Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | - 3 ffi , re- NO 3 4 − 25 ppbv cients of 10 ∼ , NH ffi × 4 Chemistry 28 . and Physics Discussions 0 Atmospheric HSO ± 4 29 . Cl were observed at , NH 4 4 and 2 SO , compared with 2 3 3 Cl at 298 K were measured ) − − 4 4 and NH 10 3 × NO 99 . Namely, the uptake coe 4 . and NH 3 1 3 ± NO 4 NO 79 . 4 1–14 nmol N m , respectively. The observed uptake coe < 4 , 8 166 165 2 − , NH 4 and NH HSO 10 4 4 × HSO SO 36 4 . 2 ) 0 4 ± and NH , NH 4 4 78 . SO SO , 1 2 Cl, (NH 2 3 ) ) 4 − 4 4 group. 10 + 4 × 03 . 1 ± Cl was investigated using a Knudsen cell reactor coupled to a quadrupole 4 30 . This discussion paper is/has beenand under Physics review (ACP). for Please the refer journal to Atmospheric the Chemistry corresponding final paper in ACP if available. 2004), their influence onpossible contribution atmospheric to new nitrogen particle cycle formation (Smith (Cornell et et al., 2010; al., Wang et 2003) al., and 2010a). their et al., 2009; Smithof et organic al., nitrogen 2010; species,fog Wang water and et (Ge al., are et 2010b). frequentlysources al., detected including Amines 2011a). livestock, in are biomass They aerosols, anmobiles, burning, are important rainwater, industrial sewage emitted processes, class and treatment, and into meat marine themospheric organisms cooking, atmosphere concentration (Ge auto- of et from alkylamines al., is a 2011b).of variety The ammonia of typical (Cornell at- et al.,have 2003). received significant Recently, attention sources due and to sinks their of potential atmospheric toxicity to amines humans (Gong et al., 1 Introduction Recent field measurements suggestciable that fraction organic of organic nitrogen aerosol species mass may (Beddows be et al., an 2004; appre- Chen et al., 2010; Pratt 298 K. Irreversible exchange reaction andtaking simple place acid-base on reaction (NH forcients MA of was MA found on (NH to be 6 spectively. A linear free energy relationshipbetween was MA found and for NH the heterogeneousMA reactions on these ammonium saltsH were atom in linearly the related NH to the electrostatic potential of the The heterogeneous uptake of methylamine (MA)and onto (NH NH mass spectrometer, inversible situ exchange reactions Raman between spectrometer MA and and NH theoretical calculations. Re- Abstract Comparative study on the heterogeneous reaction between methylamine and ammonium salts Y. Liu, C. Han, C. Liu, J. Ma,Research Q. Center for Ma, Eco-Environmental and Sciences, H.100085, Chinese China He Academy of Sciences, Beijing, Received: 29 November 2011 – Accepted: 22Correspondence December to: 2011 H. – He Published: ([email protected]) 3 JanuaryPublished 2012 by Copernicus Publications on behalf of the European Geosciences Union. Atmos. Chem. Phys. Discuss., 12,www.atmos-chem-phys-discuss.net/12/165/2012/ 165–191, 2012 doi:10.5194/acpd-12-165-2012 © Author(s) 2012. CC Attribution 3.0 License. 5 20 25 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , 3 4 4 SO NO 2 4 HSO 4 , NH 4 SO erential pump- turbomolecular 2 ff ) cient of TMA on 1 4 − ffi turbomolecular pump has been measured as 1 − 4 HSO 4 (Bzdek et al., 2010a, b) between 3 cients of these amines into H ffi to form salt particles. For example, NO and NH 4 3 4 (Lloyd et al., 2009), while the uptake co- 3 − SO . Some amines, such as TMA and triethy- 2 168 167 2 ects the reactivity for this reaction. ) cients of TMA and DMA on clusters (1–2 nm) 10 ff − 4 and NH ¨ ffi a in 2006 and Tecamac in 2007, respectively. , approximately 1 (Liggio et al., 2011; Shi et al., × 4 4 10 ¨ al 2 and HNO × oxidation (Murphy et al., 2007; Gai et al., 2010). In ± 4 SO 4 3 . 2 HSO (Qiu et al., 2011). The uptake coe Cl. The surface species during uptake were investi- SO 4 . The uptake coe 4 –4 4 2 4 2 − are close to unity (Bzdek et al., 2010a,b). The kinetics of SO 3 (Murphy et al., 2007). Therefore, the formation of aminium 10 HSO 2 4 3 × and NH NO 0 . 4 . The uptake coe NO 3 3 particles (Lloyd et al., 2009), and between MA, DMA, and TMA 4 − 3 NO 10 and NH 4 × 4 NO 4 and NH 4 . er) and an ion gauge (BOC Edward). The vacuum chamber between the 4 SO , NH ff 2 cient of ammonia by H 4 –3 ) has been measured as 2 3 Cl based on theoretical calculations. The environmental implications for these 4 ffi − 3 4 HSO SO 4 2 10 (Silva et al., 2008), OH or O ) NO 4 × 3 4 cient for MA, DMA, and TMA by (NH In this study, we investigated the heterogeneous uptake of MA on NH In field measurements, alkylamines are usually internally mixed with sulfate and ni- Smith et al. (2010) found that aminium salts accounted for 23 and 47 % of the new 6 . ffi QMS and the Knudsenfor the cell mass reactor spectrometer was and pumped ion gauge by (both a from 60 BOC l s Edward) di 2 Experimental details 2.1 Uptake experiments We used a Knudsenconduct cell the kinetic reactor experiments coupled (Liutrometer to et was a al., housed 2009a,b, QMS in 2010b,c).pump (KCMS, a Briefly, (Pfei Hiden, vacuum the chamber HAL mass equipped spec- 3F with PIC) a to 300 l s a Knudsen cell reactorfree coupled energy relationship to was a observedand quadrupole for NH the mass uptake spectrometer of (QMS). MAreactions onto were A (NH also linear discussed. 2 of NH these reactions in relation toparticle the size amine of structure (Wang thebeen et discussed ammonium in al., few salt 2010a) studies. and (Bzdekproperty At also present of et to date, inorganic al., however, the ammonium it salts is 2010a,b; a not Lloyd clear yet et that how al.,(NH the 2009) have gated using an in situ Raman spectrometer. The kinetic were measured at 298 K using TMA and NH and (NH NH e DMA, TMA, and clusters of NH this heterogeneous reaction would explainand the inorganic aminium formation salts. of Very internal few studies mixture have of investigated organic the reactions between 1999; Swartz et al., 1999),amine. is Conversely, also the one dissociation orequal two constants to orders of that of aminium of magnitudesalts nitrate greater NH by are than acid-base that greater reactions of thanfavored. in or the These presence results of implyorganic typical that and ambient other inorganic ammonia pathways aminium levels contribute saltsammonium is to found salts not in the are the internal major atmosphere.up components mixture onto of of It atmospheric these should pre-existing particles. be particles, noted If they that amines may are form taken particulate organic amines. Thus, trate ions in aerosolsshould (Facchini be et noted, al., however, 2008; thatof ambient Pratt magnitude ammonia et greater concentrations al., thantake tend 2009; coe amine to Smith be concentrations et an (Murphy al., order et 2010). al., It 2007), and the up- the obvious uptake of(TMA) methylamine into (MA), 59–82 wt dimethylamine %are (DMA), H in and the trimethylamine rangelamine of (TEA), also 2 significantlyNO contribute to secondary organicaddition, aerosol Wang et formation al. by carbonyl (2010b) proposed compounds that probably a leadswith Mannich high to reaction molecular between the weight amines in formation and secondary of organic nitrogen aerosols. containing species particle formation observedWith in a Hyyti classactions of strong with bases, acidsMurphy the such et gaseous as al. alkylamines H (2007)into may observed a undergo rapid chamber acid-base particle containing re- gaseous nucleation nitric when acid. amines were Wang injected et al. (2010a) also measured 5 5 20 25 15 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 2 (1) Torr. 5 − air was 1 10 − × 2 . 0 (Guangdong Xi- ± 3 0 0.10 K using a su- . ± is the geometric area NO ) were calculated with (Beijing Chemical Re- 4 g 4 A obs γ ); during uptake experiments SO 2 2 2 ) 4 -BET) were measured around 2 cients ( ffi of simulated air (80 % high purity N 1 − are the mass spectral intensities with the I 170 169 and Cl (Beijing Chemical Factory) were used after be- 0 4 I Torr. After the sample cover was closed, MA gas equi- . Ammonium salt powder was placed into a stainless 1 7 − − . A continuous diode pumped solid state (DPSS) laser 1 − 10 ); and 2 × 0 ) for 2 h at 298 K. Then, ca. 0.5 % of MA in 100 ml min . 2 ective area of the escape aperture (cm ff (Beijing Zhongliante Chemical Co., Ltd.), NH 4 I − I 0 is the e HSO using a Quantachrome Autosorb-1-C instrument. I 4 · h 1 h g − A g A A 2 = Methylamine vapor was generated by 40 wt % of methylamine aqueous solution (Alfa Powder samples of ammonium salts were finely grounded and dispersed evenly on obs within the premise of the densityhybrid functional theory functional (DFT) (B3) using (Becke, Becke’s three-parameter 1993) combined with the electron-correlation functional man spectra were recorded. To avoid thereaction, influence the of sample visible light was on onlyexposure the exposed time heterogeneous to for the each exciting spectrum298 laser K was for during 10 spectra s the collection. with reaction. 6 The scans. The temperature2.3 was held at Computational methods We employ the Gaussianelectrostatic 09 potential suite of of the programs ammonium (Frisch salts. et Geometry al., optimization 2009) were to performed investigate the tions. The diameter of thespectra laser resolution spot on was the 2.0 sample cm steel surface sample was holder focused and at purged 25 µm. withand The 100 20 ml % min high purity O carried by nitrogen from 40 % MA aqueous solution into the reactor and then in situ Ra- In situ Raman spectraa for UV the resonance reaction Raman of spectrometerwhere (UVR ammonium DLPC-DL-03), (Liu salts which et with was al., MA describedsignal else- were 2010a). of recorded Teflon The on at instrumentbeam 1378 cm was (532 nm) calibrated was against usedranging the from as Stokes 0 the to Raman exciting 200 mW.ification radiation, A was source with observed power the when with 50 the adjustable mW sample source was was used power irradiated and under no sample the mod- experimental condi- long Chemical Company) anding NH finely grounded.0.1 m Their specific surface areas (N 2.2 In situ Raman spectra measurements gent), NH γ Aesar). Analytical grade ammonium salts including (NH a Knudsen cell equation2000). (Tabor et al., 1994; Ullerstam et al., 2003; Underwood et al., Where, of the sample holdersample holder (cm closed and open, respectively. through the leak valve.valve The and pressure measured using in the thePrior absolute reactor, to pressure which transducer, the was was experiments, 3 controlleduntil the by a reactor steady the chamber state leak QMS wasgas signal passivated by was with the established amines as sample the cover. for samples The 90 were min observed isolated uptake from coe the connected to a linear translator.with The an temperature embedded of Pt theper resistance sample thermostat holder thermometer and was and cryofluid measured pump heldLtd.). (DFY-5/80, at Henan Yuhua 298 laboratory K instrument Co, the Teflon sample holdersure and of then approximately 5 out-gassed atlibrated 298 K with for 40 wt 8 % h methylamine to reach solution a was base introduced pres- into the reactor chamber controlled by a leakadjustable valve, an iris, escape and aperture abath. whose The area sample area could holder of be the attachedand modified escape measured to aperture with according was an the to set methods top at reportedThe 0.88 previously sample ceiling mm (Liu in of et the al., sample a 2009a,b, holder 2010a,b). circulating was exposed fluid to or isolated from the reactants by a lid ing. The Knudsen cell reactor consisted of a stainless steel chamber with a gas inlet 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , = 4 17 18 30, may = = SO = 2 2 m/e ) 36 was 4 = NH m/e m/e and show m/e 3 3 Cl were ex- 4 17, m/e ) basis set was = p ) also contributed 3 , and CH , 2 3 and NH m/e df 3 31) only contained two Cl. = 4 NO Cl samples were exposed 30 and 31) was classified O, NH 4 4 G (2 2 = . As shown in Fig. 1g, a con- 4 m/e ++ 18 was about 0.3 in pure water 17 mass channel was ignored ) had the strongest intensity, fol- = = SO m/e 2 2 ) 17, the mass channels of 4 , and NH erent from that of MA, though it also NH 3 = ff m/e 2 30 and m/e ). Therefore, these two mass channels = 2 17 when NH NO 4 = m/e NH 3 m/e 30 (CH 172 171 , NH sample was exposed to MA vapor. The first O to = m/e O to the 4 Cl samples, the mass channel of ) may have also contributed to this mass chan- 2 2 4 4 3 sample was exposed to MA vapor. Because the 17 to that of 31 (CH SO (Fig. 1e–g). It should be pointed out that the signal 4 m/e = HSO (NH 2 = 4 ) 4 2 4 Cl at 298 K. According to the fragmentation patterns 4 HSO m/e NH 4 m/e HSO 3 4 17 was monitored for the possible product of NH sample was exposed to MA, the original profile for the ). The same phenomenon was observed during the whole up- 18) when other samples were exposed to MA vapor (Fig. 1h, 4 = 2 = , and NH 3 SO NH 2 17 in Fig. 1c exceeded its baseline in the second stage (about 3 min 17 can be mainly ascribed to consumption of MA. Figure 1k, o show 3 ) m/e O to this mass channel was not important, the decrease of the signal 4 2 = = NO m/e 4 O (OH) and CH 31 in the first stage suggested that these three mass channels had the m/e m/e , the fragment peak at 2 , NH 2 = 4 18 remained almost unchanged when the sample was exposed to MA vapor. NH 3 = m/e HSO O) shown in olive color was scanned because gaseous MA was generated using 4 2 When the (NH As shown in Fig. 1a, b, the signal change of MA ( the evolution of the signal intensity of take stage for MA ontointensity NH of after the sample covermaximal was value opened) (about and 10 min). decreasedto slowly This this with implied mass channel time a during gaseous aftertinuous uptaking product reaching decrease MA (NH a onto with (NH anwas amplitude observed around when 28 % thecontribution for NH of the H signal intensityintensity of of l, p). Therefore,because the the contribution intensity ratio of of H vapor (NIST). In Fig. 1c, theand synchronous decrease in intensitysame of source (CH 17 mass channel (Fig. 1c)included was, the however, quite three di stages,sity. that The is, complicated patterns acontributed of decrease, to its increase this signal and mass profilecontribute channel. then implied to decrease that As this more mentioned in mass than above, inten- m/e channel. H one species As shown inSo Fig. it 1d, does however, the (for signal intensity of recovered about 10, 13, andbe 33 ascribed % at to 30 desorption min,the experiments respectively. of were The MA conducted signal in orindicated recovery a consumption the should steady-state, loss of the of decrease active MA insalt sites molecules MA samples. from signal over gas intensity time. phase to Because the surface of these ammonium the second stage, the signal intensities of MA gradually increased with time and finally stages. In the firstthe stage, it lowest decreased values dramatically, with followed by the a maximal gradual amplitudes decrease of to 78, 75, and 38 %, respectively. In into three stages afterstage was the the (NH remarkable decreasethe in first intensity 2 with min. maximal Thethe amplitude second third of was stage 67 % the with within quick a3 recovery min slow of stage recovery the (from rate. second 2 stage, SignalAs and to intensity recovered shown 5 a recovered min) in further about Fig. followed 35 40 by % 1,to % within when within 30 MA the min of NH vapor, the the third stage. signal intensity of MA ( peaks of H nel. To determine the contribution(H of H 40 wt % MA aqueous solution.additionally For scanned NH for monitoring the decomposition of NH 3.1 Uptake of MA onto inorganicFigure ammonium salts 1 showsNH the typical massof CH spectra profileslowed for by the MA parent peak uptakewere at scanned onto for MA (NH measurement andmass shown channel in of blue and redin color, black respectively. color The for the original signal and purple color for corrected one. The fragment used for all the calculations. 3 Results and discussion of Lee, Yang, and Parr (LYP) (Lee et al., 1988). 6-311 5 5 25 15 20 10 20 25 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) 1 3 4 − in 1 2 4 − Cl, − 2 and and 4 was (R1) (R2) (R3) (R4) (R5) NO , ex- 4 4 3 1 4 HSO − 4 NO 4 , NH HSO HSO 4 4 was related 4 (2986 cm 1 3 − SO 2 Cl occurred un- ) 4 , 63.9 mg NH from 0.88 mm 4 3 2 at 1048, 1017, 884, Cl. However, when 4 − 4 NO particles (Lloyd et al., 4 ) and CH 3 and NH 1 3 − (Kruus et al., 1985). It was with the increase of SO NO and NH 4 1 17 show the corrected signal − 4 NO was observed as a shoulder − 3 4 = 1 ions, the exchange reaction be- sample, the band at 2981 cm 3 − (Qiu et al., 2011). NO 4 + 4 4 4 , NH , 59.8 mg NH m/e NH 4 4 3 SO SO + 2 to MA, then leading to the formation of ) 2 4 sample was exposed to MA vapor, new , NH SO ) 4 4 NH 2 4 − 4 3 ) at 976 cm ) HSO 1 + 4 4 SO v ), C–N (1008 cm 4 2 SO ( ) NO 4 1 2 173 174 3 3 4 ) − − 4 2 4 , a simple acid-base reaction occurred and the )SO 4 )SO NH 4 NH 4 3 3 increased with time. The band at 1008 cm + and (NH 1 3 2 (NH − NH HSO (NH (978 cm (CH 3 4 3 + NO , 60.5 mg NH NH − 3 4 → 2 4 3 NH and those on the top right corner show the spectra in the Cl 4 NH 3 may involve two steps. Similar exchange reactions have 3 1 3 NH SO − 4 . When the NH molecule contains two NH 3 2 CH 1 ) 17 occurred intermediately at the same time as NH . These results were also well agreement with Knudsen cell NH )SO 4 CH 4 − 3 − 4 4 = SO CH → 2 → after the contribution of MA to this mass channel was subtracted, ) SO 4 CH 27 (Fig. 1e, g). 4 4 2 → (Kruus et al., 1985) decreased in intensity with time, accompanied 3 . (NH ) 3 3 0 4 1 m/e SO → Cl. The changes of other bands attributing to (NH should be the reactive site. These reactions can be summarized as − 2 = 4 ) (Purnell et al., 1976). For (NH NH HSO NO Cl 4 − 4 3 4 4 4 30 3 I ∆ was exposed to MA vapor, the bands attributing to HSO (NH CH NH NH NH / (Bzdek et al., 2010a,b), between TMA and NH 4 + + + + + Cl were unobservable. These results well supported the exchange reactions 17 4 I 3 2 2 2 2 2 ∆ . This result demonstrated that the active site for uptake of MA onto NH NH NH NH NO HSO NH NH Cl samples uptake MA. The purple curves for − 2 4 3 3 3 4 4 3 3 4 Therefore, based on these results, we concluded that except for NH Figure 2 shows the in situ Raman spectra for the heterogeneous reaction of MA with CH follows. proton in HSO CH CH bates from 58.2 mg (NH respectively, after exposed to MA for ca. 30 min. To investigate the stability ofments were aminium performed salts after the formed completion onwas of the the isolated uptake surface, experiments. from desorption After the the experi- the feed sample reactor gas was by stopped. the Whenlished, a sample the steady-state cover, sample of the cover mass was introduction spectrometry openedwith signal of and the was feed the estab- QMS. desorbed gas The species into escape weresome monitored aperture cases online area using was the increased variablereactor iris to into to 5.5 the mm increase QMS the detector.during gas The uptake flow mass experiments. rate channels from were Figure the scanned Knudsen as 3a–d cell the show same the as mass that spectra of the cared desor- der these conditions. As for NH NH 2009), and between MA, DMA, TMA and (NH 3.2 Stability of aminium salts with obvious increase ofin SO MA. The synchronoussuggested the decrease transfer in of H intensity protonSO of from HSO HSO was the proton inexperiments. HSO change reaction between CH CH CH Because one (NH tween MA and (NH been observed in previous studies between DMA, TMA, and clusters of NH inversed for NH and NH discussed above between MANH and (NH 578, and 415 cm ammonium salts at 298 K. Thethe insert range graphs of in purple 950–1080 cm boxrange show the of enlarged 2500–3600 cm spectra in bands at both 1008ascribed and to 2981 cm the stretch vibrationto of that C–N of in CH MAwas and the observed band obviously at 2981peak while cm because the of the band strong at peak of 1008 cm SO in the intensity of NH originating from NH using posed to MA vapor, respectively. Unlike those shown in Fig. 1c, g, significant increase 5 5 20 15 25 10 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) ) = 2 2 30 ect and and was ff = cient NH 4 ) was h 4 2 of MA ffi m/e 2 used in A (Fig. 3c, h SO SO m/e 3 (5.5 mm obs under low 2 NH 2 A ) ) 2 γ 997), either surface oc- h 3 4 4 . from the MA 30 in Fig. 2d, A 60 calculated 0 4 . 2 = 30 and 0 = are stable under (as well HCl, not = = NH R 3 4 HSO 3 , 31 decreased syn- 4 30. However, when 30 m/e I 30 = cient as a function of and HNO I SO = ∆ m/e 2 ffi 3 / ) 30 in Fig. 3c. 60 3 . . The normalized ratio of 31 Cl, respectively. Only ob- = 0 I m/e 3 and CH 4 m/e 30 is neglectable. Thus, in and NH ∆ NH = 2 was observed at 298 K from 3 = Torr and at 298 K (not shown) 4 NO 31 3 m/e 4 I 6 NH − 2 cient of MA on (NH SO 30 and 2 m/e and NH ffi 10 ) 31 ( 30 was used for uptake coe 4 = 3 × = = and (CH 2 . 4 NO decreased with exposure time (Fig. 3a) 4 m/e m/e 4 m/e Cl contributes 12 % to the intensity change 30 mass channel, while the signal change )SO 3 4 = SO 176 175 2 . According to the NH ) samples even though a maximal 2 3 4 (NH 4 Cl, while the reason was not clear yet. According 3 occurred under these conditions. In Fig. 3e, the m/e 4 NH easily decomposes into NH 3 Cl also showed a slow decline with time after the 3 ), desorption of CH according to Eq. (1). As discussed above, decom- NH 4 2 3 3 HSO NO 4 obs 4 NO 30 signal change in Fig. 3c. Therefore, the increase in γ Cl sample was very weak, while release of NH 4 4 31 when the sample cover was opened. In Fig. 3c, both = are negligible under these conditions. Figure 2e, f show when evacuated at 1 27 and the change of signal intensity of = . 4 was 0.85. This also meant that desorption of MA (CH 4 0 ) of MA on (NH , and NH and NH 2 was observable in Fig. 2d, desorption of NH was partially reversible under these conditions. Although des- 3 = Cl was unobservable in Fig. 3f. It meant that surface bounded m/e 4 3 4 3 m/e NH and NH HSO obs 30 can contribute to the mass channel of 2 HSO I 4 NO γ 4 3 3 SO 4 could be normalized to 1 because the mass channels of ∆ NO CH Cl was also partially reversible under these conditions. 2 . These results also indicate that the exchange reaction between 4 / ) + 4 3 4 NO NO 17 4 I 4 , NH 30 in Fig. 3d. Thus, we can conclude that the exchange reaction between NO 4 30(NO) 30(NO decomposition to the signal intensity of and NH 4 and NH 17 were the result of the dissociation of NH I I = is irreversible and CH 3 4 4 ∆ ∆ 31 only resulted from CH = and NH and NO contributed to the and NH 4 / / ) ) HSO 2 2 2 = 30 signal intensities (Fig. 3c) were mainly from the decomposition of the un- 3 3 30 was linearly correlated with that of NO SO SO 4 m/e 4 2 2 ) ) = = m/e NH NH HSO NH 4 4 3 3 4 2 m/e 17(NH 17(NH Figure 4 illustrate typical profiles of the observed uptake coe It should be noted that NH As shown in Fig. 3c, d, when the sample cover was opened with the same As shown in Fig. 3a, b, no desorption of MA and NH I I dissociation of aminiumcurred; salts formed therefore, on the the decrease (NH in the uptake coe the signal change inof Fig. NH 2e was comparedthe to following that section, in the Fig.calculations. signal 1i, intensity the of compensation e time at 298 K. The corresponding to the recoveryon of NH the MAmaximal signal value (Fig. was 1a). reached. As In discussed Fig. above, 4, neither the desorption of MA nor the As discussed above, the signalchronously intensities when of them/e sample cover wascan be opened. used toposition calculate Because of the NH the signal intensity of MA might change the stabilityto of the NH value of we estimated that decomposition of CH of the CH 3.3 Kinetics of MA uptake onto ammonium salts m/e reacted NH CH orption of MA and NH shown) from pure NH explained 15 % of the and ∆ dergo decomposition reaction. Therefore, themonium decomposition salts experiments were for pure performed am- under(NH the similar conditions. Thewere mass the spectra same for pure as(NH those shown in Fig.the 2a, mass spectra b, of which desorbatesservable suggested from decomposition that pure decomposition of NH of NH ∆ of in Fig. 1 andestimated contributing the 15 % signal to intensity the signal in change Fig. of the 3c,pressure conditions the (Lightstone fragment et ion al., of 2000). MA (CH Other ammonium salts might also un- the uptake experiments (0.88 mm exchanged NH d) was very clear.used To through increase the adjusting signal17 the of mass iris. the channels mass increased spectrometer,the The obviously maximal mass signal and channel were intensities of accompaniedCH of by the a faint increase in MA treated (NH was used. ThisNH indicated that the uptakethese conditions. of This MA was similar ontoor to the TMA the irreversible and surface exchange ammonium reactions of bisulfate between (NH clusters DMA reported by Bzdek et al. (2010a). 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , , . , , 4 4 4 3 3 obs − df and γ SO cient SO NO 2 10 usion 3 2 4 ) ffi HSO ff ) 4 × 4 4 G (2 NO erence in cient with 4 03 group and ff , NH . ++ ffi 4 cient. How- 1 + 4 ffi ± erent samples erences in the SO ff ff 2 30 ) . 4 Cl at 298 K. 4 cients and MEP were ffi cients were slightly lower Cl, (NH , respectively. The uptake 4 ffi 3 measured in this work are − 3 and NH , with some given reactant B, 10 n 3 NO × for NH ) reported by Lloyd et al. (2009), 4 3 1 NO of MA on all of these ammonium Cl at 298 K was 6 , with a high correlation coe − 28 − 4 4 3 . 0 10 obs ,...,A , uptake coe ± NO 2 γ × , NH 4 . As shown in Table 1, the average 4 4 2 erent reaction systems, di 29 ,A ff . obs ± 1 and NH SO cient is unrelated to sample mass (Qiu et al., γ 2 Cl and NH 3 178 177 ) (2 4 depends on sample mass due to the di ffi HSO 4 4 3 reported by Bzdek et al. (2010a,b). The uptake and 2 NO ) reported by Qiu et al. (2011). The di obs 3 4 , and NH 2 3 γ , NH 4 NO − − 4 , NH 4 is comparable to that on sulfuric acid (Wang et al., NO 4 was the active center. The molecular electrostatic po- 4 10 SO 10 4 , NH 2 SO 2 4 ) × × 2 SO ) 4 Cl were slower than their formation rates. Therefore, ac- 2 4 4 ) . 3 NH 99 4 HSO 3 . 4 HSO –3 1 4 NH and NH 2 3 ± − with the highest MEP had the largest uptake coe 4 Cl, (NH 3 79 10 4 , NH . 4 × NO HSO Cl occurred, while only acid-base reaction took place on NH , 8 6 4 4 4 . 2 cient may be ascribed to di SO and CH − 2 , respectively. Figure 6 indicates the correlation between the uptake ffi ) 3 4 4 10 × NO was ascribed to the depletion of active sites over time. As for NH 3 and NH ) was very close or equal to the 4 HSO t 36 ect of property of ammonium salts on the heterogeneous reaction cult to cover the sample holder with salt particles evenly. Therefore, uptake 4 . 3 erent particle sizes. In the studies by Bzdek et al. (2010a, b), for example, 1– γ ff NH erences in the activation energies are linearly related to the di 9999). NH ffi 0 ff . 3 ff cients of MA onto these ammonium salts with the corresponding MEP. As can cients of MA onto (NH cient of MA onto NH cients of MA onto (NH 0 ± NO Cl, although the exchange reactions were partially reversible, the dissociation rates HSO ffi ffi ffi ffi 4 4 4 = ) level. The geometries for these salts were also optimized at the same level and Figure 5 shows the MEP of ammonium salts calculated at B3LYP/6-311 Previous research has found that 78 p . R observed among NH ( 2 the true minimal wasmaximal confirmed value without for imaginary electrostatic frequency. potentialwere As located 827.58, shown 1386.38, at in 1741.85, the Fig. andand H 637.42 5, kJ atom the NH mol in thecoe NH be seen in Fig. 6, a linear correlation between the uptake coe heats of reaction, namely, atential linear can free be energy used relationship.at as some Because a electrostatic particular measurement po- of sitesenergies thermodynamic, in with B. the such Therefore, electrostatic MEP a potentials isand series also kinetics of used (Politzer et to molecules correlate al., are with 1985). the related reaction to mechanism their interaction Above results demonstratedNH that exchange reactionIn general between speaking, these MA reactions canthe and be lone-pair regarded electron as (NH in electrophilic CH reaction,tential in which (MEP) is widelythe used electrophilic as attack a of reactivity chargedactions map point-like of displaying reagents a most (Politzer series et probablethe of al., regions di related 1981). for molecules, In A the re- with di 2 nm clusters of bisulfatepresent or study. nitrate were used, while crystal samples3.4 were used in the E the uptake coe 2010a). As for the uptakethan of the MA on value (NH (2 ficient ( of MA on (NH 1 coe comparable to that ofwhile TMA they on are NH two orders ofon magnitude clusters lower of than NH the valuescoe for DMA and TMA uptake salts. This indicatesuptake. that This the phenomenon underlayers also supported ofexposure the time the slight (Fig. sample 4) declines because of contributedphenomena the uptake very was coe reactions little also were confined to observed(Qiu on MA for the et the surface. al., uptake 2011). The of same Therefore, MA, it was DMA, reasonable and to TMA speculate on that (NH the true uptake coef- of reactant gas into2009a, the b, underlying 2010b, c; layers Ullerstam ofies et have the al., found, multilayer 2003; however, that powder Underwood uptake et coe sample2011; al., (Liu Seisel 2000, et et 2001). al., al., Somea 2005). stud- wide In range the of presentwas sample work, di masses. we performed Whenexperiments uptake the on experiments sample samples on mass with wasmass masses lower lower dependence than than was 40.0 40 mg, mg not it were observed not for performed. the Sample NH of CH cessible active sites alsocoe decreased with time. Table 1 summaries the initial uptake NH 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , , 4 4 on 3 SO SO − cients cients 2 2 ) ) ffi ffi 4 4 10 usion of ff × 28 . Cl, while it is 0 4 Cl, (NH ± 4 29 . or NH cients of MA on 62– 4 ffi measured in this work. doi:10.5194/acp-10-3495- at 283 K. This is four to and 2 4 SO 2 3 2 cients because di − ) − ffi 4 10 10 group, in which H atom should HSO 4 × × + 4 5 , (NH . 99 3 . 0 1 ± ± NO 2 Cl were investigated by using Knudsen 4 . Cl were observed, while acid-base reac- 4 79 4 . . The exchange reactions between MA and Cl at 298 K, respectively. As for (NH to 3 4 , 8 180 179 4 2 2 − cients were highly linear related with the MEP − ffi and NH 10 HSO and NH 10 4 were observed. The observed uptake coe 3 × 3 × 4 and NH 2 cient of MA onto NH 36 NO . . NO for MA on NH 3 4 ffi 0 4 0 HSO ± ± NO 4 obs 0 4 γ , 2010. . , NH , NH 78 group. 4 . 4 + 4 , 1 are considered the main source of particulate aminium salts. , NH 3 SO 4 , the uptake coe 2 − 3 HSO and NH ) 3 4 This research was funded by the National Natural Science Foundation of to be 2 4 4 Cl were found to be reversible, while irreversible reaction between cients of MA on them are considered, uptake of MA onto ammonium 10 4 4 HSO NO obviously deviated this linear relationship. This deviation can be as- ffi × erent reaction mechanism as discussed above. This result also implied 4 4 SO , NH 4 ff 2 SO 4 03 should be adsorption of MA onto the NH ) . 2 or HNO 4 3 1 , NH 4 SO 4 ± HSO 2 and NH 4 ) NO 4 3 4 SO 30 , 2010a. SO . 2 2 ) Cl, and NH NO 4 4 4 ammonium nitrate nuclei, Atmos. Chem. Phys., 10, 3495–3503, Size fractionationnitrogen and molecular indoi:10.1029/2010jd014157 composition aerosols of of water-soluble a inorganic and coastal organic environment, J. Geophy. Res., 115, D22307, Nicholson, D. H., andbackground Thompson, atmospheric aerosol K. in C.: thespectrometry, UK J. Correlations determined Environ. in Monit., in 6, real the 124–133, time chemical 2004. using composition time-of-flight mass of rural 2010 fate clusters with dimethylamine, J. Phys. Chem. A, 114, 11638–11644, 2010b. Phys., 98, 5648–5652, 1993. Field measurements have found that aminium salts are usually internally mixed with Cornell, S. E., Jickells, T. D., Cape, J. N., Rowland, A. P., and Duce, R. A.: Organic nitrogen de- Bzdek, B. R., Ridge, D. P., and Johnston, M. V.: Amine exchange into ammonium bisulfate and Chen, H., Chen, L., Chiang, Z., Hung, C., Lin, F., Chou, W., Gong, G., and Wen, L.: Bzdek, B. R., Ridge, D. P., and Johnston, M. V.: Size-dependent reactions of ammonium bisul- Beddows, D. C. S., Donovan, R. J., Harrison, R. M., Heal, M. R., Kinnersley, R. P., King, M. D., Becke, A. D.: Density-functional thermochemistry. III. The role of exact exchange, J. Chem. at least suggest that aminesunder uptake onto particular pre-existing circumstances, ammonium saltsconcentration as may of contribute, high acidic gas concentrations species, of to the ammonium atmosphericAcknowledgements. salts source of and particulate low amines. China (50921064, 20937004 and 20907069). References large uptake coe salts should not bewere ignored. carried Of out course, under itstudied. should dry be condition In pointed and thesurface out the might that real clean our have atmosphere, experiments complex surface high influence of relative on ammonium humidity this salts reaction. and was organic However, the species measurements on the When the abundance of ammonium salts in the troposphere as well as the relatively ten times higher thancomparable the to the uptake coe NH of the H atom in the NH inorganic ammonium saltsPratt in et atmospheric al., 2009; particulate Smithand et matter H al., (Facchini 2010). et InFor general, al., example, acid-base reactions 2008; Wang between et82 amines wt % al. of (2010a) H measured the uptake coe MA and (NH of MA on these saltsMA can into be the used underlayers of aswere 6 the powder samples true was uptake coe neglectable.(NH The uptake coe 4 Conclusions and atmospheric implications In this work, the heterogeneousing reactions (NH of MA on thecell typical reactor, ammonium Raman salts spectroscopy and includ- theoreticaltween calculations. MA Exchange and reactions (NH be- tion was found between MANH and NH cribed to the di that the first step for theand heterogeneous NH reactions between MA andbe NH the active site. ever, NH 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ective ff doi:10.5194/acp-10- orescence, and water ffl doi:10.5194/acp-7-2313- and MgO, Atmos. Chem. Phys., 9, ect of water on the heterogeneous ff 3 O 2 -Al α , Phys. Chem. Chem. Phys., 12, 10896–10903, 3 182 181 , 2009b. , 2010c. doi:10.5194/acp-9-6273-2009 , 2010b. , 2007. tool for the1985. elucidation of biochemical phenomena, Environ. Healthphase Persp., amines, 61, Environ. Sci. 191–202, Technol., 43, 5276–5281, 2009. Raman matrix isolation studies of methylamine, Chem. Phys., 12, 77–87, 1976. ping, E., Flagan, R.reactions C., of and aliphatic Seinfeld, amines, J. Atmos.2007 H.: Chem. Secondary Phys., 7, aerosol 2313–2337, formation from atmospheric Potentials, Plenum, New York, 1981. nium nitrate particles, J. Phys. Chem. A, 113, 4840–4843, 2009. doi:10.1029/2010JD014778 10335-2010 kaolinite within a temperature range of 220–330 K, J. Geogorphy. Res., 115, D24311, into a functional of the electron density, Phys. Rev. B,sulfuric 37, acid 785–789, aerosols 1988. by competing45, uptake 2790–2796, of 2011. ambient organic gases, Environ. Sci. Technol., reactions of carbonyl sulfide6273–6286, on the surface of 2010a. mechanism and kinetics study, Atmos. Chem. Phys., 10, 10335–10344, aqueous solutions by Raman spectroscopy, J. Solution Chem., 14, 117–128, 1985. erogeneous reaction of carbonyl sulfide3394, on 2009a. magnesium oxide, J. Phys. Chem. A, 113, 3387– soot during heterogeneous reaction with O ties and gas/particle partitioning, Atmos. Environ., 45, 561–577, 2011a. 45, 524–546, 2011b. and their chlorinated forms, Environ. Toxicol. Chem., 23, 239–244, 2004. activity in ammonium nitratePhys. Chem. and A, mixed 104, 9337–9346, ammonium 2000. nitrate/succinic acid microparticles, J. diethylamine and triethylamine, Acta Phys.-Chim. Sin., 26, 1768–1772, 2010. Calmani, V., Barone, B.,Hratchian, Mennucci, H. G. P.,Ehara, A., Izmaylov, M., Petersson, A. H., Toyota, F.,Kitao, K., Nakatsuji, Bloino, O., M., Fukuda, J., Nakai, Caricato, R.,Bearpark, Zheng, Li, J. H., Hasegawa, J., G., X., Vreven, J., Heyd,mand, E., Sonnenberg, T., K., Ishida, Brothers, Raghavachari, J. Montgomery, M., K. A., Rendell, N., L.,Rega, J. Nakajima, J. Kudin, C., J. A., Hada, T., V. Burant, N., M., S. Honda, M., PeraltaJaramillo, Staroverov, S., R., Y., Iyengar, Millam, Jr., R., J., Kobayashi, J., Tomasi, J. M., M., Gomperts, Nor- Pomelli, Cossi, E. Klene, J. N., R. W., F., J. Ochterski, E., Ogliaro,Salvador, E., R. J. M., J., Stratmann, L., Knox, Dannenberg, Martin, S., O., J.Ortiz, Dapprich, K., J., B., A. Yazyev, and Morokuma, D., A. Cioslowski Daniels, Cross, V. Fox, O., G., J., D. V., Farkas, J.: Zakrzewski, J. Gaussian Austin, Bakken, B., G. 09; Foresman, C., A., R., Gaussian, J. Inc., V., Voth, Adamo, Wallingford, Cammi, P., CT, 2009. J., C., Moretti, F., Tagliavini, E.,secondary Ceburnis, organic aerosol D.,2008. from and biogenic O’Dowd, amines, C. Environ. D.: Sci. Important Technol., 42, source 9116–9121, of marine position on land and coastal37, environments: 2173–2191, 2003. a review of methods and data, Atmos. Environ., Purnell, C. J., Barnes, A. J., Suzuki, S., Ball, D. F., and Orville-Thomas, W. J.: Infrared and Politzer, P., Laurence, P. R., and Jayasuriya, K.: Molecular electrostatic potentials: An e Pratt, K. A., Hatch, L. E., and Prather, K. A.: Seasonal volatility dependence of ambient particle Politzer, P.and Truhlar, D. G. (Eds.): Chemical Application of Atomic and Molecular Electrostatic Murphy, S. M., Sorooshian, A., Kroll, J. H., Ng, N. L., Chhabra, P., Tong, C., Surratt, J. D., Knip- Lloyd, J. A., Heaton, K. J., and Johnston, M. V.: Reactive uptake of trimethylamine into ammo- Liu, Y. C., Ma, J. Z., Liu, C., and He, H.: Heterogeneous uptake of carbonyl sulfide onto Liggio, J., Li, S.-M., Vlasenko, A., Stroud, C., and Makar, P.: Depression of ammonia uptake to Liu, Y., Ma, Q., and He, H.: Comparative study of the e Liu, Y., Ma, J., and He, H.: Heterogeneous reactions of carbonyl sulfide on mineral oxides: Lee, C., Yang, W., and Parr, R. G.: Development of the Colle-Salvetti correlation-energy formula Liu, Y. C., Liu, C., Ma, J. Z., Ma, Q. X., and He, H.: Structural and hygroscopic changes of Kruus, P., Hayes, C. A., and Adams, W. A.: Determination of ratios of sulfate to bisulfate ions in Liu, Y. C. and He, H.: Experimental and theoretical study of hydrogen thiocarbonate for het- Gong, W. L., Sears, K. J., Alleman, J. E., and Blatchley, E. R.: Toxicity of model aliphatic amines Ge, X., Wexler, A. S., and Clegg, S. L.: Atmospheric amines – Part I. A review, Atmos. Environ., Lightstone, J. M., Onasch, T. B., and Imre, D. O., S.: Deliquescence, e Ge, X., Wexler, A. S., and Clegg, S. L.: Atmospheric amines – part II. Thermodynamic proper- Gai, Y., Ge, M., and Wang, W.: Rate constants for the gas phase reactions of ozone with Frisch, M. J., Trucks, G. W., Schlegel, H. B., Scuseria, G. E., Robb, M. A., Cheeseman, J. R. G., Facchini, M. C., Decesari, S., Rinaldi, M., Carbone, C., Finessi, E., Mircea, M., Fuzzi, S., 5 5 30 25 20 15 30 10 25 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | on amor- 2 doi:10.5194/acp-5- ¨ om, E.: DRIFTS and Knudsen cell study on mineral dust, Atmos. Chem. Phys., 3, 2 184 183 , 2003. and NO 2 doi:10.5194/acp-3-2043-2003 , 2005. ¨ orensen, C., Vogt, R., and Zellner, R.: Kinetics and mechanism of the uptake of on mineral dust at 298 K, Atmos. Chem. Phys., 5, 3423–3432, 5 O 2 of the heterogeneous reactivity2043–2051, of SO heterogeneous reactivity of nitric acid105, on 6609–6620, oxide 2001. and mineral dust particles, J. Phys. Chem. A, parameters of potentiallywith important a heterogeneous Knudsen cell atmospheric reactor, J. reaction Phys. on Chem. A, solid 104, particle 819–829, 2000. sulfuric acid: Implications forTechnol., 44, atmospheric 2461–2465, formation 2010a. of alkylaminium sulfates, Environ. Sci. and Seinfeld, J. H.:urban Evidence aerosols, for Environ. high Sci. molecular Technol., 44, weight 4441–4446, nitrogen-containing 2010b. organic salts in phous carbon at ambient temperature, J. Phys. Chem. A, 98, 6172–6186, 1994. trate radical reaction in the atmosphere, Environ. Sci. Technol., 42,man, 4689–4696, J. H., 2008. Williams, B. J.,nanoparticles and McMurry, and P.H.: possible Observations of2010. climatic aminium salts implications, in Proc. atmospheric Natl. Acad. Sci.,phase 107, ammonia. 6634–6639, 2. Uptake1999. by sulfuric acid surfaces, J. Phys. Chem. A, 103, 8824–8833, N ammonia. 1. Uptake by aqueous8823, surfaces as 1999. a function of pH, J. Phys. Chem. A,Cocker, 103, D. 8812– R.: Trimethylamine as precursor to secondary organic aerosol formation via ni- lamines with ammonium sulfate4755, and 2011. ammonium bisulfate, Environ. Sci Technol., 45, 4748– 3423-2005 Ullerstam, M., Johnson, M. S., Vogt, R., and Ljungstr Underwood, G. M., Li, P., Usher, C. R., and Grassian, V. H.: Determining accurate kinetic Wang, L., Lal, V., Khalizov, A. F., and Zhang, R.: Heterogeneous chemistry of alkylamines with Wang, X. F., Gao, S., Yang, X., Chen, H., Chen, J. M., Zhuang, G. S., Surratt, J. D., Chan, M. N., Underwood, G. M., Li, P., Al-Abadleh, H. A., and Grassian, V. H.: A Knudsen cell study of the Tabor, K., Gutzwiller, L., and Rossi, M. J.: Heterogeneous chemical kinetics of NO Swartz, E., Shi, Q., Davidovits, P., Jayne, J. T., Worsnop, D. R., and Kolb, C. E.: Uptake of gas- Smith, J. N., Barsanti, K. C., Friedli, H. R., Ehn, M., Kulmala, M., Collins, D. R., Scheck- Silva, P. J., Erupe, M. E., Price, D., Elias, J., G. J. Malloy, Q., Li, Q., Warren, B., and Seisel, S., B Shi, Q., Davidovits, P., Jayne, J. T., Worsnop, D. R., and Kolb, C. E.: Uptake of gas-phase Qiu, C., Wang, L., Lal, V., Khalizov, A. F., and Zhang, R.: Heterogeneous reactions of alky- 5 25 30 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 3 3 3 3 3 3 3 3 3 ini − − − − − − − − − γ 10 10 10 10 10 10 10 10 10 × × × × × × × × ×

17; and

60.5 mg

0.28 = =17; ± Cl 2 2 2 4 3000 29 . m/e NH NH NH 3 2 (E–H) m/e O 2 , , (E-H) 60.5 4 2000 –––– 4

Cl 4 63.9 2.35 66.1 2.46 81.1 2.35 81.9 1.89 =31 CH =18 H =30 CH =17 OH/NH SO SO 101.7 2.72 103.7 2.01 121.7124.2 2.46 2.09 2 2 Open NH 1000 ) ) Sample m/e m/e m/e m/e 4 Average 2 4 (P) (N) 0 (O) (M) 3 3 3 3 2 2 3 3 3 2 3

ini

− − − − − − − − − − −

γ

10 10 10 10 10 10 10 10 10 10 10 2 × × × × × × × × × × × 2 2 Cl at 298 K. The blue curves NH NH 4 3 2.10 2 3 O 2 3 ± NO Cl at 298 K. The blue curves are for

79 4 NO 4 . 4 =17 OH/NH =18 H 58.2 mg of (NH =30 CH =31 CH NH Open NH 100020003000 m/e m/e m/e m/e 0

(L) (I)

(K) (J) 40.3 8.16 40.1 5.56 59.8 7.76 59.8 9.37 80.1 1.01 80.7 1.01

100.5101.0120.4 8.78 121.0 6.79 1.32 8.07

(A–D)

Sample Average 8 3000 2

2 2 1 63.9 mg NH 2 2 2 2 2 2 2 2 2 2 2 ini NH NH − − − − − − − − − − − 185 186 2 3 O 4 γ Time (s) 2 =31; the black and purple curves are for 2000 10 10 10 10 10 10 10 10 10 10 10 × × × × × × × × × × ×

HSO m/e 4 31; the black and purple curves are for , and (M-P) 63.9 mg NH =18 H =17 OH/NH (M–P) =30 CH =31 CH Open 4 3 1000 0.36 NH = m/e ± m/e m/e m/e NO HSO 78 4 0 . 4 (H) (F) (G) (E)

, and

=18.

m/e

3

NH 2 18. 2 m/e 2

NO

40.4 1.60 39.8 1.90 60.5 1.82 61.5 1.91 85.0 1.90 83.8 1.37 4 = NH NH 103.2 1.33 102.5123.7124.0 2.33 1.35 2.24 2 3 O 4 2 Sample Average 1 SO 2

) m/e 4 3 3 3 3 3 3 3 3 3 3 3 =30 CH ini =18 H =31 CH cients of MA onto ammonium salts at 298 K. =17 OH/NH − − − − − − − − − − − γ Open ffi (NH 10 10 10 10 10 10 10 10 10 10 10 m/e m/e 1000200030004000 m/e m/e Original signal × × × × × × × × × × × , (I-L) 59.8 mg NH Corrected signal 4 0 (A) (B) (D) (C) 59.8 mg NH 08 4 . =30; the red curves are for 1 0 0 0 0 ± SO HSO

2

m/e

8000 6000 4000 2000 5000 6000 4000 2000 5000 4 )

12000 10000 10000 20000 15000 10000

30 4 Mass spectra profiles for uptake of MA onto (A-D) 58.2 mg of (NH (I–L)

u.) . a ( y t i s n e t n i l a gn i . S , 4 Uptake coe (NH Mass spectra profiles for uptake of MA onto 30; the red curves are for

Fig. 1. mg NH

are for and the olive curves are for = 39.8 7.70 41.1 5.19 50.8 5.26 50.9 8.01 58.2 6.45 60.4 6.99 80.8 6.58 79.9 4.82 (mg) (mg) (mg) (mg) HSO mass mass mass mass 100.6101.0 5.53 6.43 4 Sample Average 6 1 2 5 6 7 3 4 m/e the olive curves are for Fig. 1. NH Table 1. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

-1

2 1 − , (D) Torr 3

-6

63.9 mg Torr and 10

NO 6 4 × in left side − . . 2 (D) 1 is 0.88 mm 3000 2000 1000 0 8000 6000 4000 2000 0 6000 4000 2000 0 h -1 − 10 , 2 10000 8000 6000 4000 2000 0 3 A 15000 10000 5000 0 × 2 . 1500 2500 3500 3500 =30 NO =31 =17 1000 4 2000 2000 =5.5 mm m/e m/e

h m/e 0min 30min 60min 3000 =17 =30 A Cl. The is 0.88 mm 800 3000 4 2000 h 2981 1500 m/e m/e A 1000 2500

1500

600 , (C) 59.8 mg NH 2500 -MA 4 4 4 Cl

1500 4 59.8 mg NH 0min 30min 60min 240min 2 1000 400 ) Cl. The Cl-MA HSO HSO 1000 500 4 (C) -1 HSO 4 4 4 Cl Open 4 4 , 1000 4 500 1050 200 =0.88 mm h 1008 A 500 (D) NH (B) NH (F) Pure NH 0 HSO 0

1000 1008

0 976 500

96010201080

4

(B) NH (D) NH

3 in the right side of the dash lines. 800 2 2 188 187 Time (s)

and (F) 60.5 mg pure NH 3500 3500 3 2 2000 2000 60.5 mg pure NH Raman shift (cm 0min 30min 60min =31 =30 , (B) 60.5 mg NH 0min 30min 60min 240min

NO 4 1500 1500 600 4 60.5 mg NH (F) =5.5 mm 3000 3000 h m/e m/e A 2981 SO 2981 2 1500 1500 in the right side of the dash lines. (B) ) and

3

4

, 2 2 3

2500 2500 4 4 -MA 400 1000 1000

=17 =30 4 NO 3 -MA 4 3 NO SO SO SO m/e m/e 2 1000 1000 4 2 2 ) ) ) =17 NO 4 4 4 NO 1040 4 4

Open 200 =0.88 mm 500 500 h Open 1008 m/e A 10001040 1000 1008 500 500 0 (A) (NH (C) NH (E) Pure NH 0 0 (C) NH (A) (NH 0 0 0 0 0 Cl, (E) 59.8 mg pure NH

8000 6000 4000 2000 8000 6000 4000 2000 5000 58.2 mg (NH

4

10000 15000 10000 50000 40000 30000 20000 10000 80000 60000 40000 20000

120000 100000

.u.) a ( y t i s n e t n i l a n g i S 59.8 mg pure NH PS) (C y it s n e t n I Desorption of surface species from MA treated salts and pure salts at 1.2 (A) (E) Desorption of surface species from MA treated salts and pure salts at 1 In situ Raman spectra for heterogeneous reactions of MA with ammonium salts at 298 K. tions of MA with ammonium salts at 298 Raman spectra for heterogeneous reac Cl, 4 in left side of the dash lines, and it is 5.5 mm 63.9 mg NH Figure 3. and at 298 K. (A) 58.2 mg (NH of the dash lines, and it is 5.5 mm NH Fig. 3. at 298 K. Fig. 2. The insert graphs in purple boxes show the enlarged spectra in the range of 950–1080 cm and those on the top right corner show the spectra in the range of 2500–3600 cm In situ

19 20 21 22 18 16 17

Fig. 2 show the enlarged spectra in the range of 950-1080 cm K. The insert graphs in purple boxes the spectra in the range of 2500-3600 cm and those on the top right corner show 8 9 12 13 14 15 10 11

Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

0.00 0.003 0.002 0.001 0.000 0.02 0.01 4 3000 3000 Cl 4 HSO 4 4 2000 2000 HSO 4

63.9 mg NH 60.5 mg NH 1000 1000

0 0 (D)

(B)

NH

3

4

NO 5 4000 4 3 190 189 Time (s) 4 NO 4 SO 3000 2 ) 3000 4 cients of MA onto ammonium salts at 298 K.

ffi NH 4

2000 2000 SO 2 ) 59.8 mg NH 4 Electrostatic potential maps for ammonium salts. 1000 1000 58.2 mg (NH Fig. 5. (C) (A) 0 0 Cl (NH 4 nto ammonium salts at 298 K. . Typical observed uptake coefficients of MA o

0.010 0.005 0.000 0.010 0.005 0.000

obs g Fig. 4 Electrostatic potential maps for ammonium salts. Typical observed uptake coe

NH Fig. 5. Fig. 4. 23 24 25 26 27 28 29 30 31 32 33 34 35 37 39 40 41 42 43 44 45 46 47 38 36

Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

3 NO 1800 4 NH (KJ/mol) + 4 1600 4 SO 2 ) 4 1400 -6 y=-3.71E-3+7.21E R=0.9999 (NH

1200

6 191 cients of MA onto ammonium salts and the electro- . ffi + 4 1000 4 Cl 4 . NH HSO + 4 4 800 NH NH Electrostatic potential of H atom in 600

0.020 0.015 0.010 0.005 0.000

nt e i c i ff e o c e k a t p U ts of MA onto ammonium salts and the Relationship between uptake coefficien Relationship between uptake coe

Fig. 6. electrostatic potential of H atom in NH Fig. 6. static potential of H atom in NH 48 49 50