Two-photon ionization of xenon at 193 nm

A microwave bridge has been used in conjunction with an ArF excimer laser to measure the coefficient $\alpha$ for two-photon ionization of Xe at 193 nm. The bridge permits the measurement of ${\nu }_m$, the collision frequency for momentum transfer, and the display of the temporal history of the absolute electron density. Although considerably larger than previous estimates, the value of $\alpha$ reported here (4×${10}^{-32\mathrm{}}$ ${\mathrm{cm}}^4$ ${\mathrm{W}}^{-1\mathrm{}}$) is in agreement with the recent theoretical calculations of McGuire.