ROTATIONAL CONSTANTS OF MOLECULES WITH DOUBLE-MINIMUM POTENTIALS.

Abstract

The rotational constants of molecules in successive levels of a symmetric double-minimum potential show a characteristic staggering that is fairly well represented by a term in $$, where Q is the coordinate for the double-minimum motion. A precise representation can be obtained by adding a term in $$, but the observed coefficients of $$ are much larger than expected from the expansions of the moments of inertia.$^{1}$ The present work uses a term in $$ rather than in $, P$ being the momentum conjugate to Q. This term in $$ originates from the second-order effects of Coriolis interaction with the other vibrations. For a quartic potential with a negative quadratic barrier the two alternative expressions provide identical fits to the observed constants, because the virial theorem gives a linear relation between $, $ and $$. Preliminary calculations show that the observed coefficients of $$ are of the correct order of magnitude for this Coriolis mechanism.