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Title: Growth of Ammonium Bisulfate Clusters by Adsorption of Oxygenated Organic Molecules

Quantum chemical calculations were employed to model the interactions of the [(NH4+)4(HSO4-)4] ammonium bisulfate cluster with one or more molecular products of monoterpene oxidation. A strong interaction was found between the bisulfate ion of the cluster and a carboxylic acid, aldehyde or ketone functionality of the organic molecule. Free energies of adsorption for carboxylic acids were in the -70 to -73 kJ/mol range, while those for aldehydes and ketones were in the -46 to -50 kJ/mol range. These values suggest that a small ambient ammonium bisulfate cluster, such as the [(NH4+)4(SO4-)4] cluster, is able to adsorb an oxygenated organic molecule. Although adsorption of the first molecule is highly favorable, adsorption of subsequent molecules is not, suggesting that sustained uptake of organic molecules does not occur, and thus is not a pathway for continuing growth of the cluster. This result is consistent with ambient measurements showing that particles below ~1 nm grow slowly, while those above 1 nm grow at an increasing rate presumably due to a lower surface energy barrier enabling the uptake of organic molecules. This work provides insight into the molecular level interactions which affect sustained cluster growth by uptake of organic molecules.
Authors:
 [1] ;  [2] ;  [3] ;  [1]
  1. Univ. of Delaware, Newark, DE (United States)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
  3. Univ. of California, Davis, CA (United States)
Publication Date:
OSTI Identifier:
1239790
Report Number(s):
BNL--111698-2015-JA
Journal ID: ISSN 1089-5639; R&D Project: 2016-BNL-EE630EECA-Budg; KP1701000
Grant/Contract Number:
SC0012704; DE-AC02- 98CH10886
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory
Additional Journal Information:
Journal Volume: 119; Journal Issue: 45; Journal ID: ISSN 1089-5639
Publisher:
American Chemical Society
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES