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 (h nu (pump) + h nu (probe)) in common solvents for determination of the pump- probe cross-correlation function in transient absorption experiments. Ten d ifferent solvents, including water, lower alcohols, n-hexane, n-heptane, ac etonitrile, dichloromethane, chloroform and tetrachloromethane, were studie d with UV excitation and UV-visible probe pulses. We report on how the sign als 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. (C) 2001 Elsevier Science B.V. All righ ts reserved.