FURTHER ANALYSIS OF VINYL IODIDE MICROWAVE SPECTRUM

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 A, the inertial defect. This value of A agrees with one computed from the infrared spectrum by the approximate method of Herschbach and Laurie. The rotational constants are, neglecting centrifugal-distortion effects, 4=53.3±0.4×104 MHz, 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 χαα= -1654.3Ü 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.