THE INFLUENCE OF SPECIMEN TOPOGRAPHY ON X-RAY MICROANALYSIS ELEMENT MAPPING

The effect of specimen topography on x-ray microanalysis element mapping was studied with an electron microprobe and a scanning electron microscope equipped for x-ray detection. Using the lemma and palea of rice inflorescences as models, we determined that specimen topography can physically limit the detection of x-rays and thus lead to erroneous element mapping data. Any geometrical point on a specimen interfering with a straight line from the point of excitation to the detector will cause an absorptive shadow area on the element map. Electrons impinging on a sample surface cause emissions to occur in all directions. Emissions with sufficient energy (x-rays and backscattered electrons) can strike a topographical point different from the location of the focused electron beam, causing detectable x-ray excitation. This phenomenon will also result in erroneous element map data. Methods of recognition of specimen topographical effects on x-ray microanalysis are discussed.