http://worldcat.org/entity/work/id/137233754

Nanosecond and Picosecond Spectroscopy and Kinetics of Dynamic Absorbing Materials

There is an increasing need to provide protection for both personnel and electronic sensors against laser radiation in the visible and near infra-red regions. The proliferation of laser frequencies and the advent of tunable lasers combine to create a threat that static filters alone cannot combat. Dynamic filters that become highly absorbing only on exposure to the incident laser radiation would provide an attractive solution, especially if the dynamic absorption could be made to develop very rapidly and also be rapidly reversible after the laser pulse is over. This report describes research aimed at the further development of ultra-fast spectroscopic instrumentation constructed in the author's laboratory and its application to studying several phenomena capable of giving rise to dynamic absorption in selected classes of chemical compounds. These phenomena include the direct photoproduction on the picosecond time scale of absorbing transient species such as excited singlet states and excited triplet states of conjugated organic molecules and dyes, the production of radical ions of similar compounds via photoexcitation followed by fast electron transfer and the production of various excited states of inorganic complexes. A low-cost automated, picosecond laser spectrometer based on a two-dimensional optical multichannel analyzer (OMA) interfaced to a home assembled microcomputer has been developed.

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