Surface analysis by electron spectroscopy at high pressures
C. J. Powell
J. Vac. Sci. Technol. 15(2), 549-552 (1978).
Abstract:
Surface analyses are now made by techniques such as Auger electron spectroscopy (AES), x-ray photoelectron
spectroscopy (XPS), and appearance potential spectroscopy (APS). These techniques utilize low-energy electrons
and have high surface sensitivity but cannot be used at high pressures
[
10-4
Torr(10-2 Pa)]. Optical techinques
can be used at high pressures but their surface sensitivity is poor. It is proposed to combine these approaches
by using the high-pressure gas as a converter. Two situations are considered. First, variable-energy x-rays are
used to produce variable-energy photoelectrons from the gas which impinge on the sample; these electrons
constitute a suitable source for APs. Second, the variable-energy x-rays produce photoelectrons from the
sample (XPS) of variable energy; these electrons can be detected using the gas for APS. In both cases, the
derivative of the x-ray yield from the gas-sample cell is measured as a function of incident x-ray energy;
features in the derivative spectrum can be correlated with the core levels of surface atoms of the sample.
Design calculations based on x-ray intensities from available sources indicate that the proposed method could
only be useful for specialized applications.
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