Thef-sum rule for “rotator strengths”

Abstract

The concept of oscillator strengthsf for the emission and absorption of radiation by the electrons of an atomic system which has lead to the familiar Kuhn-Thomas-Reichef-sum rule has been extended to that of “rotator strengths” for a molecule approximated by a freely rotating rigid asymmetric rotator with a permanent body fixed dipole moment. As a consequence of the different type of physical system the resulting “f-sum rule for rotator strengths” holds only for what may be termed average rotator strengths (averaged over theM-degenerate sublevels).