C60Cl24 molecule in crystalline toluene matrix

摘要

The absorption spectra of the motecules C60C24, embedded in a solid matrix of toluene, C6H5(CH3), consist of three groups of lines, A, B, and C, situated at 1.6-1.8, 2.3-2.5, and 2.6-2.8 eV. We assign the groups of lines to purely electronic and electron-vibrational (vibronic) transitions S-o --> S-n in C60Cl24 molecules in different positions with respect to the crystalline matrix (Shpol'skii effect). The molecules C60Cl24 are known to have three isomers: a T-h-symmetric and two D-2h-symmetric (1 and 2). The D-2h-symmetric isomer 1 has the most appropriate value of the first electronic transition and is probably responsible for the observed absorption spectra. We report the results of calculations made to find the most appropriate cavities in a toluene crystal and the most advantageous positions of D-2h-symmetric isomers 1 of the C60Cl24 molecule in these cavities. The most appropriate three cavities in the toluene crystal for the D-2h- symmetric isomers 1 of the C60Cl24 molecule are found to be centered in the inversion center r(c) = 0.5 a (a, b, c being primitive translation vectors) and formed by moving away 14 somewhat different toluene molecules. The very fact that there exists a relatively small number of energetically preferred ways to embed the molecule C60Cl(24) in the crystal matrix of toluene is encouraging and correlates with the small number of Shpol'skii lines in the spectra of pure electronic transitions in the system under consideration. Taking into account toluene molecule relaxation around the embedded molecule C60Cl24 will permit a closer comparison of the theoretical and experimental results. (C) 2004 Wiley Periodicals, Inc.