A sensitive dye-laser spectrometer is constructed to observe the Stark effect of weak-overtone transitions in NH3. A ΔP/P sensitivity of 10-6 is achieved with the help of a laser-noise-reduction system. A relatively short (30-cm) and narrow-gap (0.25-mm) Stark electrode makes it possible to apply a high electric field on molecular gas at low pressure (~1 Torr). The Stark components of the υ = 5 overtone band transitions of NH3 are well resolved. The rotational assignments are confirmed, and the dipole moment in the υ = 5 excited vibrational state is determined to be 1.40 ± 0.02 D.
© 1989 Optical Society of America
Ken’ichi Nakagawa, Yoshiki Moriwaki, and Tadao Shimizu, "Observation of the Stark effect in high-overtone band transitions of NH3," Opt. Lett. 14, 488-490 (1989)