The 11th anti-Stokes Raman beam (116nm) has been obtained by the Raman scattering of KrF laser radiation in hydrogen at room temperature. Generation of the second- and third-Stokes order with photon-conversion efficiencies of 68% and 47%, respectively, has been obtained from a single-pass hydrogen Raman oscillator. We investigated the effects of optical breakdown by the laser beam on Raman scattering and found that the pumping efficiencies to anti-Stokes orders are reduced by the disturbance in the wave-front of the pump beam caused by the optical breakdown.