| Popis: |
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 4p3P2,1,0 ← 2p3P2 transition at 201 nm and for the 5p3P2,1,0←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. |
