Sensitive <i>i</i> <i>n</i> <i>s</i> <i>i</i> <i>t</i> <i>u</i> trace-gas detection by photothermal deflection spectroscopy

Abstract

We present a sensitive (5ppb for ethylene, 10−7 cm−1) and simple photothermal scheme for the detection of trace gases and measuring weak absorption in gas-phase samples. We also demonstrate the feasibility of this scheme for performing in situ measurements in the absence of sample cells or containers, thus eliminating the drawbacks of sampling and sampling techniques. Factors limiting our detectivity are discussed, and a comparison to the thermal lens effect is made.