Fig. 2: Pump-probe transients on or near the 1s–2p± transition for different laser intensities.

The transient transmission change of the probe due to the pump pulse, ΔT is shown vs. t. They have been normalized to their global maximum and offset vertically. a Pump pulse energy (Ep) dependence on resonance (at laser photon energy ħω = 39.2 meV) for natSi:P. The solid line is an exponential decay fit. b As in a but off-resonance at ħω = 38.6 meV. c Dependence of the transients on photon energy (ħω) at a fixed pulse energy of Ep = 0.11 μJ. The solid lines are fits with Eq. (3) as described in the text.