HYBRID GAS DETECTOR OF SQUARYLIUM DYE LANGMUIR-BLODGETT-FILM DEPOSITED ON A QUARTZ OSCILLATOR

A hybrid gas detector combined optical detector with a weighing system for adsorbed gas in Langmuir-Blodgett films deposited on a quartz oscillator is reported. With this detector, the fluorescence intensity change from a squarylium dye LB film containing J-aggregates and the amount of adsorbed gas in the dye LB film are measured simultaneously. Responses of this detector for NO2, trichloroethylene, NH3 were evaluated. On exposure to NO2, the fluorescence was sharply quenched in correspondence with a decrement of oscillation frequency. The ratio of fluorescence quenching to the amount of adsorbed NO2 gas molecules was estimated with two different signals from this hybrid gas detector. On the other hand, a slight increment of fluorescence was observed with a decrement of oscillation frequency after introduction of NH3 gas. In the case of an organic solvent such as trichloroethylene, a decrement of oscillation frequency was observed without change of fluorescence intensity.