Methods and apparatus for controlling contaminant deposition on a dynode electron-emmissive surface

The present invention relates to generally to components of scientific analytical equipment, and particularly to methods for extending the operational lifetime or otherwise improving the performance of dynodes used in electron multipliers. An aspect of the invention is embodied in a method for: (i) increasing the secondary electron yield of a dynode and/or (ii) decreasing the rate of degradation of electron yield of a dynode, the method comprising the step of exposing a dynode electron-emissive surface to an electron flux under conditions causing electron-impact induced removal of a contaminant deposited on the dynode electron-emissive surface. The conditions may be selected such that the electron-mediated removal is enhanced relative to a contaminant deposition process so as to provide a net decrease in the rate of contaminant deposition and/or a decrease in the amount of contaminant present on the dynode electron-emissive surface.