Hc. Straub et al., ABSOLUTE PARTIAL AND TOTAL CROSS-SECTIONS FOR ELECTRON-IMPACT IONIZATION OF ARGON FROM THRESHOLD TO 1000 EV, Physical review. A, 52(2), 1995, pp. 1115-1124
Absolute partial cross sections from threshold to 1000 eV are reported
for the production of Ar-n+ (n = 1-4) by electron-impact ionization o
f argon. The total cross sections, obtained from an appropriately weig
hted sum of the partial cross sections, are also reported. These resul
ts are obtained with an apparatus incorporating a time-of-flight mass
spectrometer with position-sensitive detection of the product ions. Th
e simple apparatus design embodies recent developments in pressure mea
surement and particle detection and is believed to yield more reliable
results than those previously reported. For singly charged ions, the
overall uncertainty in the absolute cross section values reported here
is +/-3.5%. Previous measurements of absolute partial and total cross
sections are reviewed and compared with the present results.