Electronic spectroscopy and photoisomerization of trans-urocanic acid in a supersonic jet.

摘要: trans-Urocanic acid (trans-UA), a component of the epidermal layer skin, exhibits wavelength-dependent photochemistry. The quantum efficiency isomerization to cis-UA is greatest when molecule excited on long wavelength tail its absorption profile in solution (300−320 nm). However, exciting where it absorbs UV light most efficiently (260−285 nm) causes almost no isomerization. We have used fluorescence excitation and dispersed emission methods supersonic jet investigate electronic states involved this complex interesting Three distinct regions are present spectrum. Region I, which below barrier, contains sharp, well-resolved peaks that upon emit from S1 state trans-UA. II increase broadness decrease intensity with increasing energy. Upon these produce dual both trans- cis-UA. trans...