22 research outputs found

    Instrumentation for fluorescence lifetime measurement using photon counting

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    We describe the evolution of HORIBA Jobin Yvon IBH Ltd, and its time-correlated single-photon counting (TCSPC) products, from university research beginnings through to its present place as a market leader in fluorescence lifetime spectroscopy. The company philosophy is to ensure leading-edge research capabilities continue to be incorporated into instruments in order to meet the needs of the diverse range of customer applications, which span a multitude of scientific and engineering disciplines. We illustrate some of the range of activities of a scientific instrument company in meeting this goal and highlight by way of an exemplar the performance of the versatile DeltaFlex instrument in measuring fluorescence lifetimes. This includes resolving fluorescence lifetimes down to 5 ps, as frequently observed in energy transfer, nanoparticle metrology with sub-nanometre resolution and measuring a fluorescence lifetime in as little as 60 μs for the study of transient species and kinetics

    Selective excitation of tryptophan fluorescence decay in proteins using a sub-nanosecond 295 nm light-emitting diode and time-correlated single-photon counting

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    We demonstrate an AlGaN light-emitting diode (LED) giving pulses of ~600 ps full width half maximum, 0.35 W average power, 0.6 mW peak power, and ~12 nm bandwidth at 295 nm. This source is ideal for protein intrinsic tryptophan fluorescence decay research without the unwanted excitation of tyrosine and paves the way to lab-on-a-chip protein assays using fluorescence decay times. Fluorescence decay and anisotropy decay measurements of human serum albumin are reported and the usefulness of the 295 nm LED demonstrated in comparisons with a nanosecond flashlamp and LEDs with nominal wavelength emission of 280 nm

    Excitation of fluorescence decay using a 265 nm pulsed light-emitting diode: Evidence for aqueous phenylalanine rotamers

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    The authors describe the characteristics and application of a 265 nm AlGaN light-emitting diode (LED) operated at 1 MHz repetition rate, 1.2 ns pulse duration, 1.32 mu W average power, 2.3 mW peak power, and similar to 12 nm bandwidth. The LED enables the fluorescence decay of weakly emitting phenylalanine to be measured routinely, even in dilute solution. For pH of 6-9.2, the authors find evidence for a biexponential rather than monoexponential decay, providing direct evidence for the presence of phenylalanine rotamers with a photophysics closer to the other two fluorescent amino acids tryrosine and tryptophan than has previously been reported. (c) 2006 American Institute of Physics
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