Article,
Quantitative measurement of the deformation of ultra-thin platinum foils during adsorption and reaction of CO and O2
Surface Science, 600 (16): 3101 - 3109 (2006)
DOI: DOI: 10.1016/j.susc.2006.04.031
Abstract
An ultra-thin self-supporting Pt-foil with a thickness of 300�nm and
4�mm diameter has a heat capacity of only 10�muJ/K. Thus, even
small amounts of heat deposited within the thin metal foil cause
a significant temperature increase. During the adsorption of, for
example, CO heat in the order of 30�muJ/ML is released into the
metal. If the rim of a Pt(1�1�0) single crystal foil is rigidly mounted
on a substrate, a temperature increase of the foil induced by adsorption
and reaction of CO and O2 causes thermo-elastic stress. This will
lead to macroscopic deformations of the metal foil. To quantify these
deformations an imaging Michelson-interferometer was set up, capable
to detect small deflections of the ultra-thin Pt catalyst down to
10-20�nm. Adsorption of CO and O2 causes a clear mechanical response
of the Pt foil. Depending on sample temperature and partial pressures
of the reactants fronts and pulses of deformation were found. The
system can be calibrated by using continuous and chopped laser light.
The optical properties of the catalytic surface change in the presence
of adsorbates. This complicates the analysis, but can be avoided
in an improved setup.
Tags
- deformation;
- foils;
- formation,
- interferometer;
- microcalorimetry;
- pattern
- platinum
- science
- sensor;,
- surface
