From JPL 2002:
CLOOCl + hv -> Cl + ClOO. Recommended absorption cross sections in the wavelength range 190-450 nm for
ClOOCl are listed in Table 4-29. The values for the wavelength range 200-360 nm are the average of
experimental results reported by Cox and Hayman [90], DeMore and Tschuikow-Roux [107], Permien et al.
[313], and Burkholder et al. [53]. For the 190-200-nm range the data are from DeMore and Tschuikow-Roux
[107], these being the only data available in that range. Data at wavelengths greater than 360 nm were obtained
from a linear extrapolation of the logarithm of the cross sections, using the expression
log(10**20 sigma(cm2)) = -0.01915 x lambda(nm) + 7.589. For lambda > 360 nm the extrapolated data are considered to be more
reliable than the experimental measurements because of the very small dimer cross sections in this region.
While the results of Cox and Hayman, DeMore and Tschuikow-Roux, Permien et al., and Burkholder et al. are
in good agreement at wavelengths below 250 nm, there are significant discrepancies at longer wavelengths,
which may be attributed to uncertainties in the spectral subtraction of impurities such as Cl2O, Cl2, and Cl2O2.
Huder and DeMore [167] measured ClOOCl cross sections over the 190-310-nm range using a method that
minimized the corrections required for impurities such as Cl2O. The cross sections from this study are
significantly smaller (up to a factor of 2) than the current recommendation, particularly when extrapolated
beyond 400 nm. Additional measurements are needed, particularly at the longer wavelengths, to check the
results of Huder and DeMore.
These studies also indicate that only one stable species is produced in the recombination reaction of ClO with
itself, and that this species is dichlorine peroxide, ClOOCl, rather than ClOClO. Using submillimeter wave
spectroscopy, Birk et al. [34] have further established the structure of the recombination product to be ClOOCl.
These observations are in agreement with the results of quantum mechanical calculations (McGrath et al.
[254,255]; Jensen and Odershede [184]; Stanton et al. [387]).
Table 4-29. Absorption Cross Sections of ClOOCl at 200-250 K
Wavelength, nm
	Xsection, 10**-20 cm2
190	565
192	526
194	489
196	450
198	413
200	383.5
202	352.9
204	325.3
206	298.6
208	274.6
210	251.3
212	231.7
214	217
216	207.6
218	206.1
220	212.1
222	227.1
224	249.4
226	280.2
228	319.5
230	365
232	415.4
234	467.5
236	517.5
238	563
240	600.3
242	625.7
244	639.4
246	642.6
248	631.5
250	609.3
252	580.1
254	544.5
256	505.4
258	463.1
260	422
262	381.4
264	344.6
266	311.6
268	283.3
270	258.4
272	237.3
274	218.3
276	201.6
278	186.4
280	172.5
282	159.6
284	147.3
286	136.1
288	125.2
290	114.6
292	104.6
294	95.4
296	87.1
298	79
300	72.2
302	65.8
304	59.9
306	54.1
308	48.6
310	43.3
312	38.5
314	34.6
316	30.7
318	28
320	25.6
322	23.4
324	21.4
326	19.2
328	17.8
330	16.7
332	15.6
334	14.4
336	13.3
338	13.1
340	12.1
342	11.5
344	10.9
346	10.1
348	9
350	8.2
352	7.9
354	6.8
356	6.1
358	5.8
360	5.5
362	4.5
364	4.1
366	3.8
368	3.5
370	3.2
372	2.9
374	2.7
376	2.4
378	2.2
380	2.1
382	1.9
384	1.7
386	1.6
388	1.4
390	1.3
392	1.2
394	1.1
396	1
398	0.92
400	0.85
402	0.78
404	0.71
406	0.65
408	0.6
410	0.54
412	0.5
414	0.46
416	0.42
418	0.38
420	0.35
422	0.32
424	0.29
426	0.27
428	0.25
430	0.23
432	0.21
434	0.19
436	0.17
438	0.16
440	0.15
442	0.13
444	0.12
446	0.11
448	0.1
450	0.09