Study of transient absorption and emission spectra of reaction Intermediates using the stretched polymer film method.

点击翻译按钮获取中文摘要

Polarized transient absorption spectra of benzophenone and its methoxyl derivatives were studied by use of the stretched polymer film technique combined with nano-second laser flash photolysis. To estimate reliability of the data obtained by our system constructed, polarized triplet-triplet absorption spectrum of anthracene were measured in the stretched poly(vinyl alcohol) [PVA] film and analyzed. The results are consistent with those obtained by using the mixed crystal, and it is confirmed that our system is available for measurements of polarized transient spectra. Polarized triplet-triplet absorption spectra of benzophenone and its methoxyl derivatives were measured at 20-40ns after the laser flash in the stretched PVA film. Direction of transition moment of each absorption band was determined. Spectral change induced by introduction of methoxyl group(s) was analyzed. It was made clear that absorption band with short-axis polarization appeared around 450nm, and one with long-axis polarization was observed longer than 650nm. By measuring transient spectra of benzophenone at 400 ns after the 266nm laser flash, polarized absorption spectra of benzophenone ketyl radicals were determined in the stretched PVA film. Analytical results were consistent with those obtained for ketyl radicals produced in PVA film by gamma-irradiation. A part of these results was presented in the 14-th IUPAC symposium on Photochemistry held in Leuven, Belgium.