ULTRA LOW ABSORBANCE KINETIC PHOTOMETER

ONE KEY PROBLEM IN MAKING LOW ABSORBANCE MEASUREMENTS IS THERANDOM NOISE GENERATED IN VARIOUS SYSTEM COMPONENTS SUCH AS PHOTODETECTORS, ETC. ANOTHER CLASS OF PROBLEMS ARE ENVIRONMENTAL IN ORIGIN, SUCH AS AIRBORNE OR SAMPLE-BORNE CONTAMINATION, AND SCHLIEREN EFFECTS. THE PROPOSED INSTRUMENT, BASED ON WELL KNOWN WAVELENGTH MODULATION TECHNIQUES, BUT NOVEL IN CERTAIN CRITICAL ASPECTS, SUBSTANTIALLY REDUCES THE IMPACT OF THESE ERROR SOURCES. IT IS ESTIMATED THAT IT WILL ACCURATELY MEASURE KINETIC ABSORBANCE CHANGES AS LOW AS ONE MICROABSORBANCE UNIT PER SECOND WITHIN 100 SECONDS. THIS REPRESENTS SEVERALORDERS OF MAGNITUDE IMPROVEMENT OVER CURRENT INSTRUMENTS. DURING PHASE I THE KEY CONCEPTUAL FEATURES OF THE INSTRUMENT WILL BE TESTED, BOTH BY FURTHER MATHEMATICAL MODELING AND ALSO EXPERIMENTALLY. A BREAD-BOARD INSTRUMENT USING COMMERCIALLY AVAILABLE COMPONENTS WILL BE SUBJECTED TOACCURACY, SENSITIVITY AND STABILITY TESTS.