Crystal momentum is an interesting phenomenon.
Maybe you want to read my post #15 in the following thread: https://www.physicsforums.com/showthread.php?t=611109
I have never seen this discussed in solid state literature.
I am new to XPS Data analysis, and I have a .sle file that I got out of XPS Machine Software, and I am using CasaXPS to analyse the data. This software takes only .vms files. I want to convert the .sle to a .vms file for analysis. How or where can I do this? Any help on this will be deeply appreciated.