Application of wavelet transform in mass spectrometry

In mass spectrometric studies, WT have been applied mainly in two areas including secondary ion mass spectrometry (SIMS) and instrumentation design. SIMS is a type of surface technique for trace analysis, determination of elemental composition, and the identity and concentrations of adsorbed species and elemental composition as a function of depth [46]. The application of wavelet denoising techniques to SIMS images has been studied by Grasserbauer et al. [47-50], and details about these studies are presented in another chapter of this book. 

With regard to instrumentation design, WT was applied to process real-time signals from the mass spectrometer. Shew [51] invented a new procedure for determining the relative ion abundances in ion cyclotron resonance mass spectrometry, by utilizing WT to isolate the intensity of a particular ion frequency as a function of position or time within the transient ion cyclotron resonance signal. In 1995, this new method was patented in the U.S. Shew explained that the WT intensity corresponding to the frequency of each ion species as a function of time can be fitted by an exponential decay curve. By 

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