Harmonic generation in the discrete spectral region of xenon using broadband femtosecond laser pulses

The conversion of 34-fs Ti: sapphire laser pulses into the wavelength region 105 - 210 nm has been studied in xenon for laser intensities up to 5 x 10(13) W/cm(2). A strongly structured, pressure-dependent emission spectrum is observed. Radiation is detected in regions expected for the 5th and 7th harmonics but also in regions in between. In the resonance region (lambda < 147 nm), self-phase-modulation processes in the conversion medium together with phase-matched, efficient harmonic generation in negative-dispersive spectral regions explain the observations. Broadband emission is detected in the resonance-free, positive-dispersive spectral region 155 - 210 nm. Emission from the xenon dimer is superimposed on a 'direct' 5th-harmonic signal.