| abstract |
A low concentration of a substance, e.g., ozone, in a fluid, usually ambient air, is detected and indicated by passing a sample of the fluid through a light-tight enclosure in reacting proximity to a material, e.g., Rhodamine B, which luminesces in the presence of the substance to be detected or a material which normally luminesces (e.g., magnesium oxinate in 3650 Angstrom black light) and is quenched in the presence of the substance to be detected (e.g., hydrogen fluoride). Photographic film is positioned in the enclosure to be exposed to the luminescent reaction of the reactant material and the reacting substance to be detected, whereby exposure of the film indicates presence of a luminescent reaction (including a quenching of luminescence), hence, pressure of the substance to be detected, and film density is a measure of the summation or integral of the amount of the substance present (integral of the light emitted from the luminescent reaction over the time period of exposure). |