DUAL-BEAM SPECTROMETER FOR OPTICAL STUDIES OF SPREAD MONOLAYERS AT THE AIR-WATER-INTERFACE

An optical spectrometer for the study of low level optical absorption and reflection of spread monolayers at the air-water interface is described. This spectrometer is suitable for measurements at wavelengths from similar to 350 to 800 nm and has a precision of similar to 2x10(-5) in terms of effective optical density. It employs a dual beam design utilizing fiber optic bundles to guide light and a multichannel photodiode array detection system. Instrumental control and data gathering are designed within Labwindows software. Representative spectral absorption data from chlorophyI1 a degradation kinetics are presented by way of illustration. Comparison of chlorophyll a reflection and absorption is also given.