Figure shows a representative pump-probe spectrum for the two higher-energy peaks, at +511 and +984 cm -1 denoted with letter b in Fig , using the 193 nm ns probe. We could not perform pump-probe measurements for these peaks using the picosecond probe pulses at 213 nm, due to low signal-to-noise. The spectrum in Fig. , with its spike in the first 10 ns, corresponds to a combination of a very fast and a very slow decay. The fast decay has a lifetime equal to or smaller than the instrument response function (IRF) of approximately 10 ns. The slow channel can be fit with a single exponential decay with a lifetime of the order of 10 µs. Figures and show pump-probe spectra for the peak at +1307 cm -1 (denoted with letter c in Fig. ) with ns 193 nm and ps 213 nm probe pulses, respectively. The slow part of the nanosecond trace was fit with a monoexponential function just as in the case of the peaks denoted with letter b with a lifetime of the order of 10 µs. The picosecond probe pulse at 213 nm also allowed us to estimate the shorter-lived component with a lifetime of 1429 ps (Fig. ).