Further Analysis of the Vinyl Iodide Microwave Spectrum

Abstract

Reanalysis of the published vinyl iodide microwave spectrum produced refined values of previously measured constants, and determined two quantities hitherto not known with precision: χab, the off-diagonal quadrupole coupling constant, and Δ, the interial defect. This value of Δ agrees with one computed from the infrared spectrum by the approximate method of Herschbach and Laurie. The rotational constants are, neglecting centrifugal-distortion effects, A = 53.3 ± 0.4 × 104MHz, B = 3258.72 ± 0.03 MHz, C = 3066.66 ± 0.03 MHz, and Δ = 0.24 ± 0.08 amu·Å2. The quadrupole coupling constants are χaa = − 1654.3 ± 1 MHz, χbb = 768.8 ± 1 MHz, χab = −710 ± 25 MHz. Diagonalization of the χ tensor gives χαα = − 1847 MHz and χββ = 962 MHz. The angle between the a axis and the C–I bond is 15.2° ± 0.7°, assuming the χ tensor diagonal along the C–I bond.