34 23
Reference: JPL Publication 94-26
           Chemical Kinetics and Photochemical Data for Use in Stratospheric
           Modeling
           Evaluation Number 11
           December 15, 1994
           page 130 ff.

CH2O + hv -> H + HCO  (Phi1)
          -> H2 + CO  (Phi2)

"The quantum yields have been reported with good agreement by Horowitz and
Calvert [691], Clark et al. [307], Tang et al. [1535], Moortgat and Warneck
[1127], and Moortgat et al. [1121, 1224].  The recommended values listed in
Table 22 are based on the results of these investigators, as evaluated by S.
Madronich (private communication, 1991).  The quantum yield for the production
of H2 and CO is pressure and temperature dependent for wavelengths longer than
about 330 nm (Morrtgat et al. [1124]).  Table 22 gives the values at
atmospheric pressure and room temperature;  the reader is referred to the
Moortgat et al. publication for information on values at lower pressures and
temperatures."

Table 22.  Absorption Cross Sections and Quantum Yields for Photolysis of CH2O

Note:  The values are averaged for 2.5 nm intervals centered on the indicated
wavelength.

* Cross sections for -50 C < T < 20 C calculated as sigma(T) = A + Bx1E-3xT

===============================================================================
lambda 		 Phi1   	  Phi2
(nm)		(H+HCO) 	(H2+CO)
===============================================================================
301.25		0.749		0.251
303.75		0.753		0.247
306.25		0.753		0.247
308.75		0.748		0.252
311.25		0.739		0.261
313.75		0.724		0.276
316.25		0.684		0.316
318.75		0.623		0.368
321.25		0.559		0.423
323.75		0.492		0.480
326.25		0.420		0.550
328.75		0.343		0.634
331.25		0.259		0.697
333.75		0.168		0.739
336.25		0.093		0.728
338.75		0.033		0.667
341.25		0.003		0.602
343.75		0.001		0.535
346.25		0.000		0.469
348.75		0.000		0.405
351.25		0.000		0.337
353.75		0.000		0.265
356.25		0.000		0.197