Photoacoustic effect induced by negative luminescence device

摘要

The cantilever enhanced photoacoustic trace gas detection technique has been combined with mid-infrared light emitting diodes (LEDs) producing significant negative luminescence at a reverse bias. In contrast to normal positive photoacoustic phenomenon the negative luminescence of the LED creates wavelength specific cooling of the gas under study and pressure drop in the photoacoustic sample cell, which can be detected by a cantilever microphone. In experiments a LED operating at 5.5 μm wavelength range was used to detect acetone vapor.