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The pure rotational Raman spectrum of cyclopentane-d0 and cyclopentane-d10

1963; Elsevier BV; Volume: 10; Issue: 1-6 Linguagem: Inglês

10.1016/0022-2852(63)90184-x

1096-083X

Kurt Tanner, A. Weber,

Spectroscopy and Laser Applications

The pure rotational Raman spectra of C5H10 and C5D10 were photographed under high dispersion in the 13th order of a 300 grooves/mm plane grating using the line Hg 4358 Å for excitation. The spectra are quite weak and diffuse and resemble that of a symmetric top rotator. The line spacing in the S branches is nearly constant with a value of about 0.864 cm−1 (C5H10) and 0.644 cm−1 (C5D10). Transitions with J up to 67 in the ordinary and up to 76 in the deuterated compound were observed in the S-branch. A number of R-branch lines were also observed. The analysis of the spectra is based upon the symmetric rotor theory and yields the following ground-state constants: C5H10 : B0 = 0.21605 ± 0.0010 cm−1,D = (5.0 ± 1.4) × 10−8 cm−1; C5D10 : B0 = 0.16102 ± 0.00012 cm−1,Dj = (4.0 ± 2.2) × 10−8 cm−1; If a planar model is assumed for the carbon ring (D5h point group) the length of the CC bond is computed to be rCC = 1.5370 ± 0.0024 Å. The cyclopentane molecule is not, however, a strict symmetric top as is known from the careful analysis of the thermodynamic functions and the vibrational spectrum. The present study does not admit any choice between the permissible C2, CS, and C1 symmetries.