Transient absorption experimental set-up with femtosecond time resolution. Femto- and picosecond study of DCM molecule in cyclohexane and methanol solution

Abstract

The experimental set-up for time dependent transient absorption/gain measurements with femtosecond time resolution is presented. Using pump-probe spectroscopy technique with femtosecond pulses from Ti:Sapphire laser system (Spectra Physics), the optical density of transient absorption and transient gain in the spectral range of 330–700nm, time resolution of 120fs, can be measured with the precision of up to 0.005. Knowing the real time resolution and “zero time” dispersion of the system from two-photon absorption measurements, we performed femto- and picosecond study of electronically excited DCM molecule in c-C6H12 and MeOH solution. The emission decay of the DCM molecule in the locally excited singlet state, S1-LE, was measured with picosecond time resolution using TCSPC set-up (Time Correlated Single Photon Counting). The steady-state and time resolved measurements permitted the determination of the properties of this locally excited singlet S1-LE state and the pathways of its deactivation.