ToF-AMS characterisation of SOA from NO3 oxidation of β - Pinene

Transcription

1 Mitglied der Helmholtz-Gemeinschaft ToF-AMS characterisation of SOA from NO3 oxidation of β - Pinene AMS Users Meeting 28 Astrid Kiendler-Scharr

2 Secondary Organic Particles Current estimates of global biogenic SOA sources: TgC/yr Comparisons field observation model show large discrepancies C1 measurements in OA show large contribution of modern C NO3 as anthropogenic oxidant SOA and organic nitrate yields from NO3 monoterpene Measurements during the international NO3/N2O5 Intercomparison at SAPHIR summer 27 AMS Users Meeting,

3 cylindrical shape 28 m 3 diameter 5 m, length 18 m double wall FEP film, light transmission 85% SAPHIR geöffnet high purity liquid N 2 and O 2 gas replacement flux: m 3 /h AMS Users Meeting,

4 Two experiments β-pineneno3 under dry/wet conditions Measured Parameters: - RH, T, O3, NOx - VOCs, NO3, N2O5 - organic nitrates (NO2-TD-LIF) - SOA number density (CPC) and size distribution (SMPS) - SOA composition (AMS) Submitted to ACP: Organic nitrate and secondary organic aerosol yield from NO3 oxidation of β-pinene evaluated using a gas-phase kinetics/aerosol partitioning model Juliane L. Fry, Astrid Kiendler-Scharr, et al. 28 AMS Users Meeting,

5 Comparison SMPS and AMS: β-pinene NO3, dry T ( C) d (nm) concentration (µg/m 3 ) : Vaporizer Temperature SMPS mode diameter SAPHIR β-pinene NO 3 SOA SMPS mass AMS total CE = 1 Org RIE = 1. NO3 RIE = : 18: : Date and Time AMS Users Meeting,

6 Comparison SMPS and AMS: β-pinene NO3, dry mode diameter (nm) density dry density humid AMS diameter dry AMS diameter humid SMPS diameter dry SMPS diameter humid effective density (g/cm 3 ) : 1: 2: 3: : 5: 6: 7: 8: time since experiment start (h) AMS Users Meeting,

7 Nitrate Diagnostics Resid.. -. Resid Open, Hz 12 8 Open, Hz Closed, Hz 12 8 Closed, Hz Diff, Hz 12 8 NO CH 2 O Diff, Hz NO 2 CH NC 2 H 6. CH 2 O 2 CH NO C 2 H 6 O AMS Users Meeting,

8 Nitrate Diagnostics NO 2 (arb units) NO 2 =.5.1*NO NO (arb units) 2 AMS Users Meeting,

9 Nitrate Diagnostics SAPHIR β-pinene NO 3 SOA Nitrate Diagnostics 1: : 2: Time NO 3 (µg/m 3 ) 2 m/z 6 / : : 18: 21:. NO 3 at m/z NO 3 at m/z 3 NO3_6 = a b*no3_3 a =.13 ±.2 b =.1 ±.7 V_Pr=.93 m31 Frag_org[3] =.893*frag_organic[58],..893*frag_organic[83] 1 2 m3 3 AMS Users Meeting,

10 Organics Composition AMS T ( C) concentration (µg/m 3 ) : : 15: 18: 21: Date and Time Vaporizer Temperature Organics/NO3 SAPHIR β-pinene NO 3 SOA SMPS mass AMS total Org NO3 AMS Users Meeting,

11 Organics Composition AMS T ( C) µg/m SAPHIR β-pinene NO 3 SOA Vaporizer Temperature Total family ratios 2 CHO/NO CH/NO CHO/CH 12: Date and Time 15: 18: AMS Users Meeting,

12 Organics Composition AMS Estimated molar mass of organic nitrates Organic/Nitrate ratio R at T = 15 C assuming all signal at this temperature from organic nitrates R = 2.7 /-.2 results in MW = 229 /- 12 g/mole Fraction of SOA consisting of organic nitrates Two approaches: Organic/Nitrate ratio R = 9 /- 1 throughout the experiment With MW of organic nitrate = g/mole this corresponds to 32-1% of total aerosol mass is organic nitrate At T = 15 C the ratio of AMS mass (.5 µg/m 3 ) to SMPS mass (11.6 µg/m 3 ) corresponds to 39% of total aerosol mass is organic nitrate. AMS Users Meeting,

13 Organics Composition AMS Nitrate equivalent mass (µg m -3 ) MSSD NO MSSD Org m/z AMS Users Meeting,

14 Organics Composition AMS x1-3 Resid Diff, Hz Closed, Hz Open, Hz CH 2 NO 3 CSO 2 N 2 O 3 C 6 H C 2 H 6 NO 2 C 2 H O 3 C 3 H 8 O 2 Resid Open, Hz Closed, Hz Diff, Hz C 7 H 7 NO 3 C 8 H 11 NO 2 C 8 H 9 O 3 C 9 H 13 O 2 C 9 H 15 NO C 1 H 17 O AMS Users Meeting,

15 Organics Composition AMS T ( C) total (µg/m 3 ) concentration mz : : 15: 18: Date and Time Vaporizer Temperature SAPHIR β-pinene NO 3 SOA AMS total mz76 mz153 NO AMS Users Meeting,

16 Organics Composition AMS ratio NO 2 / NO NO 2 / NO NO 2 / NO from NH NO 3 ratio organics/no Organic / NO Vaporizer Temperature ( C) AMS Users Meeting,

17 Comparison dry/humid experiment NO 2 /NO Organics/NO SOA from β-pinene NO 3 dry Experiment RH ~ 6% Vaporizer Temperature ( C) 5 6 AMS Users Meeting,

18 Summary SOA yield ~5% under both dry and humid conditions SOA density 1.6 g/cm3 Organic to Nitrate ratio is ~ 9 Organic nitrates decompose in NO, NO 2 mostly NO 2 /NO ratio ~.1 for SOA studied < than from inorganic nitrate Higher masses containing C, H, N, and O difficult to identify but Peaks found at e.g. m/z 76, 153 AMS Users Meeting,

19 Thank you! AMS Users Meeting,