Transient absorption (TA) spectroscopy was performed using a custom-built setup in standard transmission geometry with nearvertical incidence of pump and probe light. The used setup was pumped by a commercial Ti:sapphire laser system (Coherent Inc., Legend Elite Duo), delivering pulses of 25 fs duration at 800 nm central wavelength and 2.5 mJ pulse energy with a repetition rate of 5 kHz. Pump-light generation: Visible excitation light centred at 400 nm (3.1 eV) was generated by frequency doubling about 0.2 mJ of the fundamental pulse with a BBO crystal. Deep-UV (DUV) pump pulses centred at 225 nm (5.5 eV) were generated by sum-frequency mixing of 400 nm and 514 nm pulses, respectively. The latter were obtained using the output of an optical-parametric amplifier (OPA, Coherent Inc., OPerA Solo). The maximum energy of the pump beam at the sample position was about 0.2 J per pulse for the DUV light, and about 8 J for the visible light. In each case, the excitation spot had a 1/e 2 diameter of about 600 m, resulting in a radiant exposure of about 70 J cm -2 (DUV) and 2.8 mJcm -2 (VIS), respectively. Keeping in mind the respective photon energies of the VIS and DUV pulses, the actual photon number density per unit area is about 70 times higher under visible light excitation.