15min:

YUAN-PERN LEE AND CHUNG-WEI HUANG, Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan; KEEVIN DIDRICHE AND MICHEL HERMAN, Laboratoire de Chimie quantique et Photophysique, CP160/09, Université libre de Bruxelles, Ave. Roosevelt, 50, B-1050, Brussels, Belgium; MAUD ROTGER, Institut Carnot de Bourgogne, UMR 5209 CNRS-Université de Bourgogne, 9 avenue Alain Savary, B.P. 47870, F-21078 Dijon Cedex, France.

Spectra of C₂H₄ isolated in para-H₂ are compared with those of jet-cooled C₂H₄ recorded with an FTIR spectrometer. The ₇, ₉, and ₁₁ bands of jet-cooled C₂H₄ all exhibit an intensity distribution corresponding to about 10 K for rotation, with no evidence of nuclear spin conversion. Spectra of the ₁₁ band of C₂H₄ isolated in solid para-H₂ clearly show a rotational structure similar to that observed for C₂H₄ in helium droplets. Other bands of C₂H₄ exhibit only partially resolved rotational structures. Rotational constants B and C for ₁₁ of C₂H₄ in para-H₂ are about 50 % those of the gaseous C₂H₄. The out-of-plane deformation mode ₇ shows a small (< 1 cm^-1) blue matrix shift, whereas other modes are red-shifted by 2.2 to 3.9 cm^-1.