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A. Mathur et al.
Fig. 1 a Schematic of X-Ray photoelectron spectrometer; b Illustration of monochromatization of
X-Rays. Reprinted with permission from reference 1 Copyright (2019) Elsevier
XPS Instrumentation: XPS basically consists of a sample holder, an X-ray source,
electron analyser, etc. under ultra-high vacuum (UHV) chamber. The schematic of
an X-Ray photoelectron spectrometer is shown in Fig. 1a.
1. Vacuum chamber: The vacuum pressure lies in the range 10
–8 to 10
–10 mbar.
This ultra-high vacuum is required to serve the following purposes:
(a) To trap the electrons with lower energy, or that have lost their energy due
to inelastic scattering. These electrons contribute to the background of the
spectrum;
(b) To avoid formation of oxide layer over surface sensitive thin films.
For the samples, that become unstable under UHV conditions, they are
kept in sample introduction chamber for longer duration, so that they do not
release gas residuals or contaminate other materials in the analysis chamber.
Various type of pumps are used for pumping vacuum in the instrument- ion
gutter pumps, turbomolecular pumps, etc. A titanium sublimation pump
is always used to assist the primary vacuum pump to achieve the desired
vacuum level. To sanitise the instrument, frequent baking is also performed,
by heating the chambers in the temperature range of 100–160 °C.
Hence, there are two chambers in an X-Ray photoelectron spectrometersample introduction chamber and the analysis chamber. The samples are
loaded on a sample loader and are kept in the sample introduction chamber.
It is the chamber that comes in contact with the environment and prevents any
contamination or adsorption of atmospheric gases into the analysis chamber.
The vacuum level of sample introduction chamber is usually lower than that
of analysis chamber.
2. X-Ray source: When a high energy electron source strikes metallic anode, XRays are generated. The source of high energy electrons could be from a filament
based on thermionic emission i.e. on heating the filament it emits electrons (for
A. Mathur et al.
Fig. 1 a Schematic of X-Ray photoelectron spectrometer; b Illustration of monochromatization of
X-Rays. Reprinted with permission from reference 1 Copyright (2019) Elsevier
XPS Instrumentation: XPS basically consists of a sample holder, an X-ray source,
electron analyser, etc. under ultra-high vacuum (UHV) chamber. The schematic of
an X-Ray photoelectron spectrometer is shown in Fig. 1a.
1. Vacuum chamber: The vacuum pressure lies in the range 10
–8 to 10
–10 mbar.
This ultra-high vacuum is required to serve the following purposes:
(a) To trap the electrons with lower energy, or that have lost their energy due
to inelastic scattering. These electrons contribute to the background of the
spectrum;
(b) To avoid formation of oxide layer over surface sensitive thin films.
For the samples, that become unstable under UHV conditions, they are
kept in sample introduction chamber for longer duration, so that they do not
release gas residuals or contaminate other materials in the analysis chamber.
Various type of pumps are used for pumping vacuum in the instrument- ion
gutter pumps, turbomolecular pumps, etc. A titanium sublimation pump
is always used to assist the primary vacuum pump to achieve the desired
vacuum level. To sanitise the instrument, frequent baking is also performed,
by heating the chambers in the temperature range of 100–160 °C.
Hence, there are two chambers in an X-Ray photoelectron spectrometersample introduction chamber and the analysis chamber. The samples are
loaded on a sample loader and are kept in the sample introduction chamber.
It is the chamber that comes in contact with the environment and prevents any
contamination or adsorption of atmospheric gases into the analysis chamber.
The vacuum level of sample introduction chamber is usually lower than that
of analysis chamber.
2. X-Ray source: When a high energy electron source strikes metallic anode, XRays are generated. The source of high energy electrons could be from a filament
based on thermionic emission i.e. on heating the filament it emits electrons (for