WIR SCHAFFEN WISSEN HEUTE FR MORGEN Christophe Delval

WIR SCHAFFEN WISSEN – HEUTE FÜR MORGEN • Christophe Delval, Riccardo Iannarelli and Michel J. Rossi Lifetime Extension of Cirrus Cloud Ice Particles upon Contamination with HCl and HNO 3 EGU General Assembly Vienna 2016, Atmospheric Ice Particles in Session AS 3. 3 (Atmospheric Ice Particles), Wednesday, April 20 2016

Kinetic Data on Pure H 2 O Ice w/o Chamber studies Pure Ice at or close to equilibrium: DYNAMIC SYSTEM ZERO-Order Rate of ev. : Rev = kc [H 2 O]eq a = kc w = (ĉ/4)(S/V) kc - Large spread of a with type of ICE - Negative T-dep. of a for T>190 K - Spread of a as a function of the type of ICE is larger than the T-dependence for T>220 K Page 2

Rate of H 2 O Evaporation from am HCl/H 2 O Ice [H 2 O]eq = Rev / kc a= 1. 0, Rev : for a = 0. 1 Rev/10 at EQUILIBRIUM H 2 O HCl A • Jev = V • Rev Jev = (V/S) • Rev Evaporative Lifetime of small Ice Particles under UT/LS conditions -Jevrh = Jevmax (1 -rh/100) Jevrh = 0 molecule cm-2 s-1 @ rh = 100% -Layer-by-layer kinetic model of evaporation (spherical shell model): time increment dt-n for evaporation/condensation of nth shell independent of r. - dt-n = (4(r-na)2 p NML))/ (4(r-na)2 p. Jevmax (1 -rh/100)) with a the interlayer distance and NML the number of molecules cm-2 (1015 molecule cm-2 for pure ice) - Number of shells: r/a TOTAL evaporation time : θ = (r/a)NML/Jevrh Page 3

Examples: Lifetimes of pure H 2 O Ice Particles • In the kinetic limit the number of shells (molecular layers) evaporating or condensing per s is constant and independent of r • Kinetic limit @ a = 1. 0 is in the range 0. 3 and 1 mm, with a = 0. 1 it is 3 -10 mm • Input Data: r = 10 mm (spherical particle), a = 0. 25 nm (4 bilayers of ice per nm or 4 • 104 layers for 10 mm radius), rh = 80%, Jevmax = 5 • 1016 molecule cm-2 s-1 (pure ice, 200 K), (S/V) = 1/1028, NLM = 1015 molecule cm-2. • Total time to evaporation of particle: θ = (1015 • 4 • 104)/(5 • 1014 • 1028 • 0. 2) leads to θ = 4000 s or 67 minutes at 80% rh. • For 95% rh one obtains θ = 4 • 4000 = 16’ 000 s or 267 minutes or 4. 4 hours, @ ice saturation θ is infinity, at 0%rh θ = 800 s or 13. 3 minutes. For a = 1. 0 θ = 80 s @ 0% rh (Too short for any heterogeneous chemistry to take place). • Conclusion: Large span of total evaporation time θ of a pure ice particle ranging from one minute to 5 hours depending on a and rh! Page 4

Multidiagnostic Experimental Apparatus: Stirred Flow Reactor equipped with MS, FTIR in transmission, QCMB, He. Ne Interferometry, … 12: QCMB insulated with DELRIN (POM) except the Si. O 2 crystal (0. 5 cm 2 area) exposed to the gas phase Page 5

H 2 O Evaporation Rate of HCl-, HBr-H 2 O Ice Jevmax of H 2 O at 210 K as a function of adsorbed HCl on ice (1 mm initial, 70 -200 nm remaining ice thickness). 1 ML of HCl = 3. 0 • 1014 molecule cm-2 , mole fraction χ(HCl) = 5 • 10 -4 for a typical amount of adsorbed HCl of 1. 0 • 1014 (1/3 of HCl ML). 1/3 of a HCl Monolayer Jevmax of H 2 O at 210 K as a function of the relative amount of adsorbed HBr on ice (1 mm initial, 70 -200 nm remaining thickness). A dose of 1 corresponds to an upper limit of 5. 0 • 1013 of adsorbed HBr molecules. Upper limit owing to irreversible HBr adsorption on Teflon. Page 6

H 2 O Evaporation Rate of HCl-, HBr-H 2 O Ice (2) - Orange Triangles: Jevmax smaller by x(3 -6) re pure H 2 O ice for < 1015 HCl adsorbed (3 ML). - Green (inverted) Triangles: Large HCl dose leading to liquid HCl/H 2 O - Black asterisks (*): Jevmax smaller by x 15 re pure H 2 O ice for < 1015 HBr adsorbed (estimate). - No change in H 2 O vapor pressure Peq. H 2 O over ice N. B. good agreement between pink squares (Knudsen reactor) and red diamonds (SFR). Delval et al. , Atmos. Chem. Phys. , 3, 1131– 1145, 2003 Page 7

Yellow Spectrum is an as yet UNKNOWN HCl Hydrate - Yellow Spectru HCl • 6 H 2 O (HCl HH) HCl • 3 H 2 O (HCl Tri H HCl • H 2 O (HCl Mono (H 3 O+Cl-) • n. H 2 O c. f. Desbat & Huong, Spectrochim Acta 31 1109 -1114. Page 8

QCMB–SFR Time Series HCl/H 2 O Evaporation Example: Ice film at 192 K, 1. 33 mm thickness; HCl doping: RHCl = 5. 4 1012 molecule s-1 for 108 s 5. 4 1014 adsorbed HCl (3. 6 ML) D H 2 O (m/e 18) Jeve(H 2 O) Results: d. D = 772 nm Jevb = 4. 0 1016 molecule cm-2 s-1 Jeve = 7. 9 1014 rb/e = 50. 6 HCl (m/e 36) b eginning e nd C. Delval, M. J. Rossi, to be published Page 9

QCMB–SFR Overview Results: avg. value of χHCl Subset B: 3, 4, 7, 8 rb/e: 20 -27 Crystallization? (H 3 O+Cl-) • n. H 2 O All Data combined: 2 -50 Jev. HCl curves start at t. D and end at t. HB before desorption of HCl or TIME Amount of Adsorbed HCl varies from 0. 67 to 36 ML REMINDER: Vapor pressure is that of pure H 2 O ice up to t. Hb Page 10

QCMB–SFR Overview Results: avg. value of χHNO 3 189 -195 K C. Delval, M. J. Rossi, J. Phys. Chem. A 109, 7151, 2005 179 -185 K: rb/e = 3 -15 205 -208 K: rb/e = 60 - rb/e ranges from 2. 7 to 60. 0 in the range 179 -208 K and 0. 13 -7. 33 ML of HNO 3 - rb/e is independent of the HNO 3 deposition protocol (Ri. HNO 3, NHNO 3, …) - Deposited species @ SFR conditions is always NAT (HNO 3 • 3 H 2 O) across whole range of T and χHNO 3 - Up to χHNO 3 = 0. 17 ± 0. 09 Peq. H 2 O is that for pure H 2 O ice Page 11

Evaporation Rates on Binary System NAT, NAD a-NAT MS/FTIR-SFR experiments Full symbols: Pulsed valve + SS expts. (PV) «MT» symbols: 2 -aperture expts. (TO) b-NAT RESULTS: On a- and b-NAT, NAD: Rev. H 2 O < Rev. H 2 O(pure ice) R. Iannarelli and M. J. Rossi, Atmos. Chem. Phys. Discuss. (2016), ms. no. No. : acp-2016 -247 Page 12

Evaporation Rates on Ternary System a-, b-NAT a-NAT MS/FTIR-SFR experiments - Rev. H 2 O > Rev. HCl > Rev. HNO 3 - Rev. HNO 3 independent of HCl b-NAT - Rev. HCl on NAT is approx. x 10 smaller than on HCl HH or amorphous HCl/H 2 O R. Iannarelli and M. J. Rossi, Atmos. Chem. Phys. Discuss. (2016), acp-2016 -247. Page 13

Two Conclusions re Rate of Evaporation (A) Lifetime of 20 mm «ice» particle; (B) Likelihood of «second ice condensate» A Molecular System Ev Flux Jev(M) Lifetime θ/h Dopant Conc. /ML H 2 O 2. 1 1016 2. 6 pure HCl/H 2 O 5. 1 1015 1. 4 1015 10. 9 39. 7 < 3 ML 23 ML HBr/H 2 O 2. 1 1015 26. 5 <3 ML a-NAT/H 2 O 1. 8 1015 23. 1 pure b-NAT/H 2 O 6. 0 1014 69. 4 pure Conditions: T= 190 K, rh = 80%, a measured experimentally, a=2. 5 and 3. 35 Å for H 2 O, HCl-, HBr. H 2 O and NAT, resp. , r=10 mm ice particle, ML for HNO 3, HCl, H 2 O is 6 1014, 3 1014, 1 1015, resp. B Ice once contaminated…. . Gao et al. J. Phys. Chem. A , 2015 (doi: 10. 1021/acs. jpca. 5 b 06357) θ(HNO 3) = 33. 9 d at 85% HNO 3 saturation, θ(HNO 3) = 5. 1 d at 0% HNO 3. Conditions: Polar UT conditions at 11 km altitude (226. 3 mb at 210 K), T = 190 K, 1 ppb HNO 3, (10 ppm H 2 O) corresponding to 85% HNO 3 saturation. Page 14

Wir schaffen Wissen – heute für morgen Relative Humidity and accommodation/evaporation dynamics control ice cloud lifetimes in UT/LS. Once contaminated ice remains «stained» with atmospheric contaminants during its existence in the atmosphere. Page 15