Measurement of the wavelength-dependent photoionization cross section of Se*(1S) in the spectral region of 170-175 nm

The photoionization cross section of excited atomic selenium, Se(
¹
S
0
), obtained by photodissociation of OCSe, has been measured in the wavelength region of 170-175 nm using a tunable xenon laser. A minimum value, at 172 nm, was found to be
1.2 \times 10^{-20}
cm
²
, approximately ten times less than a recently calculated value. The photodissociation cross section for OCSe, at the same wavelength, was found to be
0.8 \times 10^{-16}
cm
²
, in good agreement with published work. The effect of an election cooling buffer gas upon the electron production from excited selenium was also investigated.