3-D
SIMS
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What is going on here? |
This picture shows what happens during a three-dimensional SIMS measurement. At the beginning of the measurement (Layer 0) the primary ion beam rasters over the sample surface and gives us some information about the composition of the uppermost layers of the sample in an area of 256 x 256 micrometer. In this picture, the distribution of carbon is shown in false-color mode with the color coding shown below. "Beige" represents a carbon-free area, which covers most of the sample. Low concentrations of carbon are indicated by "Black", while "Red" and "Yellow" show increasingly higher concentrations of carbon in the sample. During a SIMS measurement, the sample is sputtered (i.e. eroded) away layer by layer. This means that the chemical information is coming from increasingly deeper layers of the sample during the course of a measurement. In the picture this is visualized by the beige square, which is moving slowly down through the volume that is being measured. As can be seen, carbon is present in the sample in the form of a heterogeneous contamination which is three-dimensionally distributed throughout the sample. During the course of the measurement, it can be seen how some of these contaminants appear to "pop up", grow bigger and then smaller again while they are being sputtered away. The picture shows data from an actual 3-D SIMS measurement. In real life, however, this measurement is not repeatable (as in this animated GIF sequence) because material from the sample is sputtered away and we are left with a rectangular crater in the sample. If you don't see any animation in the picture above, you probably need to change some of your browser's preferences. Make sure that "Animated GIFs" and "Looping" are enabled. |
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