1. Thermal-Denuder + AMS Measurements
Alex Huffman, Ingrid Ulbrich,
and Jose-Luis Jimenez
University of Colorado-Boulder
FLAME Meeting at CSU, 22-Feb-07

2. Rapid Chemistry + Volatility Analysis
Ambient
Air
HR-ToF-AMS
Thermal
Denuder
Mexico City 2006
Huffman et al.

3. Thermal Denuder + HR-ToF-AMS
A. Huffman et al., CU Boulder

4. Evaporation in a Thermal Denuder
Simple Model: 1) allow a (400 nm radius) particle to evaporate for 9 seconds
2) ignore diffusion (influence gets included w/ specified p0(T))
3) assume particle composed of 1-7 individual components
(each with unique DHvap and p0(T))
25 °C
100 °C
200 °C
From Chris Cappa, NOAA ESRL

5. Evaporation in a Thermal Denuder
● Model cannot reproduce observations using only one or two components with reasonable thermodynamics
Huffman et al.
DH = 100 kJ/mol
DH = 30 kJ/mol
DH = 10 kJ/mol
DH = 5 kJ/mol
● However, observations can be nearly matched using just a single component (even better for two) in a highly parameterized way
Chris Cappa, NOAA,
Paul Ziemann (UCR)
Alex Huffman (CU)

6. Evaporation in a Thermal Denuder
88 kJ/mol < DHvap < 156 kJ/mol
● Observed trends in organics can be (potentially) explained via a multi-component “liquid-like” model with reasonable thermodynamics
Huffman et al.
7-component
● No unique solution
● Necessary to have non-volatile component
Chris Cappa, NOAA,
Paul Ziemann (UCR)
Alex Huffman (CU)

7. Montana TD-AMS

8. Montana TD-AMS II
T50

9. Distribution of Volatilities (T50)
Urban HOA
Urban OOA
Volatility of Urban POA/HOA is big issue => also for BBOA

10. Volatility vs. Organic Fraction I

11. Volatility vs. Organic Fraction II

12. Character of Organic Spectra
Hydrocarbon-Like OA
HOA
Oxygenated OA
OOA
Montana Biomass OA
BBOA

13. Volatility vs. Organic Spectrum

14. Volatility vs. Organic Spectrum II

15. Summary of TD-AMS TD-AMS: chemically resolved volatility
Interpret ~ distribution of Pvap and DHvap
Smoke volatility varied widely
Most were more volatile than urban aerosols
Volatility is correlated w/ chemical character
Organic fraction
Character of the organic spectrum
Spectra change with temperature
Ongoing analysis