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Pump probe transient absorption/reflection spectroscopy setup
An ultrafast femtosecond excitation is provided by a Coherent RegA 9000 regenerative amplifier operating at 250 kHz seeded by a Coherent Vitara mode locked Ti:Sapphire oscillator. The laser emission is tuned to the desired energy via a Coherent OPA 9400 optical parametric amplifier. The optical setup is used to split the laser radiation into a stronger beam (pump) used to excite the carriers in the sample, and a weaker beam (probe) used to monitor the pump-induced changes in the optical constants of the sample such as transmission or reflectivity. A detection scheme using two balanced detectors in combination with a SR865S Lock-in Amplifier is employed to measure very small changes in the optical properties of the material as a function of the time delay between pump and probe. Measuring the changes in the optical constants as a function of time delay between the arrival of pump and probe pulses yields information about the relaxation of electronic states in the sample.
The Pump-Probe spectroscopy is therefore a powerful two-photon technique used to study ultrafast relaxation dynamics of carriers in novel materials and structures.
Excitation Tunability: wavelength range from 400 to 1500 nm
Optical Power: up to 50 mW (200 nJ per pulse)
Temperature Tunability: 8 K to RT
Time Resolution: femtosecond resolution thanks to <100 fs pulse width and 250 kHz repetition rate
Measurement Flexibility: both reflection and transmission options for opaque and transparent samples
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