Time-Resolved Resonance Raman Study of Biphenyl Occluded in the Supercages of Faujasitic Zeolites

Abstract

The laser photolysis (248 nm, 20 ns) of biphenyl (BP, S₀) occluded in the void space of faujasitic zeolites (NanFAU) , Nan(SiO2)192−n(AlO2)n with n=0, 56, 85 has been studied by time-resolved resonance Raman spectroscopy combined with time-resolved diffuse reflectance UV-visible absorption spectroscopy in the ns–μs time scale. The excitation (370 nm, 8 ns) of the RR scattering in the wavelength region of the UV electronic absorption of the transient species provides clear evidence of the radical cation (BP⁺) as major species for zeolites NanFAU (n=56, 85). The amount of triplet state (BP, T₁) depends on the aluminum content and in a less extent on the fluence of the pump laser at the sample.