On the use of two-photon absorption for determination of femtosecond pump–probe cross-correlation functions

We have investigated the applicability of two-photon absorption signals (hνpump+hνprobe) in common solvents for determination of the pump–probe cross-correlation function in transient absorption experiments. Ten different solvents, including water, lower alcohols, n-hexane, n-heptane, acetonitrile, dichloromethane, chloroform and tetrachloromethane, were studied with UV excitation and UV-visible probe pulses. We report on how the signals are influenced by the relative polarization of the pump and probe beams, the excitation intensity and the detection bandwidth. Other contributions to the signals are also discussed.