spectra analysis by high-level quantum chemical calculations at the coupled-cluster level. In this context, the importance of relativistic effects, which are of the order of 6.5% and included in the present work using second-order direct perturbation theory, needs to be emphasized for accurate predictions of the bromine quadrupole-coupling constants. The infrared measurements focused on the ν(4) fundamental band of CH(79)BrF(2). Fourier transform investigations using a synchrotron radiation source provided the necessary resolution for the observation and analysis of the rotational structure. The spectroscopic parameters of the v(4) = 1 state were found to be close to those of the vibrational ground state, indicating that the ν(4) band is essentially unaffected by perturbations.
本文报道了 CHBrF(2) 的微波、红外和计算综合研究。对于振动基态，CH(79)BrF(2) 和 CH(81)BrF(2) 在毫米波和亚毫米波区域的测量提供了旋转和离心扭曲常数，直至六次项，以及溴核的超精细参数（四极耦合和自旋-旋转相互作用常数）。通过 Lamb-dip 技术实现的亚多普勒分辨率记录光谱，并通过耦合簇水平的高精度量子化学计算支持光谱分析，从而有可能确定后者。在这方面，需要强调相对论效应对准确预测溴核四极耦合常数的重要性，相对论效应的量级约为 6.5%，并在本工作中使用二级直接微扰理论进行了包含。红外测量集中在 CH(79)BrF(2)的ν(4)基频带。使用同步辐射源的傅里叶变换研究提供了观察和分析旋转结构所需的分辨率。v(4)=1 态的光谱参数与振动基态非常接近，表明ν(4)带基本上不受扰动影响。
