Summary of Recent Work on the Fragmentation Table & Oven Aerodyne

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1 Summary of Recent Work on the Fragmentation Table & Oven Aerodyne Tim Onasch - Aerodyne Boulder AMS Users Mini Meeting University of Colorado March 9-, 23 Fragmentation Waves AMS Users Meeting Boulder, CO 339

2 Fragmentation Waves Air beam Oxygen 6 CO2 Relative Humidity gas phase water Water sulfate, carboxylic acids, particulate Ammonium 2 Nitrate Sulphate Organic Potassium Others ±.2 Air ±.2 Water.4 ±. Ammonium.32 ±.4 Nitrate.37 ±.8 Sulphate.463 ±. Organics 2.7 ±.3 Chloride.26 ± Ann Middlebrook and Brendan Matthew s Fragmentation Chart frag_wave m/z entry suggested/corrected entry problem/question Response Corrected Entry (2/7/3) I agree. Minor note: I am changing the.38 to air 7.38*frag_air[6],frag_RH[7].38*frag_O6[6],frag_RH[7] frag_air[6] includes.39*frag_o6[6],frag_rh[7] frag_rh[6].39 to agree with NIST isotope data. 8.2*frag_air[6],frag_RH[8].2*frag_O6[6],frag_RH[8] frag_air[7] includes frag_rh[7] I agree..2*frag_o6[6],frag_rh[8] Definitely more careful analysis needs to be done on this subject. For now, 28 is by far the largest contribution from airbeam, and thus should be 28 decreases during pumpdown expected have the lowest percent contribution from maybe base on 32? (potential contamination) contamination. On the other hand, this is very experiment dependent, as we have explosive data that shows large increases in 32 (for example) above and beyond air. 32,-frag_sulphate[32], ,-frag_sulphate[32] frag_nitrate[32] is non-zero Good catch! 32,-frag_sulphate[32],-frag_nitrate[32] frag_nitrate[32] You are correct that Ar is ~.9*air, ~.2*N2, and the last part is that N2(28) is ~87% of the total Why? Ar is.9*air or 4.9*.2*.3*frag_air[28] nitrogen signal (4,28,29). Based on NIST numbers, I.9*.28*.44*frag_air[28].2*N2 suggest we use the following:.9*.28*.44*frag_air[28]. additional comments could be a problem for aircraft instruments What about relative IEs? Empirical to date, as their either appears to be an instrument dependent issue here, or we have not RH 6.4*frag_RH[8] Empirical fragmentation? Frank's carefully paid attention to ambient RH conditions. value =.9 Frank's numbers come from the standard NIST MS data base. (amu 6=.9%, 7=2.2%, 8=%, 9=.%, and 2=.3%).4*frag_RH[8] Empirical - need to measure 7.2*frag_RH[8] Empirical fragmentation? Frank's Same. value =.2.2*frag_RH[8] Empirical - need to measure Will vary with ambient RH. This is where we define the amount of water coming from gas phase (ambient RH). If we set this number correct, all other frag_rh 8.*frag_air[28] Empirical for dataset, may vary with ambient RH contributions are determined (though more work needs to be done to ensure that we have the correct fragmentation patterns for the rest of frag_rh, as you.*frag_air[28] point out above). James is working on changing his code to allow for ambient RH data (from RH monitors being built into the new instruments) to be accounted for in the fragmentation waves. The measurements will be used to set the factor (currently set to.) for each MS in an experiment. Empirical - need to measure. Eventually include ambient RH measurements..682*frag_rh[8],.2*.3*fr 9 ag_rh[8] Isotope + fragmentation? Fragmentation should include isotope. Two points here. First, there are two contributions of signal to amu=9 from water. The first is the isotope fraction from H2O fragment (NIST value is.69, compared with our current.682). The second contribution is from OH fragment (NIST value is.69*frag_rh[8],.2*frag_rh[7.2). Our current misleading issue is that right ] now, rather than defining the OH isotope contribution from frag_rh[7], we are defining it again from frag_rh[8]. Thus, I suggest we change the element to the following:.69*frag_rh[8],.2*frag_rh[7]. O6 6.33*frag_air[4] Empirical for instrument You are correct, as far as we know..33*frag_air[4] Empirical - need to measure 2

3 CO *.6*.2*frag_air[28] Currently, N2 (28) is our measure of "air". CO2 44 will definitely vary with ambient CO2. James is Why? CO2 is about 37 ppm in working on incorporating ambient CO2 (and RH data, air (not N2). May vary w/ ambient.37*.28*.44*frag_air[28] see above) data into the fragmentation waves via the CO2 factor in frag_co2[44] to account for ambient CO2 changes. Assumes CO2 is 37 ppm. Eventually include ambient CO2 measurements. What about relative IEs? water 6.4*frag_RH[8] Note: Water is defined using the same fragmentation patterns as was done above for RH. Thus we have Empirical fragmentation? Frank's the same issues as discussed above. Note that you.4*frag_water[8] value =.9 have incorrectly typed in frag_rh[8] (rather than the correct frag_water[8]) for water (amu=6 and 7). Empirical - need to measure 7.2*frag_RH[8] Empirical fragmentation? Frank's value =.2 same as above.2*frag_water[8] Empirical - need to measure.682*frag_water[8],.2*.3 9 *frag_water[8] Isotope + fragmentation? Fragmentation should include isotope. See frag_rh[9] response above. I suggest we make.69*frag_water[8],.2*frag_wat the same change here as discussed above. er[7] NH4.*frag_NH4[6] 6,-frag_water[6],-frag_air[6],- 6,-frag_water[6],-frag_air[6],- 6 frag_so3[6],-frag_organic[6] frag_sulphate[6],-frag_organic[6] *.*frag_nh4[6],frag_nh4_7[ 7 frag_nh4_7[7] 7] Empirical fragmentation? Frank's The.*frag_NH4[6] comes from the NIST average value =.8 (assumes MS. (Peak intensities: amu 4=2.2, =7., 6=8,.*frag_NH4[6] ammonium, not amine) 7=, 8=.4). I agree. We should stick with using "frag_sulfate" in 6,-frag_water[6],-frag_air[6],- make formula more general all cases in the fragmentation waves. frag_sulphate[6],-frag_organic[6] Yes. The zero was placed in the element so that if we need to define the ammonium 7 based solely on NH4[6] (because amu=7 signal is drastically affected by large amounts of water, for example), its easier to remove the zero rather than retype the full "" placeholder? element. Again, I am not a fan of having extra, unnecessary math in the fragment waves, but there are many times that NH4[7] is not usable and thus this is a good reminder/simple way of changing between the two approaches. Empirical - need to measure NH4_7 7 make formula more general, could put entry in NH4 wave 7,-frag_water[7],-frag_air[7],- frag_so3[7],-frag_organic[7] 7,-frag_water[7],-frag_air[7],- frag_sulphate[7],-frag_organic[7] I agree. We should stick with using "frag_sulfate" in 7,-frag_water[7],-frag_air[7],- all cases in the fragmentation waves. frag_sulphate[7],-frag_organic[7] nitrate 4.4*frag_nitrate[3],.4*frag_nit rate[46] Empirical fragmentation? Frank's value =.42 Empirical to date..4*frag_nitrate[3],.4*frag_nitrate[46 Empirical - need to ] measure 47.*.443*frag_nitrate[46].443*frag_nitrate[46] Typo? Isotope only, Frank's value =.4 (isotope only).443*frag_nitrate[46] Empirical? Could be just isotope. Need to measure 63 2*.2*frag_nitrate[3],.2*fra g_nitrate[46] Typo? Empirical fragmentation? Frank's value =.49 Empirical to date..2*frag_nitrate[3],.2*frag_nitrate[ Empirical - need to 46] measure sulphate 6 frag_so3[6] frag_so3[6],frag_h2so4[6] make formula more general why? I am not a big fan of using zeros and/or undefined/unnecssary variables. 7 frag_so3[7] frag_so3[7],frag_h2so4[7] make formula more general I did check it out, and the fragmentation waves will work either way, though I will argue that there is no point to make the formula "more general". The frag_sulfate wave can be changed if we decide in the future to include H2SO4 contributions to these amu's. 8 frag_so3[8] frag_so3[8],frag_h2so4[8] make formula more general 9 frag_so3[9] frag_so3[9],frag_h2so4[9] make formula more general 2 frag_so3[2] frag_so3[2],frag_h2so4[2] make formula more general 8 frag_h2so4[8] frag_so3[8],frag_h2so4[8] make formula more general 83 frag_h2so4[83] frag_so3[83],frag_h2so4[83] make formula more general 8 frag_h2so4[8] frag_so3[8],frag_h2so4[8] make formula more general I will try calculating H2SO4 all The H2SO4/SO3 fragmentation patterns were derived from indepth investigations of pure H2SO4 aerosol Don't understand what's going on MS taken by Jay Slowik at BC and ammonium here. Need H2SO4/SO3 sulfate aerosol at ARI. More work needs to be done fragmentation info. on the ammonium sulfate aerosol. Jay is still working on the H2SO4 particles. the total sulphate by subtracting out the organic contributions and use the ambient fragmentation pattern to determine frag_h2so4 and frag_so3. SO3 all Differences in fragmentation patterns are believed to be due to the different molecules that vaporize from the oven (more H2SO4 from pure H2SO4, and more Don't understand what's going on SO2/SO3 from ammonium sulfate). We started with here. Need H2SO4/SO3 the pure H2SO4 spectra and assigned peak fragment fragmentation info. ions and intensities. We then compared this spectra (frag_h2so4) with the MS for ammonium sulfate and derived the frag_so3 wave. 3

4 Assumes H2O/CO2 - need to.77*frag_organic[44] (variable organic 8 *frag_organic[44] account for H2O fragmentation depending on ) (.77=/(+.2+.4)) Isotope + fragmentation?.682*frag_water[8],.2*.3 9 Fragmentation should include *frag_water[8] isotope. potential organic contribution - 28 nothing may contain organic? needs to be investigated potential amine contribution *frag_organic[29] may be impossible! needs to be investigated potential alcohol contribution - 3 nothing 3,-frag_nitrate[3] needs to be investigated either.*frag_organic[27],.*frag_organi potential organic contribution - 39 nothing c[] or needs to be investigated.*frag_organic[2],.*frag_organi c[3] may be characteristic of amines - potential amine contribution needs to be investigated needs to be investigated I agree, though we have to be careful here as carbonates and other compounds may give CO2 and Needs further no water. This number is still in flux and we need to.77*frag_organic[44] investigation. look at data sets much harder to get more information on this. See discussion of amu=9 for frag_rh above. Note.69*frag_organic[8],.2*frag_or that you have incorrectly written "frag_water" here ganic[7] when it is "frag_organic" in the frag waves. Needs further C2H4, CO, N2 Need to do more here. investigation. Needs further C2H6, CH2O, NO. Need tod do more here. investigation. Needs further CHN. Need to do more here. investigation. Possible, however there are several points we need to fully consider before we attempt to estimate the organic contribution to mass 39. () The organic component to each amu reaches a maximum, around Needs further carbon 3-4, amu=43-7 depending upon delta series, investigation. and thus we cannot depend upon our estimate of.*(amu-4)+.*(amu+4). (2) There are very few typical organic fragments at mass=39. Needs further Yes, I agree. investigation. potassium ,-frag_organic[39] see frag_organic[39] Potassium is surface ionized and thus cannot be quantified currently. Caught many typo s. Corrected several important incorrect references. Better understanding of fragments chosen and source of each factor. Filter measurements 4

5 Mass Concentration (µg m -3 ) Mass Concentration (µg m -3 ) Airbeam, O6, RH, and CO2 Filter, Filter, Filter 4:4 PM 3/3/23 4: PM : PM : PM Date and Time Water Ammonium Nitrate Sulphate Organics Chloride Water Ammonium Nitrate Sulphate Organics Chloride Top mass loading plot is the original (straight from template). Changed frag_o6[6] from.33*frag_air[4] to.289*frag_air[4]. Changed frag_rh[8] from.*frag_air[28] to.*frag_air[28]. Set CO2? 4:4 PM 3/3/23 4: PM : PM : PM Date and Time Filter Sample Carbons -6 Carbons -4 Equivalent Mass Conc % 3.% Runs Averaged: 97 to 94 (3/3/23 6:34 to 7:7) Signal Intensity Mass / amu -2 Particle Composition ( µg/m3) -43.% Water % Ammonium % Nitrate % Sulphate % Organics.2 -.6% Chloride (NH4)meas/(NH4)expt = Number of Carbons. Others.29 ±.8 Air 97. ±.7 Water -.33 ±.2 Ammonium.443 ±. Nitrate.4 ±. Sulphate.99 ±. Organics. ±. Chloride -.99 ± Carbons % Delta relative Signal AMU NaN : NaN : Inf.72 : : 8.2 : : 2.84 : Air Water Ammonium Nitrate Sulphate Chloride Others.29 ±.8 Air 97. ±.7 Water -.33 ±.2 Ammonium.443 ±. Nitrate.4 ±. Sulphate.99 ±. Organics. ±. Chloride -.99 ±. -4 Largest two organic peaks are 44 and M/Z = 27 appears to be leakage from m/z = 28. M/Z = 44 suggests that CO2 concentration is incorrect and needs adjusting. Over all, very clean!

6 Relative Humidity Questions: How to determine RH in spectra? What are the RH_8/7 and RH_8/6 ratios for gas phase water? How do these ratios change with ambient RH? Filter samples at different RH Mass Concentration (µg m -3 ) 2 - Water Ammonium Nitrate Sulphate Organics Chloride 9:3 AM 3//23 : AM :3 AM : AM Date and Time Excess RH is observed as condensed phase water, as sulfate and organic water contributions are tied to m/z s 48 and 64, and 44, respectively. Use low RH filter to define zero RH, and compare high RH filter sample to estimate water fragmentation pattern. 6

7 RH water fragmentation wave... Others.79 ±. Air 38 ±.7 Water.287 ±.2 Ammonium -.68 ±. Nitrate.229 ±. Sulphate.73 ±. Organics.8 ±. Chloride -.64 ±.... Air 39 ±.2 Water.49 ±. Ammonium -.27 ±.3 Nitrate.892 ±.2 Sulphate ±.4 Organics -.8 ±. Chloride. ±.2 Others.4 ± Observations and Comparisons: m/z 8/7 ratio =.26 m/z 8/6 ratio = -. Frank Drewnick:.2.4 NIST MS:.22.9 Ratio s to use: Ammonium Nitrate Particles Questions: What are the NH4_7/6 and NO3_46/3 ratios for pure ammonium nitrate particles? How do these ratios change with oven temperature? 7

8 Ammonium Nitrate Fragmentation Pattern Others.69 ±.9 Air 3. ±.4 Water.2 ±. Ammonium 9. ±. Nitrate 24.4 ±.3 Sulphate.47 ±.2 Organics -.27 ±. Chloride.684 ± Experiment (/2/3 ) Oven temperature = 627oC 2nm monodisperse AN Equivalent Mass Conc... Runs Averaged: 2 to (/2/23 :6 to :9) Carbons -4 Carbons -6 Carbons % 4.6% % Delta Signal Intensity relative Signal Mass / amu 43 Number of Carbons AMU. : :.3.76 : NaN : NaN : Inf : NaN : NaN 2 7 Particle Composition (µg/m3).2% Water % Ammonium % Nitrate % Sulphate % Organics.79.2% Chloride.4497 (NH4)meas/(NH4)expt =. 8

9 Another look at the NO3 and NH4 major peak ratios oven (oc) raito NO3 46/3 =.22 +/-.4 Oven (oc) Ratio NH4 7/6 =.28 +/-. Not included Mass Concentration (µg m -3 ) NO3_46 NO3_3 Mass Concentration (µg m -3 ) NH4_6 NH4_7 3: PM /2/23 3: PM 3:2 PM 3:2 PM Date and Time 3: PM /2/23 Date and Time 3:2 PM 3:3 PM Nitrate peaks appear highly correlated; ammonium peaks not as well correlated. Large variation in ratios, not obviously related to oven temperature change. Ammonium 7/6 ratio variations appear mainly to be due to noise levels in the MS NH4 7/6 ratio Mass Conc. (µg m -3 ) NH4 7/6 =.3 +/-.3 4/2/2 //2 //2 /2/2 /3/2 Date and Time Not included NH4_6 NH4_7.. 2 Noise on m/z=4 causes over estimate of air signal at 4 and Air 7 ± Water.7 ± 3 Ammonium 2.69 ± Nitrate 4.73 ±.3 Sulphate.42 ±.3 Organics -.28 ±.6 Chloride -.4 ±.8 Others -.43 ± Air 63 ± 7 Water 2.2 ± 3 Ammonium 6.6 ± Nitrate 33 ± Sulphate.68 ±.2 Organics.839 ±.6 Chloride.38 ±.7 Others ± Noise on m/z=7 causes under estimate of signal

10 Change of ratios with oven temperature 4. NH4 7/6 ratio NO3 46/3 ratio Oven Temperature (oc) The ratios decrease with increasing oven temperature This is expected, as increased internal energy may cause greater fragmentation AN as function of oven temperature oven (oc) Part. conc. (cm -3 ) Mass Concentration (µg m -3 ) : PM 2/2/23 4:3 PM : PM :3 PM 6: PM 6:3 PM Date and Time CPC AMS Water Ammonium Nitrate Sulphate Organics Chloride

11 Succinic Acid oven (oc) Mass Concentration (µg m -3 ) Water Ammonium Nitrate Sulphate Organics Chloride CPC 2 6: PM 2/26/23 6: PM 6:3 PM 6:4 PM 7: PM Date and Time Summary Recent data indicates: NH4 7/6 ~.46 NO3 46/3 ~.2 Both have a temperature dependence (decreases ratio with increasing oven temperature). Phil Silva s data indicates: NH4 7/6 ~. NO3 46/3 ~.6 NIST: NH4 7/6 =.2 NO3 46/3 =? decent estimate at normal operating oven temperatures. need to obtain MS of nitric acid.

12 Ammonium vs water content Equivalent Mass Conc... Runs Averaged: 64 to 6 (/22/2 7:3 to 7:3) = 2 / = 3 / 27 start/max Equivalent Mass Conc Carbons -4 Carbons -6 Carbons 7- Carbons -4 Carbons -6 Carbons % 8.7% 3.% Delta Signal Intensity relative Signal %.% 2.4% Delta Signal Intensity relative Signal Mass / amu Number of Carbons AMU. : :.9.82 : :.79 : :.46 :.8 Run: 862 (6/4/2 9:3) Mass / amu Number of Carbons = 2 29 / 29 = 27 / 69 start/max Particle Composition (µg/m3) 9.6% Water.77 % Ammonium % Nitrate % Sulphate % Organics % Chloride (NH4)meas/(NH4)expt = AMU. : : : :.7 :.2 :.3 : Particle Composition (µg/m3) 72.2% Water % Ammonium % Nitrate % Sulphate % Organics.49 % Chloride (NH4)meas/(NH4)expt =.494 NH4 7/6 Ratio Water content on Particles Water content does not affect our ability to calculate ammonium! 3 4 Oven Temperature Experiments: Calibration Channel (Volts) : PM /4/ : PM 4: PM : PM 6: PM 7: PM 8: PM Temperature (oc) Heater Temp (Celsius) CurveFit poly 4, temp_tim /X=watts_tim /D fit_temp_tim= poly(w_coef,x) W_coef={34.33,2.6,-8.487,.23837} V_chisq= ; V_npnts= 9; V_numNaNs= ; V_numINFs= ; W_sigma={.8,4.9,.636,.24} Coefficient values ± one standard deviation K = ±.8 K = 2.6 ± 4.9 K2 = ±.636 K3 = ±.24 Ionizer Off Ionizer On at 2. ma Tim (ionizer =.2mA) Fit Date/Time Heater Power (Watts) 2

13 Greater Sensitivity to Refractory Compounds at Higher Oven Temperatures Comparison of Oven Temperatures o C 87 o C

14 Ammonium Chloride Obtain method for categorizing chloride sources. What is the ratio between m/z = 3 and 36 for ammonium chloride? NH 4 Cl (~6 o C) Equivalent Mass Conc... Runs Averaged: 6 to 79 (/2/23 6:2 to 6:3) = 2 29 / 29 = 3 / 27 start/max Carbons -4 Carbons %.4% Signal Intensity Mass / amu Number of Carbons Particle Composition (µg/m3) -3.6% Water % Ammonium 8.9.7% Nitrate % Sulphate % Organics % Chloride (NH4)meas/(NH4)expt =.33 Carbons % Delta relative Signal AMU. : :.6. : NaN : NaN : NaN : NaN : Inf 4

15 Nan Nan NH 4 Cl (~ o C) Equivalent Mass Conc... Runs Averaged: 3 to 63 (/2/23 6:9 to 6:9) = 2 29 / 29 = 3 / 4 start/max Mass / amu Carbons -4 Carbons % 4.3% Signal Intensity Number of Carbons 2 Particle Composition (µg/m3) -.9% Water % Ammonium % Nitrate % Sulphate % Organics % Chloride 4.86 (NH4)meas/(NH4)expt =.29 Carbons % Delta relative Signal AMU. : :.23.2 : : : : :.63 Fragmentation Patterns for Ammonium Chloride Looking to obtain new chloride fragmentation waves for () HCl and (2) Cl Cold Oven (~6 o C) Hot Oven (~ o C) Air Water. Ammonium Nitrate Sulphate Air Water. 6. Ammonium Nitrate Sulphate Chloride Chlorine Fragmentation Pattern: Low Temperature: High Temperature: Chloride 38/ / /

16 Formula Mass H# CH C2H C3H C4H CH 7.86 C6H C7H C8H C9H CH CH C2H C3H C4H CH C6H C7H C8H C9H C2H C2H C22H HC mass scale Delta 2 Mass scale difference H2ON2 CnH2n+2 (delta 2) exact mass scale Zn C8HO3 AMU W Pyrene Chrysene 2 Pb Hg 2 Pentacene Antanthrene 3 6

1. Load Data Computing Requirements: 1 GB RAM is best. Need Igor 4.07 at least.

1. Load Data Computing Requirements: 1 GB RAM is best. Need Igor 4.07 at least. Data Analysis Tutorial AMS Users Meeting 10/9/2004-10/11/2004 Outline: 1. Load Data 2. Check Diagnostics 3. Check Mass Trends 4. TOF Image Plot 5. Check Average Mass Spec 6. Corrections Airbeam correction