Detection of atomic oxygen by intracavity spectroscopy.

Atomic oxygen generated in a discharge flow tube is detected at 630.03 and 636.38 nm using intracavity dye-laser spectroscopy. This is the first reported observation of these highly forbidden transitions in absorption. It is demonstrated that absolute concentration measurements can be made with intracavity spectroscopy. The intracavity sensitivity relative to that of conventional absorption spectroscopy is enhanced by factors ranging from 3500 to 17,000, depending on the laser power. At the highest sensitivity, atomic oxygen should be detectable in a 5-cm path length at densities of 10(15)-10(16)/cm(3).