Photoionization cross section measurements of the 3pP1,3 excited states of helium in the near-threshold region

We present measurements of photoionization cross sections of the $3p\phantom{\rule{0.2em}{0ex}}^{1}P$ and $3p\phantom{\rule{0.2em}{0ex}}^{3}P$ excited states of helium, at threshold and near-threshold region $(0--0.2\phantom{\rule{0.3em}{0ex}}\mathrm{Ry})$. The experiments have been performed using a dc glow discharge and employed the saturation technique to determine the photoionization cross sections. A smooth frequency dependence of the cross section has been observed for both the excited states in accordance to the theoretical calculations. The measured values of the photoionization cross section, using a simple experimental setup, are in good agreement with the earlier reported theoretical and experimental values.