The electron-beam pumped XeF(C yields A) excimer has been investigated as a novel gain medium for ultrashort pulse, high power amplification in the visible spectral region over a wide range of laser pulse durations. Gain measurements for 100 ps and 800 fs pulses resulted in a small signal gain coefficient of 3%/cm and a saturation energy density of 80 mJ/cm2. For 250 fs pulses, a saturation energy density of 50 mJ/cm2 was observed. Narrowband absorbers in the XeF(C yields A) spectrum could be bleached out, yielding a smooth gain profile of 60 nm bandwidth. An unstable resonator was designed with particular consideration of the small XeF(C yields A) gain coefficient and optimized energy extraction in a single pulse output. A maximum pulse energy of 275 mJ was obtained by amplification of 250 fs pulses at 490 nm wavelength, generating laser powers in the terawatt range. The beam quality of the amplified pulses was within 1.3 times the diffraction limit, making possible focused intensities in the 1018 W/cm2 range.