Flash Photolysis :
When monitoring fast kinetic changes using microfluorescence or electrophysiology it is often important to avoid the time lag and mixing artefacts associated with conventional perfusion systems or the direct application of reagents. One useful approach is to introduce protected "caged" reagents in advance and then to photolytically release them using a brief and intense UV flash. This offers the combined benefits of near-instantaneous introduction of compounds, improved homogeneity and easy synchronisation with recording equipment.
The key elements of a flash photolysis system are described below:
Illumination source :
The energy required to cleave caged compounds is usually provided by a xenon arc flash lamp or a UV laser. In both cases the the source should be capable of producing highly energetic pulses in the region of 1 msec in duration and must have the facility to be externally triggered using a TTL trigger pulse. The light source would typically be optically filtered with a broadband UV transmitting filter.
