Recent Developments in Ultrafast Time-Resolved Vibrational Spectroscopy of Electronically Excited States

Developments of three new time-resolved vibrational spectroscopies and their applications to electronically excited states are reviewed. Transformlimited picosecond time-resolved Raman spectroscopy has been used to study the vibrational dynamics of trans-stilbene in the lowest excited singlet state. Picosecond time-frequency two-dimensional multiplex Coherent Antistokes Raman Scattering spectroscopy has been used to probe the structure of diphenylacetylene in the lowest and the second lowest excited singlet states. Nanosecond time-resolved dispersive infrared spectroscopy has detected the singlet and triplet intramolecular charge transfer states of 4-(di-methylamino)benzonitrile. Strong evidence for a charge transfer structure has been obtained.