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Papers by Daniel Auerbach
Natural Sciences, 2021
The field of gas‐phase chemical dynamics has developed superb experimental methods to probe the d... more The field of gas‐phase chemical dynamics has developed superb experimental methods to probe the detailed outcome of gas‐phase chemical reactions. These experiments inspired and benchmarked first principles dynamics simulations giving access to an atomic scale picture of the motions that underlie these reactions. This fruitful interplay of experiment and theory is the essence of a dynamical approach perfected on gas‐phase reactions, the culmination of which is a standard model of chemical reactivity involving classical trajectories or quantum wave packets moving on a Born–Oppenheimer potential energy surface. Extending the dynamical approach to chemical reactions at surfaces presents challenges of complexity not found in gas‐phase study as reactive processes often involve multiple steps, such as inelastic molecule‐surface scattering and dissipation, leading to adsorption and subsequent thermal desorption and or bond breaking and making. This paper reviews progress toward understandin...
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007
Vibrational excitation of HCl molecules (m = 0 ! 1) has been observed when HCl molecular beams at... more Vibrational excitation of HCl molecules (m = 0 ! 1) has been observed when HCl molecular beams at energies of 0.59-1.37 eV are scattered from a Au(1 1 1) surface at low surface temperature (T s = 273 K). The incident and scattered HCl is probed state-selectively using 2 + 1 REMPI. The vibrational excitation probability depends strongly on incidence kinetic energy, E i , exhibiting a threshold near $E i = 0.57 eV. We measured the absolute vibrational excitation probability which varies from 10 À6 to 10 À5 over this energy range, 1-2 orders of magnitude higher than the thermal equilibrium expectation value. The magnitude of the excitation probability, the near specular angular distributions of the scattered m = 1 molecules and the dramatic narrowing of the angular distribution near threshold are all consistent with a direct translation to vibration (T-V) mechanical energy transfer mechanism.
Physical Review Letters, 2000
Measurements of vibrational excitation and deexcitation of NO͑y 2͒ scattering from a Au(111) surf... more Measurements of vibrational excitation and deexcitation of NO͑y 2͒ scattering from a Au(111) surface show that the probability of both processes increases strongly with the kinetic energy of the incident NO. These results are qualitatively consistent with a vibrational energy transfer mechanism involving electron-hole pairs but not with competing adiabatic models. The form of the energy dependence, and other features of the measurements, are not in accord with existing calculations.
Natural Sciences, 2021
The field of gas‐phase chemical dynamics has developed superb experimental methods to probe the d... more The field of gas‐phase chemical dynamics has developed superb experimental methods to probe the detailed outcome of gas‐phase chemical reactions. These experiments inspired and benchmarked first principles dynamics simulations giving access to an atomic scale picture of the motions that underlie these reactions. This fruitful interplay of experiment and theory is the essence of a dynamical approach perfected on gas‐phase reactions, the culmination of which is a standard model of chemical reactivity involving classical trajectories or quantum wave packets moving on a Born–Oppenheimer potential energy surface. Extending the dynamical approach to chemical reactions at surfaces presents challenges of complexity not found in gas‐phase study as reactive processes often involve multiple steps, such as inelastic molecule‐surface scattering and dissipation, leading to adsorption and subsequent thermal desorption and or bond breaking and making. This paper reviews progress toward understandin...
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007
Vibrational excitation of HCl molecules (m = 0 ! 1) has been observed when HCl molecular beams at... more Vibrational excitation of HCl molecules (m = 0 ! 1) has been observed when HCl molecular beams at energies of 0.59-1.37 eV are scattered from a Au(1 1 1) surface at low surface temperature (T s = 273 K). The incident and scattered HCl is probed state-selectively using 2 + 1 REMPI. The vibrational excitation probability depends strongly on incidence kinetic energy, E i , exhibiting a threshold near $E i = 0.57 eV. We measured the absolute vibrational excitation probability which varies from 10 À6 to 10 À5 over this energy range, 1-2 orders of magnitude higher than the thermal equilibrium expectation value. The magnitude of the excitation probability, the near specular angular distributions of the scattered m = 1 molecules and the dramatic narrowing of the angular distribution near threshold are all consistent with a direct translation to vibration (T-V) mechanical energy transfer mechanism.
Physical Review Letters, 2000
Measurements of vibrational excitation and deexcitation of NO͑y 2͒ scattering from a Au(111) surf... more Measurements of vibrational excitation and deexcitation of NO͑y 2͒ scattering from a Au(111) surface show that the probability of both processes increases strongly with the kinetic energy of the incident NO. These results are qualitatively consistent with a vibrational energy transfer mechanism involving electron-hole pairs but not with competing adiabatic models. The form of the energy dependence, and other features of the measurements, are not in accord with existing calculations.