Question

Compare and contrast EDS and XPS techniques in terms of i) working principle and ii) limitations of practical use.

Answer 1

Solution:

EDS	XPS
It gives the details about the bulk concentration about the sample	It gives the details about the composition of the surface of the material
Very little information about the oxidation state of the elements	It analyses and gives full information about the oxidation state of the elements
Principle: The capacity of the high electromagnetic radiation to eject the electrons that are not in the outermost shell i.e core electrons from the atoms in the sample. This principle is known as Moseley's law. It can determine the relation between the frequency of light released and the atomic number of the atom.	Principle: When a beam of X- rays strikes the surface of the material the kinetic energy of the electrons that are emitted from the surface are being analyzed and a photoelectron spectrum is recorded by counting ejected electrons over a range of kinetic energy of electrons. Different peaks will appear due to the different kinetic energy of each element.
Limitations: If the concentration of element is too low then the sufficient energy will not adequate to measure its proportion EDS does not work for the elements with a low atomic number. Example: Hydrogen and helium.	Limitations: The sample size must be very low The relative error is there during the analyzing of the sample Sample must be compatible with the high vacuum environment