Experimental determination of the transmission factor for the Omicron EA125 electron analyzer

In this article a study of the transmission factor of the Omicron EA125 ana lyzer equipped with the universal lens is presented. The procedure is based on a model by Cross and Castle [J. Electron Spectrosc. Relat. Phenom. 22, 53 (1981)] and is applicable to every spectrometer which can be operated in the constant analyzer energy (CAE) and in the constant retarding ratio mea suring mode. The advantage of the method is its independence on the sample and on the inelastic mean free path of the electrons. We find that the tran smission factor for the CAE mode is proportional to E-kin(-1) for most meas uring setups. This dependence is predicted by theory for an ideal analyzer. Deviations from this behavior are observed if the retarding ratio for a gi ven kinetic energy is too small. The limit value of the retarding ratio for ideal behavior, i.e., an E-kin(-1) transmission factor, depends on the ana lyzer entrance slit aperture which has been selected. (C) 2000 American Ins titute of Physics. [S0034-6748(00)01811-6].