 |
| Titel |
Towards the identification of molecular constituents associated with the surfaces of isoprene-derived secondary organic aerosol (SOA) particles |
| VerfasserIn |
C. J. Ebben, B. F. Strick, M. A. Upshur, H. M. Chase, J. L. Achtyl, R. J. Thomson, F. M. Geiger |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 5 ; Nr. 14, no. 5 (2014-03-05), S.2303-2314 |
| Datensatznummer |
250118460
|
| Publikation (Nr.) |
 copernicus.org/acp-14-2303-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| Secondary organic aerosol (SOA) particle formation ranks among the least understood chemical processes in
the atmosphere, rooted in part in the lack of knowledge about chemical
composition and structure at the particle surface, and little availability of
reference compounds needed for benchmarking and chemical identification in
pure and homogenous form. Here, we synthesize and characterize SOA particle
constituents consisting of the isoprene oxidation products α-,
δ-, and cis- and trans-β-IEPOX (isoprene
epoxide), as well as syn- and anti-2-methyltetraol. Paying particular
attention to their phase state (condensed vs. vapor), we carry out a
surface-specific and orientationally selective chemical analysis by
vibrational sum frequency generation (SFG) spectroscopy of these compounds in
contact with a fused silica window. Comparison to the vibrational SFG spectra
of synthetic isoprene-derived SOA particle material prepared at the Harvard
Environmental Chamber yields a plausible match with
trans-β-IEPOX, suggesting it is an abundant species on their
surfaces, while the other species studied here, if present, appear to be SFG
inactive and thus likely to be localized in a centrosymmetric environment,
e.g., the particle bulk. No match is found for authentic SOA particle material
collected at the site of the Amazonian Aerosol Characterization
Experiment (AMAZE-08) with the surface SFG spectra of the
compounds surveyed here, yet we cannot rule out this mismatch being
attributable to differences in molecular orientation. The implications of
our findings for SOA formation are discussed in the context of condensational
particle growth and reactivity. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|