- Using diode-laser-based diagnostics, O/sub 2/(/sup 1//spl Delta/) yield and water vapor fraction were measured at the exit of a jet-type singlet oxygen generator (JSOG) for a chemical oxygen-iodine laser (COIL). Chlorine utilization and gas temperature at the generator exit were also measured, simultaneously. For conditions corresponding to the maximum chemical efficiency of the supersonic COIL energized by the JSOG, the O/sub 2/(/sup 1//spl Delta/) yield, water vapor fraction, chlorine utilization, and temperature at the generator exit are 0.65, 0.08 and 0.92, and 30/spl deg/C, respectively. Increase of the basic hydrogen peroxide temperature results in an increase of the water vapor fraction caused by an increase of the saturated water vapor pressure in the generator. As the pressure in the generator rises from 18 to 60 torr, the yield decreases from 0.65 to O.48. Dependence of the yield on the generator pressure is consistent with a rate constant for the O/sub 2/(/sup 1//spl Delta/) energy pooling reaction of 2.7/spl times/10/sup -17/ cm/sup 3//spl middot/S/sup -1/. The same rate constant explains the measured variation of the temperature along the flow in the diagnostic cell.