Direct spectral evidence of single-axis rotation and ortho-hydrogen-assisted nuclear spin conversion of CH(3)F in solid para-hydrogen

Abstract

Observation of two weak absorption lines from the E (K=1) level and one intense feature from A (K=0) for degenerate modes v(4) and v(6) of CH(3)F provides direct spectral evidence that CH(3)F isolated in p-H(2) rotates about only its symmetry axis, and not about the other two axes. An interaction between A and E vibrational levels caused by the partially hindered spinning rotation is proposed. Conversion of nuclear spin between A and E components of CH(3)F is rapid when p-H(2) contains some o-H(2), but becomes slow when the proportion of o-H(2) is much decreased. (c) 2008 American Institute of Physics.