The infrared and Raman spectra for crystalline 3, 5-dicyanoaniline (3, 5-DCA) and the laser induced fluorescence (LIF) excitation spectra of vacuum jet cooled molecules have been investigated. The ground S0 (A1) and excited S1 (B2) state geometries, charge distributions and vibrational frequencies of 3, 5-DCA have been evaluated by ab initio calculations. The Dushinsky matrices have been used for the mode correlation and assignments of the ...