Particle-beam interface background

The corresponding mass spectrum of the main peak is shown in Fig. 7-55 (top) and compared to that of a respective standard (bottom). In both cases, the background signal has been subtracted. Smaller signals such as m/z 104 and m/z 186 correspond to p-xylenesulfonic acid, m/z 94 and m/z 158 to benzenesulfonic acid, which are both present as impurities. Although the application of a particle-beam interface is limited to analytes with a significant vapour pressure in the... 

Field Emission Gun with Energy Dispersive X-ray detection (FEG/EDX) interfaced with MRS is illustrated in Fig. 8, where it is observed that the particle has undergone changes after exposure to the electron beam. In addition, Raman spectra obtained after exposure to the electron beam showed band broadening, higher background and lower spectral quality. To this end, the importance of a robust protocol to be used for the analysis of environmental particles (especially of the finer fraction) with an interfaced two tier approach has been illustrated. It also seems from these preliminary observations that the protocol may have to be particle type specific. In addition, particle behaviour when exposed to the interfaced instrument may not mirror its behaviour when analysed under stand-alone conditions. 

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