Dr. Dean Atkinson adjusts a cavity mirror in a flash photolysis reactor that uses CRDS detection.

Dean is now a professor at Portland State University.

View of the Gas-phase Cavity Ring-down Flash-Photolysis Reactor

Visible Features:

• The reactor and cavity comprise the long tube pictured. At each end the mirror is mounted on vacuum flanges. Bellows couple these flanges to stainless tubes. The flange is mounted in an optical mount permitting cavity alignment.
• Inert gas flushes the stainless tubes and protects the mirrors from degradation.
• The center section of the cavity is constructed of 16 mm ID quartz tubing and the reaction mixture is flowed through that section. Flows are adjusted to minimize mixing between the flush and reaction mixtures. We have verified the stable (non-mixing) operational ranges for flows by reproducing absorption cross-sections of Cl₂.
• The 308 nm photolysis laser (orange box) initiates the reaction sequence by photolyzing a well-defined zone in the middle of the quartz tube.
• The side-window photomultiplier (lower left) has only five amplification stages wired so that it has a rise-time of < 1 nanosecond. The next web page shows the performance this cavity.