HR Clinic

Email announcing the Clinic (sent 30-Jan-2009)

Dear all,

We would like to announce a "clinic" for the analysis of high-resolution ToF-AMS data (also including unit-resolution analyses). The idea is to provide a forum to discuss the analysis of high-resolution spectra (PIKA) in detail, and also including other topics such as PMF, APES (elemental analysis) and also unit-resolution analysis (Squirrel) in a format for which we don't have time in the regular Users Meetings.

Doug Worsnop, Donna Sueper, James Allan, Manjula Canagaratna, Qi Zhang, Jesse Kroll, Pete DeCarlo, and Jose Jimenez will be there. Ingrid Ulbrich will be there at least during the PMF discussions. The format will be something like:

• first day with presentations of new features in PIKA and overview of analysis
• Users bring up problems or special cases they have encountered in their work
• Next several days: we intermittently break up and everyone works in their own data and we discuss interesting questions or problems as a group. We will also cover the other topics (PMF, APES, Squirrel) as appropriate, in a flexible way decided by consensus of the attendees.

The people who should attend are students, postdocs, and researchers who are currently actively analyzing high-resolution (and also unit-resolution) AMS data.

The location will be the University of Colorado-Boulder, and the dates will be Sat June 6 to Wed June 10, 2009. (Doug will only be present Sat to Mon, all the other organizers should be there the whole time). The dates are set because of Doug's other commitments.

Please let us know of your intention to attend, we are imagining about 25-30 people in attendance. Let us know if you have any suggestions about the content or the format.

Thanks,

-Jose et al.

Attendees

• Maximum is 38 attendees, due to the capacity of the rooms available. At present the meeting is FULL. Let us know if you would still like to attend and we'll see what we can do.

• Confirmed (39):
  • Doug Worsnop, Manjula Canagaratna, and Sally Ng (ARI)
  • Donna Sueper (ARI & Colorado)
  • James Allan, Rami Alfarra, and Niall Robinson (Manchester) (R)
  • Qi Zhang (SUNY-Albany)
  • Jesse Kroll (MIT)
  • Pete DeCarlo (PSI, Switzerland)
  • Mike Cubison, Sanna Saarikoski, Ken Docherty, Ingrid Ulbrich, Carly Robinson, Amber Ortega & Jose-Luis Jimenez (Colorado)
  • Steve Howell & Lindsey Shank (U. Hawaii)
  • Taehyoung Lee & Laurie Mack (Colorado State)
  • Puneet Chhabra & Jill Craven (Caltech) (R)
  • Lea Hildebrandt (Carnegie Mellon)
  • Samara Carbone and Risto Hillamo (FMI)
  • Qi Chen (Harvard)
  • Toshihide Hikida (Sanyu, Japan)
  • Yongjie Li (Hong Kong and Harvard)
  • Astrid Kiendler-Scharr and Christian (Juelich, Germany)
  • Jurgita Ovadnevaite (NIU Galway, Ireland)
  • Chiara Di Marco & Gavin Phillips (CEH, UK)
  • John Shilling (PNNL)
  • Hiroyuki Hagino (JARI, Japan Automobile Research Institute)
  • Akinori Takami (NIES, Japan) (R)
  • Dara Salcedo (U Morelos, Mexico)
  • Julia Schmale (MPI Mainz)
  • Manuel Dall'Osto (Galway)

• Tentative (1):
  • Delphine Farmer (Colorado)

Some topics for discussion

• General comments about the differences between unit resolution vs high resolution analysis

• Getting ready for HR fits

• • m/z parameters
    • How to evaluate when a set of m/z parameters is good enough
    • Discuss the newish idea that we should not use elemental values (N,C,O) for m/z fit
    • Discuss why/when open and closed have different parameters

• • Peak Shapes
    • Using the squirrel baseline instead of constant Pika-calculated baselines.
    • What the effect of having different left and right-side constant baselines (like for the air peaks)
    • Left- and right-side peak shape options from new panel
    • Discussion of the idea that the peak 'center' (as defined by the gaussian) may look different from the highest point because the peak may look more poisson-like.
    • Discuss the option to hold the peak center and/or peak width when finding peak shape.
    • Modifying the peak shape 'by hand'
    • Discussion of v/w mode peak width and peak shape results.

• • Fitting Masses
    • The selection of masses to fit
    • How to update the 'master' list of all possible species while retaining current mass selections
    • The 'name' of the element, vs it's likely chemical structure, i.e, we use CH3SO2 not CH2SO2H. We need to keep atoms together for APES code to correctly parse
    • Info about current default masses to fit (Users need more guidance to understand what is fit than beyond having to look through all 200+ masses, although it is ideal that users are aware of every peak that they fit).
    • Pete's suggestion - Redo the default such that fewer masses are fit, and users need to add masses if they appear.
    • How users can add HR spectra to the master list of all available HR fragments (and then to be shared with all).
    • Issues with doing HR fits past > 100 m/z.
    • Discuss future version whereby the fit isn't a 'gaussians multiplied by scalars' , rather the more intuitive 'Normalized' Peak Shape is fit via a look-up table.
    • The importance of fitting all peaks that appear, even if they don't appear in the raw difference spectra
    • Adding new families and the difference between the family concept and the HR batch/frag concept

• • Constrain Isotopes
    • When to not constrain, what does it mean when the sticks don't seem to perfectly match the isotopic ratio
    • Issues when dealing with trying to fit masses that are near x.5 m/z (Dara's question)
    • How constrained factor is generated (i.e. isotopic factor of a fragment with more than one C and one 13C atom)

• Evaluating Pika sticks for One 'Run'

• • Discuss the HR_PeakHeights_gr controls

• • Discuss the issue of the artifact of the widening the averaged raw spectra

• • The three diagnostic tools Steps 4A, 4B, 4C

• • Discuss how Pika/Igor can return a peak height that is < 0 (Igor 'feature')

• • General problems and issues when fitting the major air peaks.
    • How far from main air peak (in the m/z dimension) can we reliably fit?
    • What to do/how to think if there is saturation

• • How to evaluate when to add/remove masses
    • Looking at residuals to determine pHow to evaluate when to add/remove masses
    • Looking at related peaks (e.g. CxHy vs Cx+1Hy+2)
    • Discussion of how the HR stick Diff matrix saves sticks in columns, not m/z, so adding or removing one mass to fit means redoing everything.

• • Explain the difference between fitting the difference spectra and calculating the difference HR sticks via Open HR sticks - Closed HR sticks.

• • Explain why it is difficult to fit only one set of peaks centered at one integer; instead the default is to fit all integer masses because of isotope dependencies.

• HR Fit 'Errors'

• • Open - Closed Stick 'Counting' Errors (Pete's Errors)
  • Data - Fit 'Residual' Errors (Doug's Errors)
  • How to use mass accuracy to estimate uncertainty
  • Other sources of uncertainties

• Evaluating Pika sticks for a ToDo wave

• • How to evaluate when to add/remove masses
    • The use of the many parameter panel to identify when a mass needs to be added.
    • Looking at the time series of all chosen fitted masses for one integer m/z to see if there the masses are too close and the fits 'compensate' each other.
  • Doug's 5 panel graph
  • Discuss future incorporation of HR frag table, RIEs
    • How to access/dump the HR sticks.

• APES

• • Basis of elemental analysis (was very confusing in Users Meeting)
  • How to deal with CO2, CO, H2O et
  • Evaluation of the quality of N/C, S/C
  • Problems and doubts from users on how to use the software

• HR PMF

• • New features: seeds, bootstrapping
  • Examples of applications from users

• PIKA in Real Life (also discussed throughout and within other topics)

• • Users bring up doubts, examples of problems or unusual data and we discuss as a group
  • Donna: small variations in peak tails for Galway data. What is real vs other peaks, and how to deal with it?
  • Dara Salcedo: variations of peak shape with m/z across 10-300, and how to deal with it with current software

• HR-AMS Spectra database

• • Encourage users to give to Michael directly during meeting. Need peak shape function, sigma parameters, m/z cal.

• Squirrel Topics

• • Discussion of ICARRT formatting tool
  • Discussion of QuickView tool

Logistics

• Directions to CIRES in Boulder
• On Sat & Sun we will meet in Ekeley E1B20
• On Mon-Wed we will meet on Hale 260
  • Campus map link
• Jimenez Group Lab in Ekeley E150
• We will provide plug strips for laptops.
• Internet Access
  • Will be access for 40 individuals
  • June 3 thru June 12
  • Username: confams
  • Password: Will be given out at the conference
• Hotel Price Block
  • We have a pricing agreement with the Boulder Outlook Hotel link
  • Google Map of hotel link
  • You can reserve a room with one king bed or two twin beds for $98.00 per night by saying that you are with the HR-AMS Clinic
  • phone numbers: 303.443.3322/800.542.0304
  • Summer in Boulder is a busy time and the hotel does have the possibility of filling up. These rooms are not reserved and the sooner that a reservation can be made the better.
• Lunch and Coffe/Tea Places
  • Google Map link

Related Links

• ToF-AMS web page
• Squirrel Home Page
• Pika Home Page
• APES Wiki (Elemental Analysis of OA)
• AMS PMF Resources Page
• AMS Users Meetings
• High-resolution AMS database
• List of AMS papers
• AMS page at Aerodyne
• J-Group at CU-Boulder