TY  - JOUR
A1  - Füchsel, Gernot
A1  - Tremblay, Jean Christophe
A1  - Klamroth, Tillmann
A1  - Saalfrank, Peter
T1  - Quantum dynamical simulations of the femtosecond-laser-induced ultrafast desorption of H2 and D2 from Ru(0001)
JF  - ChemPhysChem : a European journal of chemical physics and physical chemistry
N2  - We investigate the recombinative desorption of hydrogen and deuterium from a Ru(0001) surface initiated by femtosecond laser pulses. We adopt a quantum mechanical two-state model including three molecular degrees of freedom to describe the dynamics within the desorption induced by electronic transition (DIET) limit. The energy distributions as well as the state-resolved and ensemble properties of the desorbed molecules are analyzed in detail by using the time-energy method. Our results shed light on the experimentally observed 1) large isotopic effects regarding desorption yields and translational energies and 2) the nonequal energy partitioning into internal and translational modes. In particular, it is shown that a single temperature is sufficient to characterize the energy distributions for all degrees of freedom. Further, we confirm that quantization effects play an important role in the determination of the energy partitioning.
KW  - quantum dynamics
KW  - laser chemistry
KW  - isotope effects
KW  - surface chemistry
KW  - ultrafast reactions
Y1  - 2013
U6  - https://doi.org/10.1002/cphc.201200940
SN  - 1439-4235
VL  - 14
IS  - 7
SP  - 1471
EP  - 1478
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Füchsel, Gernot
A1  - Schimka, Selina
A1  - Saalfrank, Peter
T1  - On the role of electronic friction for dissociative adsorption and scattering of hydrogen molecules at a Ru(0001) surface
JF  - The journal of physical chemistry : A, Molecules, spectroscopy, kinetics, environment & general theory
N2  - The role of electronic friction and, more generally, of nonadiabatic effects during dynamical processes at the gas/metal surface interface is still a matter of discussion. In particular, it is not clear if electronic nonadiabaticity has an effect under "mild" conditions, when molecules in low rovibrational states interact with a metal surface. In this paper, we investigate the role of electronic friction on the dissociative sticking and (inelastic) scattering of vibrationally and rotationally cold H-2 molecules at a Ru(0001) surface theoretically. For this purpose, classical molecular dynamics with electronic friction (MDEF) calculations are performed and compared to MD simulations without friction. The two H atoms move on a six-dimensional potential energy surface generated from gradient-corrected density functional theory (DFT), that is, all molecular degrees of freedom are accounted for. Electronic friction is included via atomic friction coefficients obtained from an embedded atom, free electron gas (FEG) model, with embedding densities taken from gradient-corrected DFT. We find that within this model, dissociative sticking probabilities as a function of impact kinetic energies and impact angles are hardly affected by nonadiabatic effects. If one accounts for a possibly enhanced electronic friction near the dissociation barrier, on the other hand, reduced sticking probabilities are observed, in particular, at high impact energies. Further, there is always an influence on inelastic scattering, in particular, as far as the translational and internal energy distribution of the reflected molecules is concerned. Additionally, our results shed light on the role played by the velocity distribution of the incident molecular beam for adsorption probabilities, where, in particular, at higher impact energies, large effects are found.
Y1  - 2013
U6  - https://doi.org/10.1021/jp403860p
SN  - 1089-5639
VL  - 117
IS  - 36
SP  - 8761
EP  - 8769
PB  - American Chemical Society
CY  - Washington
ER  -