Page 262 - Inorganic Mass Spectrometry - Fundamentals and Applications

248 Delmore

of voltage spread across the face of the emitter, as mentioned in the preceding sec-
tion. Thus, even a OS-V spread across the emitter face causes considerable defo-
cusing.
to
This ion imager has allowed answers be obtained to the question, Where
on the emitter do the ions originate? All of the systems studied to date emit ions
from the surface of the main body of the emitter. This is illustrated in the images
presented in Fig. 6.4a-d. The photographs of the first three of these emitters (CS+
I"
in Fig. 6.4a, Reo," in Fig. 6.4b, in Fig. 6.4~) show the surface topographical fea-
tures of the face of the solid emitter, with ion emission clearly emanating from the

a b

c
(a) Image of CS+ emission from cesium zeolite. Note enhanced emission from
the cracks. (b) Image of Reo,- emission from a perrhenate emitter. (c) Irnage of I- emis-
sion from an iodide emitter. (d) Image of EW emission from a molten glass ion emitter.