Abstract
Independent measurements of the absorption cross section of the IO radical for the A/sup 2/II-X/sup 2/II band system are reported. A value of (3.1 +- 0.6) x 10/sup -17/ cm/sup 2/ was observed for the (4,0) bandhead in good agreement with an earlier investigation. Results are also reported for the (5,0), (3,0), (2,0), and (1,0) bands over the wavelength range of 410-470 nm. However, no measurable (<2 x 10/sup -18/ cm/sup 2/) absorption was found for the (0,0) band. The atmospheric photodissociation rate constant, J/sub IO/, for solar zenith angles of 0/sup 0/-40/sup 0/ was calculated to have a value of 0.06 +- 0.01 s/sup -1/. This value is a factor of 5 lower than previous estimates. Finally, the rate coefficient for the reaction IO + IO ..-->.. products (3) has been measured at 760 Torr of N/sub 2/ and 300 K. The measured effective bimolecular rate constant was found to be (6.6 +- 2) x 10/sup -11/ cm/sup 3/ x molecule/sup -1/ x s/sup -1/, in good agreement with recent results by Sander (1986).
