Detection of Metastable Atoms and Ions

Experimental work is presented concerning the detection of metastable singly charged ions by means of electron ejection from contaminated metal surfaces. By the use of suitable retarding potentials one can cause the current of reflected ions to cancel very nearly the current of electrons ejected by the ground state ions. This method increases the ratio of metastable signal to background signal by a factor of 300 or more and is comparable to what can be done by modulation of the metastable component. Some comments concerning the detection of metastable atoms by means of Auger electron ejection processes are included.