GAS DETECTION METHOD AND APPARATUS USING CHEMISORPTION AND/OR PHYSISORPTION

摘要

Gas Detection Method and Apparatus UsingChemisorption And/Or PhysisorptionAbstractGas species are detected with a capacitorhaving a solid, ionic dielectric excited by an ACvoltage in the range from 0.01-30 Hz, with an amplitudeof 1-100 millivolts to allow physisorption processesand/or with an AC voltage in the same frequency rangeand amplitudes from 0.01-3 volts to achievechemisorption reactions. The AC impedance of thecapacitor is detected for both physisorption andchemisorption excitation to determine gas species andconcentration. In chemisorption, diode like actionoccurs, and is detected by AC harmonic detectionprocesses. The surface of the dielectric on which thegas is: incident is overlaid with a grid or porouselectrode, fabricated of inert metal or a catalystwhich causes the capacitor to enable preferentialadsorption by the dielectric of certain materials, toindicate the presence of certain gases. Pluralcapacitors, having different adsorption characteristicsin response to different gases facilitates detection ofplural gases. The dielectric is a rare earth fluoride,preferably lanthanum fluoride. The AC impedance of thecapacitor provides the specie and concentrationindications.