< 4 ps Time-Resolved Fluorescence Spectroscopy
04 Feb 2010
Yes
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The experimental set-up developed for Kerr-gated resonance Raman spectroscopy can also be employed to record fluorescence spectra with < 4 ps time resolution.

The Kerr-gate is simply a fast (< 4 ps) optical gate; by controlling the point at which the gate opens slices in time through the fluorescence of a sample can be recorded.

The useful transmission range of the CS2 Kerr gate is 390-700 nm with the lower limit being set by the electronic absorption of CS2 and the upper limit set by background due to stimulated anti-Stokes emission in the medium induced by the 800 nm gating pulse.  The UV coverage can be extended down to 300 nm using benzene in place of CS2.

clf_ultra_time_resolved_fluorescence_550px.jpg​Note: This technique cannot be employed to study naturally long lived luminescence states as the flux in 4 ps is too weak to be detected. For this an intensified charge-coupled device (ICCD) would be employed. This is an electrical rather than optical gate and hence has a longer open time.​

Schematic of the Ultra Kerr-gated fluorescence setup.  The red beam is the 800 nm output from the titanium-sapphire laser which is used to drive the tunable OPA and the Kerr-gate.  The blue beam is the pump beam and the dashed grean line represents the fluorescence from the sample.​

Contact: Towrie, Mike (STFC,RAL,CLF)