The photophysics and photochemistry of ultraviolet laser dyes.

摘要

The photophysical and photochemical properties of ultraviolet laser dyes have been investigated. Testing procedures for laser dyes have been shown to be good indicators for the practical use of new dyes. These tests include: concentration optimization, conversion efficiency determination, tuning range measurements, and half-life (photodegradation) determination.; New p-terphenyl deriviatives have been tested. Substantially greater photodegradation half-lives have been found for some alkyl substituted derivatives, up to three times greater than the parent structure.; Solvent studies using p-terphenyl (PTP) and Di-t-amyl-PTP (DTAPTP) have been done for various solvents. It was determined that p-dioxane and n-heptane were the best solvents for these dyes.; Cover gas studies were done with PTP and 4,4{dollar}sp{lcub}primeprimeprime{rcub}{dollar}-Bis-(2-butyloctyloxy)-p-quaterphenyl (BBQ) using argon, static air, circulated room air, bottled air, oxygen and nitrogen. It was determined that the photodegradation half-life of PTP depends the volume of solvent in the circulators for some solvents.; Dye mixing studies using tetra-t-butyl-p-terphenyl (TTPTP) and p-quaterphenyl (PQP) were done in p-dioxane. The tuning range increased from a FWHM of near 15nm to about 28nm. Forster energy transfer along with independent lasing were determined to the be the most likely mechanisms.; Detailed photodegradation studies of the PTP/p-dioxane system and the PTP/n-heptane system were done. Evidence of solvent interaction and the formation of solvent photo-products was discovered in the case of the PTP/p-dioxane system. These photoproducts are involved in a quenching mechanism which accounts for most of the laser gain loss in this system. The PTP/n-heptane system showed that the loss in laser gain was due mainly to loss of the dye in solution.