Electronic relaxation of aniline in argon matrix:: A site selective laser spectroscopy

Absorption (S-1<--S-0), fluorescence (S-1-->S-0) and phosphorescence (T-1-->S-0) spectra of aniline isolated in argon matrices are presented and analyzed. Upon selective laser excitation, two families of sites are characterized by electronic spectroscopy and excited state dynamics. A strong electron/phonon coupling is observed in the S-1<->S-0 transition due to a geometry change of the molecule. Phosphorescence spectra exhibit different vibronic intensity distribution for both sites; a(1) in plane and b(1) out-of-plane modes are observed. A direct estimation of the inversion splitting in the ground state (46 cm(-1)) is obtained from the presence of an intense doublet assigned to (3)A(1)(0(+))-->(1)A(1)(0(+),0(-)) vibronic transitions. (C) 2002 American Institute of Physics.