Batonneau-Gener, I; Moissette, A; Brémard, C; Buntinx, G
Abstract: Transient diffuse reflectance UV–vis absorption (TDRUV) and time resolved resonance Raman (TR3) spectroscopy (370nm exciting laser line, 8ns) were performed to investigate the species generated by UV pulsed laser photolysis (248nm, 20ns) of biphenyl (BP) occluded in cavities of dehydrated silica-rich Y-faujasitic (M n FAU) zeolites with M n (AlO2) n (SiO2)192−n formulae per unit cell. The TDRUV spectra were recorded in the time range 0.5–340μs and the TR3 spectra were recorded in the 0.05–100μs as functions of aluminum content (n =0, 56), extra framework cations (M=Na+, K+, Cs+), BP loading (1, 2, 4, 8, 16BP/UC) and laser energy (0.15–1.5mJ). Specific spectra of BP(T1) triplet state, BP + radical cation, trapped electron as Na4 3+ cluster and BP − radical anion were resolved by Multivariate curve resolution (MCR) of TDRUV and TR3 data sets. The RR spectra of BP + and BP(T1) correspond to nearly planar structures. The concentration decays fit a model of dispersed heterogeneous kinetics. At lower laser energy, BP(T1) was generated as major transient species. The energy transfer via T1 occurs with rates not greater than 10−6 s−1. Photoionization is found to be the dominant phenomenon at higher pump laser energy. BP +, Na4 3+ and BP − exhibit distinct decay behaviors with rates not lower than 10−3 s−1. In polar environment of Na56FAU supercage, the ejected electron is trapped as Na4 3+ cluster at low loading and as BP − at high loading. In the non-polar environment of FAU supercage, the ejected electron ... [Copyright 2008 Elsevier] Copyright of Journal of Photochemistry & Photobiology A: Chemistry is the property of Elsevier Science Publishers B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)