VUV laser in the Lyman band of molecular hydrogen pumped by fs titanium-sapphire laser pulses

We report lasing at 160 nm in the Lyman band of molecular hydrogen. The laser is pumped by 200 mJ/150 fs pulses from the ATLAS titanium-sapphire laser at our institute. The pump pulses are focused at an angle of incidence of 60/spl deg/ onto a 9-cm-long gold target to a line focus, generating traveling-wave excitation. With 80 mbar of hydrogen in the target chamber we measure an average gain of 1.1 cm/sup -1/ and achieve a total gain-length product of 10. The evaluation of the far-field pattern shows that the beam originates from a region with an electron density of 5/spl times/10/sup 15/ cm/sup -3/. A simple model of the H/sub 2/ laser is presented which explains the main part of our observations and supports a pump mechanism of photoelectron pumping.