Two-photon absorption in fused quartz and in water at the wavelength of 212.8 nm

Picosecond pulses of the fifth harmonic of a YAG : Nd laser were used to study nonlinear absorption in fused quartz and in water at the wavelength of 212.8 nm. The two-photon absorption coefficients of quartz and water were determined. In the approximation of the Gaussian shape for the laser pulses these coefficients were (7.5 ± 0.4)×10^-10 and (3.2 ± 0.3)×10^-10 cm W^-1 for quartz and water, respectively.