Doppler-free spectroscopy of the ν2 band in 14NH3: Application to 16-μm generation

Abstract
Several two‐photon transitions leading to various (J,K) rotational sublevels of the ν2=2 state in 14NH3 have been observed using the high‐resolution technique of Doppler‐free two‐photon spectroscopy. It is shown that these transitions can be both tuned into resonance with the optical Stark effect and saturated with intensities of order 1–10 MW/cm2, so that laser action on many wavelengths in the vicinity of 16 μm is obtainable. This method of excitation is generally applicable for the excitation of molecular systems in frequency‐conversion processes.