A compact quantum-cascade laser based spectrometer for monitoring the concentrations of methane and nitrous oxide in the troposphere

A spectrometer, based on the frequency down-chirped radiation from a pulsed quantum-cascade laser, capable of detecting fluctuations in local ground level methane and nitrous oxide concentrations over a time scale of minutes, is presented. The applicability of this instrument to low-level atmospheric detection is demonstrated through sampling gases in two locations.