Proton microprobe with windowless-exit port

Construction and use of a windowless-exit port with a proton microprobe apparatus is described. The use of a differential-pumping system permits bombardment of samples at atmospheric pressure without the problems caused by passing the beam through thin foils. Methods used for fabrication of beam collimators and for measurement of the beam diameter are discussed. The sensitivity for trace element determination by observation of K X-rays is given. Sample spectra obtained are presented and contrasted with results obtained with a scanning electron microscope with energy-dispersive X-ray detection. The localization of Zn in a rat incisor is given to demonstrate the type of data uniquely obtainable with the proton microprobe. (Auth.)