Comparison of detection limits for EELS and EDXS

摘要: Simultaneous measurements have been made in the scanning transmission electron microscope to determine relative microanalytical sensitivities for energy loss (EELS) and energy-dispersive x-ray spectroscopies (EDXS). A photodiode-array parallel detector was used EELS, an ultrathin window Si(Li) subtending a solid angle of 0.18 sterad EDXS. Energy spectra were acquired first or second difference mode reduce channelto-channel gain variations detect weak signals on large backgrounds. Both EELS EDXS data analyzed using multiple least squares procedures fit reference spectra; this gave not only fitting coefficients but also their standard deviations. Results showed that is method choice analysis elements with Z 10. For higher atomic numbers (10 25) preferable if K edge used. However, has sensitivity most number range L23 analyzed. sodium detection limits are approximately factor 10 better EELS. As increases becomes smaller although still significant advantage phosphorus. The occurence "white-line" resonance at > 20 boosts calcium iron about same sensitivity. Calculated estimates reasonable agreement experimental data.