Compositional analysis resolution capability

In addition to MS/MS with CID to obtain structural information, it is also useful to use high-resolution exact mass measurements to confirm the elemental compositions of ions. Essentially, exact mass measurements permit the unambiguous composition analysis of low-molecular-weight compounds (mol. wt. <500) through precise and accurate mlz measurements. The types of mass spectrometers capable of exact mass measurements include magnetic sector mass spectrometers, QTOF hybrid... 

Surface chemical changes created by these surface chemical reactions will be monitored by Electron Spectroscopy for Chemical Analysis (ESCA)(2), a very powerful spectroscopic technique for investigating surface compositions extending from 1-20 monolayers in depth from the surface. When the spectrometer is equipped with angle resolution capability, it also offers a means of non-destructive depth profiling of the upper 50A of substrate layers. 

Having seen the power (and limitation) of nexafs spectroscopy in the preceding sections, one can readily envision the enhanced utility of nexafs spectroscopy as a characterization tool that would result from the addition of high spatial resolution capabilities. Since the spectroscopic sensitivity to specific moieties and functional groups can in many or even most cases be exceeded by ir, nmr, and Raman spectroscopies, nexafs microscopy will have to exceed the spatial resolution of these other spectroscopy techniques in order to be truly useful. To date, nexafs microscopy has surpassed a spatial resolution of 50 nm both in transmission to measure bulk properties (75-77) and in a reflection geometry to study surfaces (78,79). This level of spatial resolution is at least an order of magnitude better than what can be accomplished with complementary compositional analysis techniques. Future developments in nexafs microscopy might achieve a spatial resolution of a few nanometers (80,81). In addition, nexafs microscopy has exceptional surface sensitivity of about 10 nm, a sensitivity that could be improved to about 1 nm with photoemission electron microscopes (peem s) that incorporate a bandpass filter (80-82). 

Spectral resolution and detection limit are two important parameters in composition analysis. Spectral resolution is the capability of an analytical... 

Resolution is moderate and not capable of accurate mass analysis sufficient to resolve different elemental compositions of the same nominal mass. 

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