Interim Proposal for Molecular Beam Studies of Surfactants in Sulfuric Acid Aerosols: Comparisons Between Hydrocarbon and Fluorocarbon Alcohols
Abstract
Heterogeneous reactions of gas phase molecules with aqueous sulfuric acid aerosols play a significant role in the destruction of ozone in the stratosphere. These processes include the acid-catalyzed reactions of HCI and HBr with CIONO2 (BrONO2) and HOCI (HOBr) to generate photoactive halogen molecules, particularly in colder regions of the stratosphere where they are more soluble in the water-rich aerosols. Our objective is to determine the mechanisms and rate-limiting steps of reactions of these atmospheric gases with these supercooled sulfuric acid droplets. By employing molecular beam scattering techniques, we probe the nature of the initial gas-sulfuric acid collision and the immediate fate of HCI and HBr molecules trapped at the acid's surface as they either desorb into the gas phase or react in the interfacial or bulk regions of the aerosol. In this interim grant period, we have explored the ability of organic molecules dissolved in sulfuric acid to form surface films that impede gas uptake and thereby reduce the rates of heterogeneous reactions in the acid. These surface-active organic molecules are found naturally in the upper troposphere and tropopause and may be produced in the exhaust of jet aircraft. We have so far investigate the entry of trifluoroethanol and HCI gas molecules into bare sulfuric acid and acid coated with butanol, dodecanol, and hexadecanol. These hydrocarbon surfactants have kept us busy, and we have not yet compared them with fluorocarbon ones.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 2003
- Accession Number
- ADA414462
Entities
People
- Gilbert M. Nathanson