Direct picosecond time resolution of dissipative intramolecular vibrational-energy redistribution (IVR) in isolated molecules

Direct picosecond time resolution of dissipative IVR is reported for the first time. For jet-cooled anthracene with E_(vib) = 1792 cm^(−1), the unrelaxed fluorescence displays a fast decay of ≈75 ps, while the relaxed fluorescence displays a corresponding rise. The onset for dissipative IVR is related to the effective density of states and coupling matrix elements, and reflects the importance of time-resolved measurements