PHOTO-DISSOCIATION CROSS-SECTIONS OF NE-2(+), AR-2(+), KR-2(+), AND XE-2(+) FROM 3500-A TO 5400-A

The photodissociation (photoabsorption) cross sections of Ne2+, Ar2+, Kr2+, and Xe2+ have been measured from 3500 to 5400. The rare-gas dimer ions were produced in a drift-tube mass spectrometer, and the Kr+ and Ar+ ion laser lines were used as the photon source. The cross sections decrease monotonically with increasing photon wavelength from 3500 to 5000, and then increase with photon wavelength. The cross sections have values of 1.93, 13.3, 24.8, and 29.6 × 10-18 cm2 at (3569 and 3507) for Ne2+, Ar2+, Kr2+, and Xe2+, respectively. The current measurements are compared with various theoretical calculations. The dependence of the Ne2+ and Ar2+ cross sections on the effective kinetic temperature was investigated by increasing the ion drift velocity, and was attributed to vibrational excitation of the ions. © 1979 The American Physical Society.