Abstract

In recent papers we have described apparatus capable of simultaneously generating both intense subpicosecond UV (308-248.5-nm) excitation pulses and subpicosecond continua for probing photoexcited molecules via broadband absorption spectroscopy. Both UV (450-230-nm) and IR (2.2-2.7-μm) continua have thus far been produced through the focusing of 160-fs, 308-nm pulses into various gaseous media. A method of upconverting the IR continuum to the visible for ease of detection has also been demonstrated. We first describe these developments and then discuss the results of a time-resolved experiment using some of this new apparatus. This particular experiment combines subpicosecond 248.5-nm excitation with subpjcosecond IR continuum probing to measure the $\tilde{B}\to \tilde{A}$ internal conversion rate in 1,4-diazabicyclo[2.2.2]octane (DABCO) vapor.

© 1987 Optical Society of America