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Time-resolved fluorescence

Our time-resolved fluroescence instrument is setup for performing both UV and VIS fluorescense experiments.  Our excitation source consists of a Ti:Sapphire laser (Verdi V10 pumped Mira 900D) with a pulse picker and harmonic generation optics.  The excitation source is shown here:


The sample compartment is a 4-position thermoelectrically temperature controlled turret from Quantum Northwest.  This unit also has a built in stirrer which makes it great for automated titrations.  Our detection consists of typically two PMH100 PMT's from Becker-Hickl with computer controlled polarizers in the path for anisotropy measurements.  We have the option of using a Hamamatsu microchannel plate in cases where we need to bring the time resolution below 50 ps. 

The TCSPC experiment is typically run using 3 programs: The TCSPC acquisition program from Becker-Hickl (shown on the right, below), the sample controller (shown in the middle, below) and the titration program (shown on the left, below).  One could run everything manually, too, of course.  The sample controller operates the 4-position turret position, controls temperature, moves the polarizers, logs the laser power and scans/moves the monochromator if it is being used in the experiment.  The titration program controls the Hamilton Microlab 500 series titrators to perform two identical titrations quasi-simultaneously.  This is very handy for FRET experiments where one typically wants to do a donor-only control under the same conditions as close in time as possible to the DA-labeled sample. 
 


The data analysis is typically done using Savuka and its associated utilities.

Kinetic experiments can be performed using either a Biologic stopped-flow with an umbilical to replace the QNW turret or with the continuous-flow microsecond mixer when folding time resolution faster than a ms are needed.

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