Cavity ring-down spectroscopy (CRDS) is a simple, highly sensitive direct absorption technique based on the rate of absorption of light circulating in an optical cavity. CRDS can be used to study atoms and molecules in the gas and condensed phase, and is especially powerful for measuring strong absorptions of species present in trace amounts or weak absorptions of abundant species. The technique can be applied in physical, atmospheric, environmental and analytical chemistry, also combustion...
