33 cbems 164 xrd sem microanalysis lecture 13 34 a

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: icroanalysis: Lecture 13 ! 32 ZAF factors in Microanalysis! Atomic Number Effect: X-ray Absorption Effect: Fluorescence Effect: Z – Atomic Number Effect! •  Backscattering, R –  Some electrons are backscattered and leave sample without exciting an x-ray •  No energy loss therefore no x-ray •  BS electron yield from a Au:1 Al alloy will be dominated by the Au and this must be accounted for if a pure Al standard is used for Al analysis. •  Can model with Monte Carlo simulations •  Energy Loss, S –  Rate of energy loss due to inelastic scattering depends on Z CBEMS 164 – XRD, SEM & Microanalysis: Lecture 13 ! 33 CBEMS 164 – XRD, SEM & Microanalysis: Lecture 13 ! 34 A- X-Ray Absorption Effect! •  Once generated, x-rays have to traverse sample until they exit the top surface –  Some are absorbed, possibly ejecting inner shell electrons from their sites - inner shell ionization –  Higher keV results in a longer traverse path I/I0 = exp[-(µ/)(t)] µ/ is mass absorption coefficient F - Flourescence! •  Ionizations of inner atomic shells can result...
View Full Document

This note was uploaded on 01/16/2014 for the course CBEMS 164 taught by Professor Porter,j during the Fall '08 term at UC Irvine.

Ask a homework question - tutors are online