Determination of the dipole moment of the amino radical by optical Stark spectroscopy with a tunable dye laser

Abstract

Stark effects have been observed for individual lines in the excitation spectrum of the NHD radical, recorded in the visible region with a tunable dye laser. Even though the spectra have been studied with Doppler limited linewidths, it has been possible to resolve individual MJ components. The results are interpreted in terms of an interaction between the applied electric field and the dipole moment of the molecule in the ground state (predominantly involving the a component) and yield a value for μ of 1·82±0·05 D. The experiments performed on transitions to the (0, 9, 0) level of the à 2 A′ state suggest that there is a significant contribution to the Stark effect from the molecule in the upper state also; the a component of the dipole moment involved is measured to be 0·19±0·06 D. Possible explanations of the origin of this dipole moment are discussed.