A time-, angle- and kinetic-energy-resolved photoelectron spectroscopic study of tetrakis(dimethylamino)ethylene

The ultrafast electronic relaxation dynamics of tetrakis(dimethylamino)ethylene (TDMAE) following photoexcitation at ∼267 nm is investigated using the time-, angle- and kinetic-energy-resolved photoelectron spectroscopy method, since we are motivated by the experimental findings in a previous similar study (E. Gloaguen et al., J. Am. Chem. Soc., 2005, 127, 16529-16534). Based on the detailed analysis of the current high-quality data, the lifetime of the initially prepared ππ* state is found to be 50 ± 10 fs and it is clearly evident that an intermediate Rydberg state with a lifetime of 550 ± 50 fs plays a pivotal role in the photodynamics of TDMAE. In addition, a partial wave packet revival is also observed with a period of ∼500 fs. This coherent oscillation, which is attributed to a vibrational quantum beat associated with overtones of the low-frequency C-C twist vibration in TDMAE, survives the ultrafast internal conversion processes and finally damps on a time scale of the order of several picoseconds.