Inelastic scattering of NO from Ag(111): Internal state, angle, and velocity resolved measurements

Abstract

We have determined the velocity distributions of individual quantum states of NO scattering from Ag( 111) at specific scattering angles Of using molecular beam techniques to control the incidence energy E j and angle OJ' We find that the mean energies of scattered species E f depend weakly on 0tat low collision energies, but become increasingly independent of this parameter as E[ approaches 1.0 eV. This is true for all final rotation states J. The previously reported insensitivity of the final kinetic energy to J is found to apply at all scattering angles, so that E f vs Of curves for high J fall only slightly below those for low J. This system is highly translationally inelastic at high incidence energies, with up to 55% of EI being lost to phonons at E j = 1.0 eV. Angular distributions are relatively insensitive to J at low E j • but for high Ei the peak flux is found to shift away from the surface normal as Ei increases. The effect of the surface temperature only becomes apparent at low incidence energies. A search fur supernumerary rotational rainbows reveals no discernible oscillations even for the lowest surface temperatures~ We believe that these supernumerary oscillations may be damped by "surface corrugation" effects for this system. Discussion focuses on the observed anticorrelation between kinetic energy transfer to phonons and to rotation, the extent to which parallel momentum is conserved in this system, and energy-angle scaling laws for energy transfer. In this latter case we show that energy transfer in this system scales approximately with the quantity E[ cos OJ, over the full range of conditions covered.

The importance of accurate adiabatic interaction potentials for the correct description of electronically nonadiabatic vibrational energy transfer: A combined experimental and theoretical study of NO(v = 3) collisions with a Au(111) surface

“…36 This picture is corroborated by previously observed narrow angular distributions for NO(v = 0 → 1, 2, 3)/Au(111) scattering over a broad range of incidence energies; 23,25 final rotational distributions that depend strongly on incidence energy but only weakly on surface temperature, with rotational temperatures different from surface temperatures for NO(v = 0)/Ag(111) and NO(v = 0 → 1, 2, 3)/Au(111) scattering; 23,37 and by clearly non-thermal recoil translational energy distributions for NO(v = 3 → 3, 2, 1)/Au(111) scattering. 30 For incidence energies below 0.2-0.3 eV, it is known that trapping becomes significant for NO(v = 0, 2)/Au(111), with experimentally determined trapping probabilities of approximately 0.05 at E i = 0.3 eV, 0.15 at E i = 0.2 eV, and 0.38 .5.…”

Stereodynamics in state-resolved scattering at the gas–liquid interface

“…The majority of previous quantum-state-resolved gas-surface studies have been diatomic molecule and metal systems, which include NO ϩ Pt(111) (24), NO ϩ Ag(111) (23), and N 2 ϩ Ag(111) (21,22). The results of these studies provide an extraordinary physical picture for the interfacial dynamics of a molecular gas and metal surface.…”

“…Interestingly, this small, but finite, number of collisions is able to achieve final rotational/translational distributions well characterized by an IS temperature, albeit where T IS Ͼ Ͼ T S (13)(14)(15)(16). Such a temperature-like description of the IS channel contrasts drastically with the rainbow-like rotational distributions often observed in gassolid scattering (21)(22)(23)(24) and highlights the qualitative differences between atomically flat solid surfaces and dynamically rough liquid interfaces.…”

Classical theory of molecule-surface scattering: Application to C2H2 scattering from LiF

“…A large number of experiments have been carried out for the scattering of diatomic molecules from a variety of surfaces, with perhaps the largest number of such experiments involving NO as the scattering projectile. [2][3][4][5][6][7][8][9] Other diatomic molecules which have been studied include CO, 10,11 HF, 12 H 2 and its deuterated relatives, [13][14][15] HCl, 16 and N 2 . 17,18 The scattering of several larger molecules has also been investigated, for example CO 2 , 11 SF 6 , 19 NH 3 , 20 and CH 4 .…”