Fig. 2.

Transient oxygen-edge absorption spectra of thymine. a Representative near-edge absorption fine structure (NEXAFS) spectra 2 ps after ultraviolet (UV) excitation and without UV excitation. UV-induced increase in intensity is marked red, UV-induced decrease is light blue. UV excitation leads to the appearance of a new spectral feature around 526.4 eV and a bleach of the ground state π* resonance at 531.4 eV. b False-color plot of time-dependent NEXAFS difference spectra (see color bar in the upper right corner). The UV-induced features at 526.4 and 531.4 eV are clearly visible throughout the positive pump-probe delays. c Time-dependence of the UV-induced features with fits based on a rate equation model. All error bars represent the standard error of mean