Resonance Raman study of the A-band short-time photodissociation dynamics of 2,5-di-iodothiophene

J Chem Phys. 2008 Dec 7;129(21):214506. doi: 10.1063/1.3026585.

Abstract

Resonance Raman spectra were obtained for 2,5-di-iodothiophene in cyclohexane solution with excitation wavelengths in resonance with its A-band absorption. These spectra indicate that the Franck-Condon region photodissociation dynamics have multidimensional character with motion mostly along the nominal symmetric C(2)C(3)C(4)C(5) stretch nu(2) (1388 cm(-1)) of the thienyl ring and this is accompanied by motions along the nominal symmetric CSC stretch nu(6) (640 cm(-1)), the nominal symmetric C[Single Bond]I stretch nu(7) (187 cm(-1)), the nominal antisymmetric CSC stretch nu(19) (728 cm(-1)), the nominal antisymmetric C(2)C(3)C(4)C(5) stretch nu(16) (1497 cm(-1)), the nominal C(3)C(4) stretch nu(3) (1286 cm(-1)) and four other vibrational modes. A preliminary resonance Raman intensity analysis was done and the results for 2,5-di-iodothiophene were compared to previous results for 2-iodothiophene and di-iodomethane to discuss the mechanism of the symmetric breaking in the initial A-band photodissociation dynamics of 2,5-di-iodothiophene and 2-iodothiophene.