Kinetics and energy transfer of gas-surface scattering

Technical Report · Mon Aug 01 04:00:00 EDT 1983

OSTI ID:5750101

Lin, T H

The residence time of CO on Pt(111) and Pt(557) indicates that while CO can be adsorbed at both step and terrace sites, the desorption kinetics are controlled by the steps. The kinetics of NO/Pt were found to be more complex than those of CO/Pt. The data indicate that one high adsorption energy state is sampled above 525K and a lower adsorption energy state appears suddenly below 480K. The distribution of energy among all the modes has been measured for NO scattered from Pt(111). The translational and vibrational energy accommodation coefficients are nearly equal to one for T/sub s/ < 900K and deviate from unity above this temperature due to nonequilibrated desorption. The rotational energy acommodation is very poor compared with that of the other two modes. The H/sub 2/-D/sub 2/ exchange reaction on Pt(557) was found to proceed via a Langmuir-Hinshelwood mechanism. Although the angular distribution of the HD product is slightly peaked at the normal, the velocity distribution is slightly colder than the substrate and the deviation increases as the detection angle increases. With atomic hydrogen and deuterium incident beams, the velocity of desorbing HD molecules increases as the crystal temperature decreases from 300 to 200K. At 200K, the velocity distribution is wider than Maxwellian and there is considerable HD leaving the surface with 1915K translational energy. The waveform indicates that the residence time decreases for some of the incident atoms from 300 to 200K, and that at high coverages some of the incident atoms can recombine before reaching thermal equilibrium.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5750101
• Report Number(s): LBL-16380; ON: DE84001838
• Country of Publication: United States
• Language: English

Related Subjects

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ADSORPTION
BEAMS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
DESORPTION
DEUTERIDES
DEUTERIUM
DEUTERIUM COMPOUNDS
ELEMENTS
HYDROGEN
HYDROGEN COMPOUNDS
HYDROGEN DEUTERIDE
HYDROGEN ISOTOPES
ISOTOPES
ISOTOPIC EXCHANGE
LIGHT NUCLEI
METALS
MOLECULAR BEAMS
NITRIC OXIDE
NITROGEN COMPOUNDS
NITROGEN OXIDES
NONMETALS
NUCLEI
ODD-ODD NUCLEI
OXIDES
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
RECOMBINATION
SCATTERING
SORPTION
STABLE ISOTOPES
SURFACE PROPERTIES
SURFACES
TRANSITION ELEMENTS