24 43
Reference: Burley, J. D. & H. S. Johnston
           Ionic mechanisms for heterogeneous stratospheric reactions and
           ultraviolet absorption cross sections for NO2+, HNO3, and NO3- 
           in sulphuric acid,
           Geophys. Res. Lett. 13, 1359-1362, 1992.
   
NO3-(aq) + hv => NO2(aq) + O-(aq)      (i)

              -> NO2-(aq) + O(3P)(aq)  (ii)
 
Quantum yields: channel (i) 9.2e-3;  channel (ii) 1.1e-3  @ 305 nm
           Warneck, P., and C. Wurzinger
           Product quantum yields for the 305-nm photodecomposition
           of NO3- in aqueous solution,
           J. Phys. Chem 92, 6278-6283, 1988.
  
The absorption spectrum has two main peaks: at c. 200 nm and at 302 nm.

345-370 nm values extrapolated from 320-340 data by Julia Lee-Taylor, Feb'01
-----------------------------------------------------------------------------
lambda	sigma(20'C)  sigma(-20'C)
(nm)	(1E-20 cm2 mol-1)
-----------------------------------------------------------------------------
270	0.72	0.78	
275	0.99	1.12
280	1.33	1.48
285	1.72	1.92
290	2.13	2.34
295	2.49	2.70
300	2.70	2.88
305	2.68	2.80
310	2.38	2.42	
315	1.87	2.84
320	1.24	1.16
325	0.704	0.64
330	0.33	0.29
335	0.13	0.11
340	0.061	0.05
345	0.029	0.022
350	0.014	0.01
355	0.006	0.004
360	0.003	0.002