Microanalysis to nanoanalysis: measuring composition at high spatial resolution

Abstract

Spatially resolved analysis of elemental, isotopic, and molecular constituents is possible with microanalysis and nanoanalysis techniques. At the micrometer scale of spatial resolution, electron probe X-ray microanalysis provides elemental coverage from beryllium to the actinides with detection limits in the range from 100 to 1000 parts per million (ppm). Secondary-ion mass spectrometry and laser microprobe mass spectrometry detect all elements and isotopes with detection limits from parts per billion to parts per million, and molecular signals can also be detected. Molecular microanalysis is primarily performed with photon detection techniques, including infrared, fluorescence, and Raman spectroscopies. Analytical electron microscopy and time-of-flight secondary-ion mass spectrometry extend spatial resolution to the 100 nm spatial level. Intermediate-voltage analytical electron microscopy operates to the 20 nm scale, and field-emission scanning transmission electron microscopy with electron energy loss spectrometry operates to the 2 nm scale. Atomic scale analysis is carried out with high-resolution lattice imaging electron microscopy, scanned tip microscopies, and field-ion microscopy.