Is the large molecular deformation in TICTphenomenon really twisting mode?

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TICT phenomenon was firstly observed by E. Lipert et al at 1962. The interpretation and nomenclature was carried out by K. Rotkiewicz et al at 1973. Many world-wide scientists have as far confirmed it in many aromatic molecules consisting of donor and acceptor chromophers. Its concept has once seemed to be established. We have, however, thought it doubtful whether the large molecular deformation in TICT phenomenon is really twisting mode, although we could have recognized 'large deformation and charge transfer process' in the interpretation. With help of the Grant-in-Aid for Scientific Research (C)(2), the check investigation has been carried out for two years. Using a supersonic-jet laser spectroscopy we observed the S_0-S_1 electronic transitions of some of representative TICT molecules. The detail analysis of them should lead to the elucidation on the basis of the following idea, the S_1 and TICT states vibronically and mutually interact because of their energetic proximity. As a result, we observed the tangle vibronic pattern, indicating the electronic-state mixing, in the S_0-S_1 electronic transitions of jet-cooled p-cyanophenylpyrrol. The analysis leads to two conclusions,1. Upon the electronic excitation, the dihedral angle between the pyrrol and benzonitrile planes decreases from 39 to 20 degrees.2. Large deformation occurs along the direction in the 394 cm^<-1> vibrational coordinate.The explicit vibronic assignment of the mode has not yet completed and in progress.