Femtosecond single-pulsed supercontinua (SC) are produced in a short sub-cm piece of photonic crystal fiber. The SC span from 450 nm to more than 1.1 mum with 1-nJ energy injection. UV light down to 340 nm is observed with increased injection power. Using such a single-pulsed SC we implemented a compact transient absorption spectrometer with broadband detection and 150-fs FWHM time resolution to monitor the ultrafast dynamics of the electronic states of malachite green in ethanol excited to the S(2) state. The full spectral evolution is observed from 450 nm to 1050 nm, with high sensitivity and a signal-to-noise ratio as high as 1000.