An electro-optic modulator, driven at a single radio frequency ν, is used to create sidebands (νL±ν) on the frequency νL of a cw single-mode CO2 laser. Laser-induced line narrowing in molecular Stark spectroscopy is demonstrated, using double resonances of the copropagating waves at νL and (νL±ν) with pairs of coupled Doppler-broadened transitions. Doppler-free Stark spectra of the molecules PH3, 13CH3F, and 12CH3F are used to illustrate the technique. For PH3 it is found that the electric dipole moment vibrational difference ∥μ (v2=1)-μ (v=0) ∥≤0.005 D.
|Number of pages||3|
|Journal||Applied Physics Letters|
|Publication status||Published - 1977|