Internal conversion, time-resolved photoelectron

Figure 8. Time-resolved photoelectron spectra revealing vibrational and electronic dynamics during internal conversion in DT. (a) Level scheme in DT for one-photon probe ionization. The pump laser prepares the optically bright state S2. Due to ultrafast internal conversion, this state converts to the lower lying state Si with 0.7 eV of vibrational energy. The expected ionization propensity rules are shown S2 —> Do + e (ei) and Si —> D + (b) Femtosecond time-...

In order to study the viscosity effect on the quenching of triplet excited state of (53) by TEMPO, chemically induced dynamic electron polarization and transient absorption spectra have been measured in ethylene glycol, 1,2-propanol and their mixtures. The results indicate that the quenching rate constant is viscosity-dependent and decreases linearly with the increase in solvent viscosity. The spectroscopy and dynamics of near-threshold excited states of the isolated chloranil radical anion have been studied using photoelectron imaging taken at 480 nm, which clearly indicates resonance-enhanced photodetachment via a bound electronic excited state. Time-resolved photoelectron imaging reveals that the excited state rapidly decays on a timescale of 130 fs via internal conversion. ... 

Although in the case of pyrazine the interpretation is complicated by cross-term signals and auto-ionizing Rydberg states, the experimental and theoretical investigations nevertheless demonstrate the considerable potential of femtosecond time-resolved photoelectron spectroscopy. As a beautiful example of a more favorable case, Stolow and coworkers have recently presented time-resolved ionization studies on decatetraene. In direct analogy to the discussion presented above, they managed to monitor the S2 Si internal conversion associated with a conical intersection in real time. 

D. R. Cyr and C. C. Hayden, /. Chem. Phys., 104,771 (1996). Femtosecond Time-Resolved Photoionization and Photoelectron-Spectroscopy Studies of Ultrafast Internal Conversion in 1,3,5-Hexatriene. 

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