SUPPORTING INFORMATION Production of molecular iodine and triiodide in the frozen solution of iodide: implication for polar atmosphere Kitae Kim,, Akihiro Yabushita,, Masanori Okumura, Alfonso Saiz-Lopez, Carlos A. Cuevas, Christopher S. Blaszczak-Boxe, # Dae Wi Min, Ho-Il Yoon, Wonyong Choi,* School of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Korea Korea Polar Research Institute (KOPRI), Incheon 406-840, Korea Department of Molecular Engineering, Kyoto University, Kyoto 615-8510, Japan Department of Molecular and Material Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan Atmospheric Chemistry and Climate Group, Institute of Physical Chemistry Rocasolano, CSIC, Madrid, Spain # Department of Physical, Environmental and Computer Sciences Medgar Evers College-City, University of New York, Brooklyn, NY 11235, USA * To whom correspondence should be addressed. E-mail: wchoi@postech.edu; Fax: +82-54-279-8299
Dye laser Nd 3+ :YAG laser fluorescence lamp Valve HRM NaI ice Valve HRM PMT detector Coolant outlet Coolant inlet Figure S1. Schematic diagram of the experimental setup of a photochemical reactor cell coupled with CRDS. HRM and PMT stand for high reflective mirror and photomultiplier tube, respectively.
1.0 0.8 log r = 0.455 log [ H + ] 0 + 1.2982 0.6 0.4 log r 0.2 0.0 log r = 1.12 log [ I - ] 0 + 0.2977-0.2-0.4 log r = 1.42 log [ O 2 ] 0 + 4.4220-0.6-0.8-3.5-3.0-2.5-2.0-1.5-1.0-0.5 log [ H + ] 0-0.4-0.3-0.2-0.1 0.0 log [ I - 0.1 0.2 0.3 0.4 ] 0-3.8-3.6-3.4-3.2-3.0-2.8 log [ O 2 ] 0 Figure S2. The rate law determination of reaction 1. The slope of the plot of (log r) vs. log [conc.] determines the order for each reactant. That is, the order for [H + ] is determined to be 0.5 and that for [I - ] and [O 2 ] is determined to be 1.0 and 1.5, respectively. Therefore, the following rate law is derived: d[i 3 ] (mol L 1 s 1 ) = r = 2.16 10 2 [I ] 1 [O dt 2 ] 1.5 [H + ] 0.5
50 40 Aq Ice [I 3 - ] ( M) 30 20 10 0 25 o C -10 o C -20 o C -30 o C Figure S3. Iodide photooxidation to triiodide at different temperature. Experimental conditions: [I - ] 0 = 1 mm, after 2 h UV irradiation, ph = 3
0.4 80 Abs. 0.3 0.2 0.1 [I - ] = 0.1 M (air) [I - ] = 0.1 M (O 2 ) Transmittance of Pyrex filter 60 40 20 Transmittance 0.0 0 250 300 350 400 450 Wavelength (nm) Figure S4. UV-visible absorption spectrum of CT complex (I O 2 ) in pure oxygen-saturated aqueous solution. The transmittance of the pyrex filter employed for photoexperiments was also shown (red solid line) for comparison.
Figure S5. Model simulations of the experimental results. Utilizing CON-AIR to exemplify the release of I 2 (g) at initial I - concentrations relevant to Antarctica. We have therefore conducted a modelling exercise to reproduce the range of I 2 production in the CDRS reactor for the range of [I - ] o = 1 to 10 M used in the experiments. The irradiation conditions used in the model are typical of surface irradiances at 75 South during the austral springtime. 28 The modelled I 2 concentrations are in blue circles. Then, we extrapolated to environmentally relevant 43 concentrations [I - ] o = 10 nm (highlighted in sky blue in the inset) using a line of best linear fit (r 2 = 0.989). Figure shows that a linear function perfectly fits the range of iodide conditions under which the I 2 flux was experimentally derived (Fig. 5b in the main manuscript). This shows that the model, and the derived I 2 flux, is consistent throughout the range of iodide values used in the laboratory experiments and those observed in real polar conditions.
Table S1. QLL Reactions and Rate Constants 28,29 No. Reactions Rate Constants 1. HOI + I - + H + I 2 + H 2 O 4.4 10 12 M -2 s -1 /(volumetric) 2 2. I 2 + H 2 O HOI + I - + H + 0 s -1 3. HOI + Br - + H + IBr + H 2 O 3.3 10 12 M -2 s -1 /(volumetric) 2 4. IBr + H 2 O HOI + Br - + H + 8.0 10 5 s -1 5. HOI + Cl - + H + ICl + H 2 O 2.9 10 10 M -2 s -1 /(volumetric) 2 6. ICl + H 2 O HOI + Cl - + H + 2.4 10 6 s -1 7. HOBr + Br - + H + Br 2 + H 2 O 1.6 10 10 M -2 s -1 /(volumetric) 2 8. Br 2 + H 2 O HOBr + Br - + H + 9.7 10 1 s -1 9. HOBr + Cl - + H + BrCl + H 2 O 5.6 10 9 M -2 s -1 /(volumetric) 2 10. BrCl + H 2 O HOBr + Cl - + H + 1.0 10 5 s -1 11. BrCl + Br - Br 2 Cl - 5.0 10 9 M -1 s -1 /(volumetric) 12. Br 2 Cl - BrCl + Br - 2.8 10 5 s -1 13. Br 2 Cl - Br 2 + Cl - 3.8 10 9 s -1 14. Br 2 + Cl - Br 2 Cl - 5.0 10 9 M -1 s -1 /(volumetric) 15. BrCl + Cl - BrCl 2-16. BrCl 2 - BrCl + Cl - 1.3 10 9 s -1 5.0 10 9 M -1 s -1 /(volumetric) 17. HOBr + I - IBr + OH - 5.0 10 9 M -1 s -1 /(volumetric) 18. HOCl + Cl - + H + Cl 2 + H 2 O 2.2 10 4 e (-3508 / T) M -2 s -1 /(volumetric) 2 19. Cl 2 + H 2 O HOCl + Cl - + H + 2.2 10 1 e (-8012 / T) s -1 20. HOCl + Br - + H + BrCl + H 2 O 3.5 10 11 M -2 s -1 /(volumetric) 2 21. BrCl + H 2 O HOCl + Br - + H + 0 s -1 22. HOCl + I - + H + ICl + H 2 O 3.9 10-14 e (-900 / T) M -2 s -1 /(volumetric) 2 23. ICl + H 2 O HOCl + I - + H + 0 s -1 24. O 2 + 4H + + 6I - 2H 2 O + 2I 3-2.16 10-2 M -2 s -1 /(volumetric) 2 25. I- + I 2 I 3-5.6 10 9 M -1 s -1 /(volumetric) K = 700
Table S2. Henry Constants of iodine species 28,29 Species Henry Constants IO 4.5 10 2 e (5862(1/T 1/To)) M atm -1 HOI 4.5 10 2 e (5862(1/T 1/To)) M atm -1 I 2 3.0 10 0 e (4431(1/T 1/To)) M atm -1 ICl 1.1 10 2 e (5600(1/T 1/To)) M atm -1 IBr 2.4 10 1 e (5600(1/T 1/To)) M atm -1
Table S3. Kinetic experiments for the rate constant determination for the reaction 1: O 2 (aq) + 4H + + 6I - 2H 2 O + 2I 3 - [H + ] 0 [ I - ] 0 [O 2 ] 0 10 3 r(d[i - 3 ]/dt) 10 6 k k 10 2 (mol -2 L 2 min -1 ) (mol -2 L 2 s -1 ) 1 0.001 0.5 1.3 0.94 1.26 2.11 2 0.001 0.5 1.3 0.86 1.15 1.92 3 0.001 1 1.3 1.95 1.32 2.19 4 0.001 1 1.3 2.19 1.48 2.46 5 0.001 2 1.3 4.23 1.43 2.38 6 0.001 2 1.3 3.95 1.33 2.22 7 0.001 1 0.27 0.21 1.46 2.43 8 0.001 1 0.27 0.23 1.64 2.74 9 0.01 0.5 1.3 1.95 0.83 1.39 10 0.1 0.5 1.3 7.59 1.02 1.71 *Initial concentrations ([H + ] 0, [I - ] 0, [O 2 ] 0 ) in [mol L -1 ]; r in [mol L -1 min -1 ] Average rate constant: k = 1.29 (±0.24) [mol -2 L 2 min -1 ] or k = 2.16(±0.40) 10-2 [mol -2 L 2 s -1 ]