Assessing charging effects on spectral quality for X-ray microanalysis in low voltage and variable pressure/environmental scanning electron microscopy.
Energy dispersive X-ray spectrometry of uncoated insulators performed at low beam energy (incident energy < or = 5 keV) and in the variable pressure scanning electron microscope and the environmental scanning electron microscope is subject to spectral artifacts. Charging decelerates the incident beam electrons and reduces the impact energy, lowering the available overvoltage to excite characteristic X-ray peaks. The Duane-Hunt limit of the X-ray bremsstrahlung continuum is commonly used as a diagnostic of charging. Dynamic charging effects can hide the true impact of charging on the X-ray spectrum. Careful examination of the behavior of the X-ray spectrum with time and other variables is needed to avoid spectral artifacts, particularly on relative X-ray intensities.
Newbury
Dale E
DE
National Institute of Standards and Technology, Gaithersburg, MD 20899-8371, USA. dale.newbury@nist.gov