A finite temperature theory of rotationally inelastic diffraction: H sub 2 , HD, and D sub 2 on Cu(100)

Journal Article · Sun Oct 15 04:00:00 EDT 1989 · Journal of Chemical Physics; (USA)

DOI:https://doi.org/10.1063/1.456739· OSTI ID:5397944

Cruz, A J; Jackson, B ^[1]

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1. Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003 (US)

The rotationally inelastic diffraction probabilities for H{sub 2}, HD, and D{sub 2} from Cu(100) were computed as a function of surface temperature. The surface is treated in a quantum mechanical fashion using a recently developed formalism. The center of mass molecular translational motion is treated semiclassically, using Gaussian wave packets (GWPs), and the rotations are described quantum mechanically. Strong attenuation of the phonon elastic diffraction peaks with temperature is observed. This Debye--Waller-like attenuation increases with increasing molecular mass and kinetic energy, and decreases as the peaks become more off-specular. The phonon summed rotation--diffraction probabilities show a moderate temperature dependence for the most part. The 0{r arrow}2 rotational excitation of D{sub 2} appears to be strongly phonon assisted above 300 K. At low temperatures our method reproduces the selection rules predicted by previous studies. As the temperature is increased these selection rules become less restrictive. The probability distribution for a scattering molecule exchanging an amount of energy {Delta}{ital E} with the surface was also computed. Rayleigh phonons were found to dominate the energy transfer, with bulk vibrations becoming more important for larger molecular masses, beam energies, and surface temperatures.

• OSTI ID: 5397944
• Journal Information: Journal of Chemical Physics; (USA), Journal Name: Journal of Chemical Physics; (USA) Vol. 91:8; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

656003* -- Condensed Matter Physics-- Interactions between Beams & Condensed Matter-- (1987-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BEAMS
COHERENT SCATTERING
COLLISIONS
COPPER
DEUTERIDES
DEUTERIUM
DEUTERIUM COMPOUNDS
DIFFRACTION
ELEMENTS
ENERGY LEVELS
ENERGY TRANSFER
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
HYDROGEN
HYDROGEN COMPOUNDS
HYDROGEN DEUTERIDE
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
METALS
MOLECULAR BEAMS
MOLECULE COLLISIONS
NONMETALS
NUCLEI
ODD-ODD NUCLEI
PHONONS
QUASI PARTICLES
ROTATIONAL STATES
SCATTERING
STABLE ISOTOPES
TEMPERATURE DEPENDENCE
TRANSITION ELEMENTS