Flaud J, Arcas P, Lafferty WJ, Bürger H, Pawelke G
Laboratoire de Photophysique Moléculaire, CNRS, Université Paris-Sud, Bâtiment 210, Orsay Cedex, F-91405, France
J Mol Spectrosc. 2000 Oct;203(2):249-254. doi: 10.1006/jmsp.2000.8180.
Spectra of (10)B monoisotopic diborane, B(2)H(6), have been recorded at high resolution (2-3 x 10(-3) cm(-1)) by means of Fourier transform spectroscopy in the region 700-1300 cm(-1). A thorough analysis of the nu(18) a-type, nu(14) c-type, and nu(5) symmetry-forbidden band has been performed. Of particular interest are the results concerning the nu(5) symmetry-forbidden band, which is observed only because it borrows intensity through an a-type Coriolis interaction with the very strong nu(18) infrared band located approximately 350 cm(-1) higher in wavenumber. The nu(5) band has been observed around 833 cm(-1) and consists of a well-resolved Q branch accompanied by weaker P- and R-branch lines. Very anomalous line intensities are seen, with the low K(a) transitions being vanishingly weak, and Raman-like selection rules observed. The determination of the upper state Hamiltonian constants proved to be difficult since the corresponding energy levels of each of the bands are strongly perturbed by nearby dark states. To account for these strong localized resonances, it was necessary to introduce the relevant interacting terms in the Hamiltonian. As a result the upper state energy levels were calculated satisfactorily, and precise vibrational energies and rotational and coupling constants were determined. In particular the following band centers were derived: nu(0) (nu(5)) = 832.8496(70) cm(-1), nu(0) (nu(14)) = 977.57843(70) cm(-1), and nu(0) (nu(18)) = 1178.6346(40) cm(-1). (Type A standard uncertainties (1varsigma) are given in parentheses.) Copyright 2000 Academic Press.
利用傅里叶变换光谱法在700 - 1300厘米⁻¹区域以高分辨率（2 - 3×10⁻³厘米⁻¹）记录了硼 - 10单同位素乙硼烷（B₂H₆）的光谱。对ν₁₈ a型、ν₁₄ c型和ν₅对称禁戒带进行了全面分析。特别令人感兴趣的是关于ν₅对称禁戒带的结果，该禁戒带之所以被观测到，只是因为它通过与波数高约350厘米⁻¹处非常强的ν₁₈红外带的a型科里奥利相互作用借用了强度。ν₅带在833厘米⁻¹附近被观测到，由一个分辨良好的Q支以及较弱的P支和R支谱线组成。观测到非常异常的谱线强度，低K(a)跃迁极其微弱，并观测到类似拉曼的选择规则。由于每个能带的相应能级受到附近暗态的强烈扰动，确定上能级哈密顿常数被证明是困难的。为了考虑这些强局域共振，有必要在哈密顿量中引入相关的相互作用项。结果令人满意地计算出了上能级能量，并确定了精确的振动能量以及转动和耦合常数。特别得出了以下能带中心：ν₀(ν₅) = 832.8496(70)厘米⁻¹，ν₀(ν₁₄) = 977.57843(70)厘米⁻¹，ν₀(ν₁₈) = 1178.6346(40)厘米⁻¹。（括号内给出了A类标准不确定度（1σ）。）版权所有2000年，学术出版社。
