Two-photon excitation spectroscopy of 1,5–Diphenyl-1,3,5-hexatriene using phase modulation
We have used two-photon Fourier transform spectroscopy to investigate the first singlet excited state (S1) of a prototypical polyene molecule 1,5—Diphenyl-1,3,5-hexatriene. As the S1 state in the polyenes is a one-photon forbidden transition, the structure of its vibrational levels cannot be studied using resonant linear excitation. Although this level is accessible with two-photon excitation, pre