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Kinetic spectroscopy studies of propyl and propylperoxy radicals

HIROYUKI ADACHI and NORMAN BASCO

Chemistry Department, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T I Y6 (Canada)

The flash photolysis of azo-n-propane and of azoisopropane was studied by kinetic spectroscopy. Transient absorption spectra in the region 220 - 260 nm were assigned to the n-propyl and isopropyl radicals. The extinction coefficients and the rate constants for the mutual reactions of both radicals were measured.

The rate constants for the dissociation of the vibrationally excited triplet state of the azopropanes into radicals were measured from the variation in the quantum yield of the radicals with pressure.

The spectra of the propylperoxy radical were characterized. Rate constants for the mutual interactions and for the reactions with NO and NO2 were mea- sured .

Photolysis of CH3CH0 in the range 250 - 330 nm

H. MEYRAHN, G.K. MOORTGAT and P. WARNECK

Max-Planck-Institutfiir Chemie, Saarstrasse 23, D-6500 Ma& (FAG.)

The photodecomposition of mixtures of 200 ppm CH,CHO in 1 atm of air or purified NZ were studied at 300 K, and the quantum yields p of CO and CH, were determined in the spectral range 250 - 330 nm. The quantum yields are nearly identical for both systems. qco increases monotonically from zero at 330 nm to almost 0.8 at 250 run. qcHq remains essentially zero for A Z 285 nm and then rises sharply to 0.45 at 250 nm. Quantum yields for both primary steps

CH&HO hv CHJ + CHO and

CH,CHO hv CH4 + CO

were derived and the results are compared with results from previous work. The measured production rates of CO in sunlit CH&HO-air and CHSCHO-N2 mix- tures produced photodissociation rates of about (2 - 3) x lo-6 s-l, in good agreement with calculated rates. This value is an order of magnitude lower than the currently accepted values of Weaver et al. [I].

1 J. Weaver, J. Meagher and J. Heicklen, J. Photvchem., 6 (1976 - 1977) 111.