Nanoscale EELS analysis of oxides: composition mapping, valence determination and beam damage

Beam damage to ceria abrasive particles during EELS measurements with -1 nm probes of similar to 1 nA was negligible for typical analysis times (1-5 s). Ce3+ and tri-valent impurities reduce near-surface regions. Ce valence was measured from Ce M-5/M-4 white line ratios. By defocusing a 1 nA probe to similar to 5 nm, beam damage to nanoscale MgAl2O4 spinel was sufficiently slowed to allow spectrum imaging measurements of composition variations. Recording spectrum lines in TEM mode can be attractive when dose-rate rather than dose is the limiting factor in beam damage. Multivariate statistical analysis of data from a CoO-Co3O4 interface has revealed an additional interface-related component.