The Picarro G2401-mc utillzes wavelength scanned cavity ring down spectroscopy, a technique wherein the exponential decay of optical extinction within a resonant cavity is modified by molecular absorption. This decay time is called a ring-down time. Over a specific wavelength range, ring-down times are proportional to the concentration of the absorbing species. The figure below shows a schematic of the instrument design on the left and typical time series traces on the right.
