A fast opening mechanical shutter system for flash photolysis experiments

A rotating disk mechanical shutter system has been developed to trigger flash photolysis experiments and prevent scattered light from blinding photomultipliers mounted on a monochromator. Trigger pulses are provided by He/Ne laser light passing through a pinhole in the disk. The monochromator entrance slit is exposed after a variable delay time by a slot in the disk. The system provides fast slit opening times (a few μsec), μsec jitter in delay times, and very high discrimination against unwanted light (rejecting unwanted signals ∼104 times the desired signal). The system is ideal for flash or laser photolysis experiments which must utilize very weak line sources as kinetic probes.