54 33
Reference: JPL Publication 94-26
           Chemical Kinetics and Photochemical Data for Use in Stratospheric
           Modeling
           Evaluation Number 11
           December 15, 1994
           page 118

H2O2 + hv -> OH + OH

"The recommended 298 K absorption cross section values, listed in Table 11, are 
the mean of the data of Lin et al. [978], Molina and Molina [1102], Nicovich
and Wine [1171], and Vaghjiani and Ravishankara [1600].  Molina and Molina
[1102] supersedes the earlier results of Molina et al. [1108].  Nicovich and
Wine measured the cross sections at lambda +- 230 relative to the values at
202.6, sigma = 4.32 x 1E-19 cm^2, and at 228.8 nm, sigma = 1.86 x 1E-19 cm^2.
The values are within 2% of the recommended value.

Nicovich and Wine have measured the temperature dependence of these cross
sections.  They expressed the measured cross sections as the sum of two
components;  sigma1, due to absorption from H2O2 which has the O-O stretch
excited and the other sigma0, due to absorption by ground state molecules.  For
atmospheric calculations the expression given in Table 12 may be used.  The
photodissociation quantum yield is believed to be unity.  At and above 248 nm,
the major photodissociation process is that leading to OH, i.e., the quantum
yield for OH production is 2 (Vaghjiani and Racishankara [1601] and Vaghjiani
et al. [1604]).  At 193 nm this quantum yeild decreases to about 1.5 (Vaghjiani
et al. [1604]; Schiffman et al. [1384]), and the quantum yield for O-atom
production increases to about 0.16 (Vaghjiani et al. [1604]).

Table 12:  Mathematical Expression for Absorption Cross Sections of H2O2
           as a Function of Temperature
---------------------------------------------------------------------------

 10^21 * s(l,T) = chi * sum(n=0,7){A(n) l^n} + (1-chi) * sum(n=0,4){B(n)l^n}

   Where T: temperature K;  l: nm;  chi = [1 + exp(-1265/T)]^(-1)
         s: cross section in cm^2

A(0) = 6.4761E-04            B(0) = 6.8123E+03
A(1) = -9.2170972E+02        B(1) = -5.1351E+01
A(2) = 4.535649              B(2) = 1.1522E-01
A(3) = -4.4589016E-03        B(3) = -3.0493E-05
A(4) = -4.035101E-05         B(4) = -1.0924E-07
A(5) = 1.6878206E-07
A(6) = -2.652014E-10
A(7) = 1.5534675E-13

Range 260-350 nm; 200-400 K

---------------------------------------------------------------------------"

Wavelength (nm)     Cross Section (cm^2 at 298K)
190			67.2
195			56.4
200			47.5
205			40.8
210			35.7
215			30.7
220			25.8
225			21.7
230			18.2
235			15.0
240			12.4
245			10.2
250			8.3
255			6.7
260			5.3
265			4.2
270			3.3
275			2.6
280			2.0
285			1.5
290			1.2
295			0.90
300			0.68
305			0.51
310			0.39
315			0.29
320			0.22
325			0.16
330			0.13
335			0.10
340			0.07
345			0.05
350			0.04