An experimental comparison of the total-electron-yield and conversion-electron-yield modes for near-surface characterization using X-ray excitation

Abstract

The electron yield technique is a very useful method for studying near-surface information of a thick sample because of the shallowness of the electron escape depth. In the present study, the glancing-angle dependence of the total electron yield (TEY) and the conversion electron yield (CEY) was measured at a 13 keV photon energy. It was found that the signal intensity in the CEY mode was larger than that for the TEY mode because air molecules are ionized by high-energy electrons emitted from the sample to form ion-electron pairs in air at atmospheric pressure. In addition, the probing depth for the TEY mode was found to be shallower than that for the CEY mode. The difference is due to the relative contribution of low-energy electrons emitted from the sample in the CEY mode being smaller than in the TEY mode. Thus high-energy electrons are selectivity detected in the CEY mode. Estimates for the value of the probing depth of the TEY and CEY modes are given from calculations.