Two-Photon Coherent-Transient Measurement of the Nonradiative Collisionless Dephasing Rate in SF6via Doppler-Free Degenerate Four-Wave Mixing

This Letter reports, for the first time, an experimental measurement of the collision-less dephasing time of the ${\nu }_3=2\mathrm{}$ level in S${\mathrm{F}}_6$ using Doppler-free two-photon degenerate four-wave mixing. The measurement is performed in the time domain by use of a short-pulse C${\mathrm{O}}_2$ laser to establish a molecular two-photon coherent state. The coherent state is then probed as a function of time to yield a dephasing time of 1.8 nsec which is related to intramolecular dephasing rates.