Effect of rotational excitation on the band oscillator strength of OH

Abstract

Using a continuous-wave, single-frequency, tunable dye laser, the authors have made accurate absorption measurements of the band oscillator strength for various rotational-electronic lines in the ${}_{}{}^2{}_{}{}^{}\Sigma _{}^{+}{}_{}{}^{}(v^{\prime }=0)\leftarrow {}_{}{}^2{}_{}{}^{}\Pi (v^{\prime \prime }=0)$ transitions of OH. The band oscillator strength is seen to decrease linearly with the energy of rotational excitation. It is established that this decrease results solely from lengthening of the internuclear distance due to rotation.