Time-resolved transition state spectroscopy

Abstract

The authors report the development and characterization of an apparatus capable of simultaneously generating intense femtosecond UV (308-, 248.5-nm) excitation pulses and femtosecond continua for probing photoexcited molecules by means of broadband absorption spectroscopy. The excitation pulses are obtained by amplification of femtosecond pulses in XeCl and KrF excimer gain modules. The probe pulses rely on continuum generation in the gas phase. Currently, three spectral regions can conveniently be probed; these occur in the UV (230-450 nm), visible (400-800 nm), and IR (2.2-2.7 μm). The authors describe the results of an experiment probing the formation of Tl atoms resulting from 160-fs UV photolysis of TlCl and TlI vapors.