title: Microwave Spectroscopy of the Ground, nu18, 2nu18, and nu11 Vibrational States of CF3CFH2.
abstract: The rotational spectra of the ground, nu18, 2nu18, and nu11 vibrational states of CF3CFH2 have been investigated in the frequency range 48-116 GHz with an accuracy of measurement better than 10 kHz. Rotational and centrifugal distortion parameters derived using an S-reduced Watson-type Hamiltonian have been improved for the ground and nu18 states. An interaction between 2nu18 and nu11 vibrational states has been detected, and rotational, centrifugal distortion, and coupling parameters of these states have been determined for the first time. The wavenumber difference between the 2nu18 and nu11 states was found to be 11.20996(54) cm-1. Copyright 1999 Academic Press.