SUBMILLISECOND RESPONSE-TIMES OF OXYGEN-QUENCHED LUMINESCENT COATINGS

An apparatus and data analysis methodology is described which allows d etermination of response time to oxygen concentration changes of lumin escent oxygen sensor coatings. Utilizing a solenoid valve, a sample ch amber creates a pressure jump from 0.1 to 700 Torr in 600 mus that is followed by 15 ms of ringing. An optical detection system measures the response of porphyrin-based luminescent oxygen sensors to the pressur e jump. The pressure in the chamber is measured simultaneously and ind ependently with a piezoresistive pressure transducer. Data analysis te chniques using nonlinear least-squares and numerical convolution of th e luminescent response to the pressure rise allow determination of res ponse times of the oxygen sensor. The response to pressure jumps of se veral luminescent oxygen sensitive coatings designed for video lumines cent barometry are measured with this computer-controlled instrument. Several coatings were studied with response times of approximately 2.5 s, approximately 400 ms, 11 ms, 1.5 ms, and <25 mus. Studies of the s ystem suggest that we can determine response times down to about 10 mu s.