Femtosecond pump-probe spectrometer

The client's brief was to upgrade the EOS nanosecond TA spectrometer (installed in 2017) to a femtosecond spectrometer. After the upgrade, the spectrometer had to be able to measure transient absorption from at least 360 nm to 1600 nm and achieve femtosecond temporal resolution. In addition to liquid samples in cuvettes, the spectrometer also had to be able to measure transparent and non-transparent solid samples.

We complemented the EOS nanosecond spectrometer with the HELIOS FIRE femtosecond system. The probe beam was guided into a new high-speed optical delay path (8 ns time window, 14 fs resolution) and then directed at nonlinear crystals for UV, VIS and NIR supercontinuum generation. Femtosecond pulses exiting the optical parametric amplifier (tunable range 320-1300 nm) were used for excitation. The spectrometer was further complemented by a motorized holder for the measurement of transparent solid-state samples and a module for the measurement of non-transparent samples in the reflective mode. The extended spectrometer can cover the time scale from microseconds to femtoseconds and allows the recording of transient absorption from 350 nm to 1600 nm.