Abstract

Quantitative detection of atomic oxygen, an important species in combustion and atmospheric chemistry, can be accomplished using multiphoton techniques if the relevant cross sections are known. We have recently reported¹ absolute measurements of the two-photon absorption and excited state photoionization cross sections for O(³P) at 226 nm, the wavelength of the first allowed two-photon transition. Although two-photon transitions at shorter wavelengths are expected to have smaller cross sections,² coincidences with excimer laser lines could lead to enhanced detection sensitivity. To explore this possibility, we have used the techniques described In Ref. ¹ to measure the corresponding cross sections for the 4p³P_2,1,0 ← 2p³P₂ transition at 201 nm and for the 5p³P_2,1,0←2p³P₂ transition at 193 nm. Results are discussed critically and compared with ab initio calculations.² The application of similar techniques to the detection of fluorine atoms³ is also described.

© 1986 Optical Society of America