ABSORPTION SPECTRA OF ETHYLENE AND ETHYLENE-<i>d</i>₄ IN THE VACUUM ULTRAVIOLET. II

Abstract

The absorption spectra of ethylene and ethylene-d 4 have been investigated in the 1300 Å to 1500 Å region using the first order of a 21-ft. vacuum grating spectrograph. Vibrational constants for the v 2 (a g ) stretching vibration and the v 4 (a u ) twisting vibration have been determined for each of the observed five Rydberg states. The torsional oscillator–rotator treatment has been applied to the observed twisting data, and potential barriers hindering free rotation of 500 to 1200 cm −1 were obtained. It is concluded that the stable equilibrium configuration of the Rydberg states is not of D 2h symmetry but is probably bent or staggered.