Transient frequency-modulated spectroscopy: application to the measurement of vector and scalar correlations in molecular photodissociation

摘要

Abstract: An intrinsically time-resolved version of frequency-modulation (FM) spectroscopy has been recentlydeveloped and applied to the study of gas-phasephotodissociation dynamics. Transient FM spectroscopyallows low background detection of radical species withshot-noise limited sensitivities, time resolutionsufficient for detection of collision-lessphotoproducts, and frequency resolution characteristicsof single-mode cw lasers. Methods for the quantitativeanalysis of Doppler-broadened FM line shapes to givevelocity and rotational polarization information havebeen established permitting the measurement of scalarand vector properties of molecular fragmentation inexquisite detail. Several recent examples of theapplication of transient FM spectroscopy will bepresented and discussed, including correlated scalardistributions in the dissociation of ketene fromCH$-2$/ Doppler profiles, and the full vectorcorrelation analysis of CN fragments arising from ICNdissociation. !20