Quantum dynamical study of femtosecond photodesorption of CO from TiO2(110)

Abstract

The photodesorption of CO from TiO2(110) by femtosecond pulses is investigated with the Surrogate Hamiltonian approach. The aim of the study is to resolve the relaxation mechanism and forecast the lifetime of the exited state based on a microscopic description of the excitation and relaxation processes. The parameters characterizing the system are obtained from ab initio and Density Functional Theory-calculations with one parameter estimated from physical considerations and convergence studies. Two electronic states are considered and the relaxation is assumed to be due to the interaction of the excited adsorbate with electron hole pairs in the surface. Desorption probabilities and velocity distributions of the desorbing molecules are calculated and an exited state lifetime is predicted. Throughout this paper atomic units, i.e., ℏ = me = e = a0 = 1, have been used unless otherwise stated.

Photodesorption of H2O from Anatase-TiO2(101): A Combined Quantum Chemical and Quantum Dynamical Study

“…As this shoulderlike shape is only visible for resonance lifetimes above 60 fs, such values can be concluded for the present H 2 O/a-TiO 2 system. Interestingly, these are significantly longer than typical values for metal oxide surfaces, as for instance a resonance lifetime of τ = 14.7 fs found for the CO/r-TiO 2 (110) system …”

“…Interestingly, these are significantly longer than typical values for metal oxide surfaces, as for instance a resonance lifetime of τ = 14.7 fs found for the CO/r-TiO 2 (110) system. 56 Furthermore, the velocity distribution shown in Figure 10 so far does not include temperature effects, as the experiment was done at 100 K. Using the three additional vibronic states, their velocity distributions were normalized for the population of their respective vibronic wavepacket at 100 K and monitored at a resonance lifetime of τ = 60 fs (see Figure 11). In comparison with Figure 10, the low-velocity maximum at 1650 m s −1 appears throughout all four wavepackets as well.…”