Acta Phys. -Chim. Sin. ›› 2014, Vol. 30 ›› Issue (12): 2216-2223.doi: 10.3866/PKU.WHXB201410221


Excited State Structural Dynamics of A-Band of 4-Nitroimidazole

LI Dan, XUE Jia-Dan, ZHENG Xu-Ming   

  1. Department of Chemistry, and Key Laboratory of Advanced Textiles Materials and Manufacture Technology of the Ministry of Education, and Engineering Research Center for Eco-Dyeing and Finishing of Textiles of the Ministry of Education, Zhejiang Sci-Tech University, Hangzhou 310018, P. R. China
  • Received:2014-09-12 Revised:2014-10-22 Published:2014-11-27
  • Contact: ZHENG Xu-Ming
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21033002, 21202032) and National Key Basic Research Program of China (973) (2013CB834604).


The A-band structural dynamics of 4-nitroimidazole (4NI) were studied using resonance Raman spectroscopy and quantum mechanical calculations, and the vibrational spectra, UV absorption spectra, fluorescence spectra, and A-band resonance Raman spectra were assigned. The resonance Raman spectra of 4-nitroimidazole were obtained in methanol with excitation wavelengths in resonance with the first intense absorption band, to probe the short-time structural dynamics. The optimized geometric structures and the excitation energies of the singlet excited states S1(nOπ*) and S2(ππ*), and the conical intersection point S1(nOπ*)/S2(ππ*), were computed at the complete active space self-consistent field (CASSCF)/6-31G(d) theory level. The intensity patterns of the A-band resonance Raman spectra were analyzed, and the results, together with those of the CASSCF calculations, revealed that the major decay channel initiated from the S2(ππ*) state was S2, FCS2, min(ππ*)→S0 radiation.

Key words: 4-Nitroimidazole, Structural dynamics, Resonance Raman spectrum, CASSCF calculation, Vibrational spectrum, Electronic spectrum