LASER-INDUCED FLUORESCENCE OF DECAMETHYLRHENOCENE IN LOW-TEMPERATURE MATRICES

The emission and excitation spectra of decamethylrhenocene, Re(pi(5)-C (5)Me(5))(2) have been recorded in argon and in nitrogen matrices with a tunable pulsed laser as exciting source. In argon matrices two sets of spectra may be excited selectively corresponding to different trap ping sites or conformers of the guest molecules. Each set is dominated by a progression in vs, a vibration corresponding to the in-phase com bination of ring-metal-ring and ring-methyl bending modes (nu(8)' = 39 2 (2) cm(-1) nu(8) '' = 383 (1) cm(-1)). Much weaker features can be d etected corresponding to progressions involving the three other totall y symmetric modes (nu(x) + n nu 8, x = 6, 7, 9, n = 0, 1, 2,...). The emission and excitation bands in the principal site are symmetrical in shape with full width at half-maximum of only ca. 6 cm(-1). The spect ra of Re(eta(5)-C(5)Me(5))(2) in nitrogen matrices are similar to thos e in argon matrices, but differ in site/conformer structure. The excit ed state lifetime in nitrogen matrices has been determined by single p hoton counting methods to be 3.69 (7) ns, The quantum yield for emissi on in nitrogen matrices is estimated as 0.010.