Transient Absorption, aka pump-probe, is a widely used time-resolved spectrometry technique based on detecting photoinduced absorption changes in the sample. This method is used in photochemistry and photophysics to study excited state dynamics of various materials and molecules. Transient absorption measurements are based on the absorption registration after a laser pulse (pump) excites the sample. By varying the arrival time of the second (probe) pulse with respect to the first pulse, you can measure how absorption changes over time after the excitation.

Ultrafast Systems’ transient absorption spectrometers allow to monitor photo-induced absorption changes without any gaps in coverage from UV to mid-IR over time windows from picoseconds to microseconds and beyond.
In time-resolved fluorescence spectrometry, the molecules are excited using a laser pulse and their fluorescence is recorded as a function of time. The two most popular experimental techniques for measuring fast fluorescence decays are Time-Correlated Single Photon Counting (TCSPC) and Fluorescence Upconversion. In TCSPC, fast single photon detectors and electronic timing boards are used to measure fluorescence lifetimes with picosecond time resolution.

The Fluorescence Upconversion technique allows to measure lifetimes with femtosecond time resolution by utilizing optical gating in nonlinear crystals with femtosecond laser pulses.

The HALCYONE spectrometers are capable of measuring time-resolved fluorescence across a broad spectral range, from UV to IR, and over a time window from picoseconds to microseconds.


KRONOS is a portable flash photolysis spectrometer designed for transient absorption and emission measurements on the microsecond and longer time scales. It is intended as a chemical kinetics experiment in university or high school teaching laboratories.

KRONOS can measure solid and liquid samples in absorption as well as emission modes. It utilizes a Xe arc flash lamp with bandpass filters as an excitation source.

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