Temperature rises produced by a molecular beam striking a Pt surface
- Brown Univ., Providence, RI (USA)
A platinum surface initially at room temperature is exposed to intense molecular beams of He, Ar, H{sub 2}, N{sub 2}, and SF{sub 6} emerging from a nozzle also at room temperature. The mass of the platinum is small, so after a few minutes it reaches a steady temperature uniform throughout the sample. Because the rate of heat loss to the surroundings is low, a thermocouple records temperature rises that for pure gases are as much as 30 K and that for mixtures of He with Ar can exceed 100 K. Interpretation of the results shows that these rises can be understood quantitatively and thus provide information about energy transfer occurring when gaseous molecules collide with surfaces. In particular the method gives (1) a way of measuring the temperature T{sub s} a surface attains at steady state due to interaction with gas molecules in the absence of heat conduction or radiation, (2) a simple determination of the average kinetic energy E{sub i} = 2k{sub B}T{sub s} of an incoming atomic beam without the need for measurement of the velocity distribution or the flux in the beam, and (3) a quantity {gamma} that, like an energy accommodation coefficient, is a measure of the effect of the temperature of the surface on the scattering.
- DOE Contract Number:
- FG02-85ER13441
- OSTI ID:
- 7243748
- Journal Information:
- Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Journal Issue: 18 Vol. 93:18; ISSN 0022-3654; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400000 -- Chemistry
400200 -- Inorganic
Organic
& Physical Chemistry
640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ARGON
BEAMS
DATA
DATA ANALYSIS
ELEMENTS
EXPERIMENTAL DATA
FLUIDS
GASES
HELIUM
HYDROGEN
INFORMATION
MEASURING INSTRUMENTS
MEASURING METHODS
METALS
MOLECULAR BEAMS
NITROGEN
NONMETALS
NUMERICAL DATA
PLATINUM
PLATINUM METALS
RARE GASES
SURFACES
THERMAL ANALYSIS
TRANSITION ELEMENTS