O(D-1) produced from O-2 by photodissociation in the Schumann-Runge continuum was studied. The metastable atom O(D-1) was detected by observing the 762 nm fluorescence from O-2(b (1) Sigma(g)(+)) generated by the energy transfer process O(D-1) + O-2 --> O + O-2(b (1) Sigma(g)(+)). A quantum yield of unity was found in the wavelength range 139-175 nm. O(D-1) was detected at wavelengths longer than the threshold at 175 nm with reduced quantum yields due to excitations of molecules in the high rotational states. The quantum yields vary from 1 in the range 130-139 nm, resulting from crossing of the state (3) Sigma(u)(-) with (3) Pi(u). The absorption spectra for both states were determined. The peaks for maxima and minima absorptions were compared with previous experimental and theoretical results.
