The essential features and the performance data of a recently developed secondaryhyphen;neutral microprobe are described which interfaces the wellhyphen;established technique of electron gas (plasma) posthyphen;ionization with a highhyphen;transmission magnetic sector mass spectrometer. Smallhyphen;area analysis is accomplished by means of a separate highhyphen;brightness liquidhyphen;metal (Ga+) ion source. For 20 keV Ga+ions and 1 nA beam current the intensities of posthyphen;ionized sputtered neutrals amount to some 103counts/s for pure elements, and secondary neutral micrographs can be acquired with an image resolution in the mgr;m range. Due to the high transmission of the mass spectrometer secondaryhyphen;neutral intensities up to 109counts/s per 1 mA primary current can be obtained in the direct bombardment mode (i.e., by extracting the sputtering beam out of the plasma), thus extending the detection limit down to the 10 ppb regime. Furthermore, the instrument can be operated at high mass resolution (M/Dgr;M=9500) providing the option of isotope analysis by means of secondaryhyphen;neutral mass spectrometry.
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