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New Light Sources for Time-Correlated Single Photon Counting in Commercially Available Spectrometers

Roger Fenske, Dirk U. Näther, Mark Goossens, S. Desmond Smith

The method of Time-Correlated Single Photon Counting (TCSPC) requires high repetitive light sources (>100 kHz) with pulse widths of ideally less than approximately 20 ps. While these light sources have been available for some time now in the form of Ti:Sapphire lasers, picosecond pulsed diode lasers (<90 ps) and light emitting diodes (<700 ps), they all have the drawback of either having no spectral tunability, or tunability over a very narrow spectral range (10 nm – 100 nm). While this is often sufficient for specific laboratory setups for measurements of fluorescence lifetimes, commercial Fluorescence Lifetime Spectrometers have suffered for a long time from the lack of the availability of simple, compact and relatively inexpensive broad spectral band light sources that can be employed for TCSPC. A new light source as an integral part of a commercial fluorescence lifetime spectrometer will be discussed that allows tunability over a wide spectral band of more than 500 nm.

The Supercontinuum Laser as a Flexible Source for Quasi-Steady State and Time-Resolved Fluorescence Studies

Roger Fenske, Dirk U. Näther, Richard B. Dennis, S. Desmond Smith

Commercial Fluorescence Lifetime Spectrometers have long suffered from the lack of a simple, compact and relatively inexpensive broad spectral band light source that can be flexibly employed for both quasi-steady state and time resolved measurements (using Time Correlated Single Photon Counting [TCSPC]). This paper reports the integration of an optically pumped photonic crystal fibre, supercontinuum source1 (Fianium model SC400PP) as a light source in Fluorescence Lifetime Spectrometers (Edinburgh Instruments FLS920 and Lifespec II), with single photon counting detectors (micro-channel plate photomultiplier and a near-infrared photomultiplier) covering the UV to NIR range. An innovative method of spectral selection of the supercontinuum source involving wedge interference filters is also discussed.