Small-size resonant photoacoustic cell with reduced window background for laser detection of gases

Abstract

A photoacoustic resonant cell with the inner volume is ∼0.5 cm3 is presented. The shape of the cell cavity is chosen such as to minimize a background signal arising due to the absorption of laser beam in the cell windows. The experimental setup, the measurement procedure, and the design of the cell are described. The results of detecting ammonia in a nitrogen flow using the R(30) oscillating line of a CO2 laser are represented. The minimal detectable absorption achieved in experiment is ∼3.2 × 10−8 cm−1 W Hz−1/2.