Imaging experiments, procedure

FIGURE 12.1 General procedure for MALDI MS imaging experiments in profiling (left side) and imaging (right side) modes. 

ToF-SIMS measurements are conducted on a PHI TRIFT III instrument (Physical Electronics USA, Chanhassen, MN, USA). This protocol could easily be modified for use with other ToF-SIMS instruments. In addition, it is anticipated that the above preparation procedure will also be applicable to single-cell imaging experiments using a variety of IMS techniques, including single-cell MALDI. 

Vrakking MJJ (2001) An iterative procedure for the inversion of two-dimensional ion/photoelectron imaging experiments. Rev Sci Instram 72 4084... 

Two different types of calibration marks are used in our experiments, planar circles and circular balls. The accuracy of the calibration procedure depends on the accuracy of the feature detection algorithms used to detect the calibration marks in the images. To take this in account, a special feature detection procedure based on accurate ellipses fitting has been developed. Detected calibration marks are rejected, if the feature detection procedure indicates a low reliability. 

As I look back at this experience, it was an awesome adventure to be alone, during and for an interval of time after this discovery, with the apparatus showing one new effect after another, when there was no one in the Illinois Physics Department experienced in NMR with whom I could talk. Little did the early NMR resonance community realize that the analogue of spin echo hidden memory contained in excited phases of all kinds of states of matter, including plasmas, would be obtained in the future by use of optical laser, electric, and acoustic pulses as well. And now today the use of spin echoes is a standard procedure for magnetic resonance imaging of the human body for medical diagnosis. 

Experimentally, the EMD function p(q) can be reconstructed from a set of Compton profiles J qz ) s, and B( r) from the EMD. However, A Air) is not a direct experimental product. By combining the experimental B(r) with theoretical B aik (r), we need to derive a semiexperimental AB(r). Since the atomic image is very weak, many problems must be cleared in experimental resolution, in reconstruction (for example, selection of a set of directions and range of qzs), in various deconvolution procedures and so on. First of all, high resolution experiments are desirable. 

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