The AMS as a Single Particle Mass Spectrometer

Transcription

1 The AMS as a Single Particle Mass Spectrometer 9 th AMS User s Meeting (Eben s 5 th ) September 5-7, 28 University of Manchester Eben Cross

2 TIME SPENT OVER THE PAST 5 YEARS WORKING ON STUFF RELATED TO THE AMS ~ 16,9 hours JAMES CREATES A TOOL FOR THE INTERNET THAT ALLOWS YOU TO SEARCH THE ENTIRE WORLD RAMI WIDE BECOMES WEB... ITS A CALLED VERY JOOGLE SUCCESSFUL CUBISON WINS STAND TOUR UP DE FRANCE JAY COMEDIAN FOCUSES 4 YEARS WITH ON STRAIGHT THIS AN ACT TRACK THAT FOCUSES AND FIELD (WITH ON CAREER STUPID NO DRUGS!) AND AMERICAN SMASHES POLITICIANS THE WORLD RECORD DOUG WORSNOP IN THE 15M RUNS IN FOR THE PRESIDENT 28 GAMES HE WITH ALSO A BECOMES TIME OF 3:32 THE sproud OF THE UNITED STATES OF AMERICA AND FATHER OF 1 MINI-RAMI S WINS (THANKS [Jay s TO real HIS 15 WISE m time CHOICE is 4:5 OF s] A RUNNING BUILDS MATE INTERNET CAMERON 2 (BY MARTIN) HAND) MAGIC CONVERTER BOX TAKE AMS-TIME AND SPEND IT ON SOMETHING ELSE... TIM STEPS UP HIS TENNIS GAME AND BEOMES THE WORLD S NUMBER ONE BEATING NADAL IN THE 28 OLYMPICS FOR THE GOLD

3 What you are about to see ATOFMS vs LS-C-ToF-AMS [Schematic Battle] Measuring particle time-of-flight dva Measuring ions (one particle at a time) LS-C-ToF-AMS Lab Stuff Field Stuff (MILAGRO 26)

4 Velocity dva Very precise measure of time-of-flight dva ~ 2 25 nm Ion signals... Detects refractory and non-refractory particles Good at seeing certain chemical components Not good at quantifying the chemical composition of the particles ATOFMS

5 Velocity dva VS Very precise measure of time-of-flight dva ~ 2 25 nm Ion signals... Detects refractory and non-refractory particles Good at seeing certain chemical components Not good at quantifying the chemical composition of the particles LS-C-ToF-AMS ATOFMS Less precise measure of time-of-flight dva (SP) ~ 2 7 nm Ion signals... Detects non-refractory particles t chopper Good at measuring non-refractory chemical composition t Vaporization Ion Detection

6 AMS distributions: Chopper-Chemical Ion Signal; Chopper-LS x1 3 x1 3 x1 3 x1 3 x1 3 x1 3 x1 3 x1 3 x1 3 ORGANIC MASS Sum of Scattered Light Signals x x1 3 x1 3 x1 3 x1 3 x1 3 x1 3 SCATTERED LIGHT Diameter < Optical size detection limit x x1-3 Particle Time-of-Flight (Chopper-Vaporizer(s)) Particle Time of Flight (Chopper-LS) Q

7 Velocity Calibration Specifics Time-of-Flight [Chopper - LS] Vaporization Ion Detection Time of DOP = 12 µs 3.x Velocity (m/s) Chopper to Ion Signal Chopper to (Ion Signal - 12us) Chopper - LS x1-3 1 Time-of-Flight [Chopper - Ion Signal] LS-C-ToF-AMS dva (nm) 5

8 Single Particle Mass and Scattered Light Distributions for DOS 'Org' ions per particle (IPP) MASS Integrated Light Scattering Signal LIGHT x dva (nm) 1 4 Moffet and Prather, Anal. Chem 25 2x dva (nm) Broad Laser Beam (LS-C-ToF-AMS) ~ 2.5 mm Tight Laser Beam (ATOFMS) ~.3 mm

9 MILAGRO Field Campaign Mexico City, Mexico March 26 T1 T 12,853 optically-triggered single particle mass spectra March 27, 28 March 3, 28 5,542 (43%) particles were vaporized and ionized during the saving interval. Megacity Initiative: Local and Global Research Observations

10 What do we get? Bulk ensemble average size & composition AND single particle size and composition Information about the mixing state Identify chemically distinct types of particles Information about atmospheric processing Influence of photochemistry on the single particle composition: NH4NO3 and OOA Source identification Contributions from biomass burning?? In-plume processing (SO2 from Petrochemical Industries)

11 BULK ENSEMBLE NON-REFRACTORY CHEMICAL COMPOSITION Preliminary PMF Components (Thanks to Manjula and Tim) Typical Frag Components AMS - Single particle chemical composition measured with the same instrument at the same time

12 Coincident Particles: Evidence of External Mixing 6x1 3 Light Scattering Signal LS Signal Chemical Ion Signal 5x Total Ion Signal x1-3 Time-of-Flight (s)

13 Coincident Particles: Evidence of External Mixing particle #1 6x1 3 particle # LS Signal Light Scattering Signal 2 Chemical Ion Signal Chemical Signal (arbitrary units) 5x Organic Total Ion Signal Time-of-Flight (s) particle #1 3 particle #2 4x m/z

14 Coincident Particles: Evidence of External Mixing particle #1 6x1 3 particle # LS Signal Light Scattering Signal 2 Chemical Ion Signal Chemical Signal (arbitrary units) 5x Organic Nitrate Sulfate Ammonium Chloride Total Ion Signal 1 2 Time-of-Flight (s) particle #1 3 particle #2 4x m/z

15 Single Particle Mass Fractions

16 Single Particles Containing HOA Mass NOTE Colored by OOA content

17 Single Particles Containing HOA Mass NOTE Colored by OOA content Single Particles without HOA Mass NOTE colored by (NH4)2SO4 content

18 Single Particle Chloride / HOA content Single Particle Chloride / OOA content

19 Single Particle Chloride / NH4NO3 content Single Particle Chloride / (NH4)2SO4 content

20 Quick Conclusions Chemically Distinct particle types identified with LS-C-ToF-AMS Insight into the condensation of NH4NO3 onto all single particles in the mid-late morning Continued OOA condensation during the afternoon Interesting high chloride content particles...needs more attention Need more single particle statistics! MILAGRO LS-C-ToF-AMS [13,p/3 days] = 18 p/hr hit rate [Accumulation size mode] MILAGRO ATOFMS T [1e6p/4 weeks] = ~ 15 p/hr [Accumulation and supermicron size modes] J. Kimmel TOMORROW improving the single particle duty cycle x 1 Ultimately, BOTH ATOFMS and AMS need to be used.

21 The End AMS TANK