title: EELS log-ratio technique for specimen-thickness measurement in the TEM.
abstract: We discuss measurement of the local thickness t of a transmission microscope specimen from the log-ratio formula t = lambda ln (It/I0) where It and I0 are the total and zero-loss areas under the electron-energy loss spectrum. We have measured the total inelastic mean free path lambda in 11 materials of varying atomic number Z and have parameterized the results in the form lambda = 106F (E0/Em)/ln (2 beta E0/Em) where F = (1 + E0/1,022)/(1 + E0/511)2, the incident energy E0 is in keV, the spectrum collection semiangle beta is in mrad, and Em = 7.6Z0.36. This formulation should allow absolute thickness to be determined to an accuracy of +/- 20% in most inorganic specimens.
authors.affiliation: Physical Metallurgy Research Labs, Ottawa, Ontario, Canada.
authors.forename: T
authors.initials: T
authors.lastname: Malis
authors.forename: S C
authors.initials: SC
authors.lastname: Cheng
authors.forename: R F
authors.initials: RF
authors.lastname: Egerton
mesh_terms: D008433:Mathematics; D008854:Microscopy, Electron / Q000379:methods*; D008867:Microtomy / Q000379:methods*