  Dispersive Fourier transformation is a powerful technique in which spectral
information is mapped into the time domain using chromatic dispersion. It
replaces a spectrometer with an electronic digitizer, and enables real-time
spectroscopy. The fundamental problem in this technique is the trade-off
between the detection sensitivity and spectral resolution, a limitation set by
the digitizer's bandwidth. This predicament is caused by the power loss
associated with optical dispersion. We overcome this limitation using Raman
amplified spectrum-to-time transformation. An extraordinary loss-less -11.76
ns/nm dispersive device is used to demonstrate single-shot gas absorption
spectroscopy with 950 MHz resolution--a record in real-time spectroscopy.
