Question

20- (10 pts) a) The ionization energy for Si 3p electrons are 8.15eV and 2p electrons are 166.77eV. In an scanning electron microscope if an electron is emitted from the 2p orbital, that then gets filled with an electron from 3p orbital, what is the energy of the characteristic X-ray emitted b) What is the X-ray notation for such an X-ray? Is it visible in the spectrum below? c) In the spectrum below there are two peaks notated related to Si (Ka and Ka). Write which orbitals are associated with these peaks. (Note that KB is hardly visible next to the Au peaks) d) Comment on the energy difference between (Ka and KB) in relationship to part (a) Please ignore the energy difference between the sub-shells (e.g., L1,L2,L3 or M1,M2,M3,M4,M5) while answering this question 1400 1300 1200 1100 1000 SiK α 900 800 700 600 500 400 300 200 AuM NiL ci il. RuLß RuL a 0 0 4 (keV)

Answer 1

An electron from the L shell fills the vacancy and a Single k(alpha )x-ray is generated.The energy of X-ray is equal to the ionization energy of the k shell minus the ionization energy of the the L shell.

For Si,the ionization energy of L shell is 166.77ev,the ionization energy of M shell is 8.15 ev.

The characteristic x-ray spectrum for Si shows 2 spectral lines.The line at low energy results from ionization of the L shell with an electron from the M shell filling the vacancy

E=166.77-8.15 ev=158.62ev=0.158kev