  We introduce a new scheme for generating short-wavelength coherent broadband
radiation with well-controlled spectral characteristics. It is based on shaping
long-wavelength femtosecond pulse to coherently control atomic
resonance-mediated (2+1) three-photon excitation to a broad far-from-resonance
continuum. Here, the spectrum (central frequency and bandwidth) of
deep-ultraviolet coherent broadband radiation generated in Na vapor is
experimentally controlled by tuning the linear chirp we apply to the driving
phase-shaped near-infrared femtosecond pulse. This is a first step in
implementing the full scheme for producing shaped femtosecond pulses at
wavelengths down-to the vacuum-ultraviolet range.
