Why oxygen % in Al alloy is not decreasing significantly while moving towards bulk after etching using X-Ray Photoelectron Spectroscopy?

While analysing the Al alloy sample via XPS, I am getting the Oxygen value of 80% on the surface. Then I etched with an interval of 30sec, 30 sec, 1 min, 5 min, 10 min. The last etched surface...

18 May 2020 2,722 4 View