Femtosecond Transient Absorption Spectroscopy

Ultrafast spectroscopy is an interdisciplinary area of research that spans various disciplines in chemistry and provides essential information on the mechanistic and kinetic details of chemical events that occur in the timescale of 10 femtoseconds to 100 picoseconds. The chemical events in these experiments are initiated by an ultrafast laser pulse (pump) and the photophysical and photochemical events are probed by another ultrafast laser probe pulse.


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Femtosecond Transient Absorption Spectrometer is  operational for carrying out transient absorption experiments. The CPA-2010 1 kHz Amplified Ti:Sapphire Laser System from Clark MXR provides 775, 387 and 258 nm laser pulses for excitation. The software developed by Ultrafast Systems is user friendly and allows the user to monitor the kinetics at different wavelengths and spectral evolution at different times during data acquistion.  ASCII files can be exported to ORIGIN or other platforms. The methodology of femtosecond laser flash photolysis is useful in characterizing singlet and triplet excited states, excited state energy transfer, inter- and intramolecular electron transfer reactions, charge transfer complexation and radical recombination in aqueous and nonaqueous solvents as well as in heterogeneous systems such as colloidal suspensions and thin films.

Excitation wavelength: 775, 387 and 258 nm, pulse width 150 fs, 1 kHz, 1 mJ/pulse  @ 775 nm.

Detection Range
for Absorption:  420-750 nm   (Will be extended to IR when the detection system becomes available from Ultrafast Systems)

Detection Limit:
Delta Abs of  ~0.0005

Delay Times.:
Upto 1.6 ns with delay increments of 10 fs or greater. Each delay setting averages 2500 shots in 5 seconds (collection time can be reduced for faster aquistion).  The delay times can be varied during the experiment to cover both short and long times in a single experiment. 
Sample Cell: Currently employs a 1 or 2 mm cuvette (static or flow mode). Less than 1 ml of sample is sufficient, if it is stable under laser excitation.Tracking the absorption using reverse delay allows one to check the stability of the sample and the accuracy of detection.