Accession Number:

ADA379797

Title:

Molecular Beam Studies of Reactions between Stratospheric Gases and Supercooled Sulfuric Acid

Descriptive Note:

Final technical rept. 1 Apr 1996-31 Mar 1999

Corporate Author:

WISCONSIN UNIV-MADISON DEPT OF CHEMISTRY

Personal Author(s):

• Nathanson, Gilbert M.
• Morris, John R.
• Behr, Peter M.
• Antman, Melissa D.
• Splan, Jennifer

Report Date:

2000-04-15

Pagination or Media Count:

6.0

Abstract:

Sulfuric acid aerosols in the stratosphere contribute to the destruction of the ozone layer by converting inactive gases like HCl and HBr into molecules that fall apart into chlorine and bromine atoms, which catalytically destroy ozone. The first step in these reactions is the transport of gas phase HCl and HBr molecules through the surface of the liquid aerosol and into the acid, where they dissolve and dissociate. Our experiments show that the entry of HCl and HBr into sulfuric acid is often frustrated by immediate HCl and HBr evaporation from the surface of the acid. For mid-latitude stratospheric sulfuric acid, we find that only 11 of the HCl and 22 of the HBr molecules that strike the acid surface enter into the bulk. In contrast, water and nitric acid molecules enter the acid in nearly every collision. These measurements indicate that HCl and HBr are mostly unavailable for reaction with other solute molecules in mid-latitude aerosols because they evaporate from the acids surface faster than the can dissolve.

Descriptors:

• *OZONE DEPLETION
• AEROSOLS
• MOLECULAR BEAMS
• HYDROCHLORIC ACID
• CHLORINE
• BROMINE
• SULFURIC ACID
• STRATOSPHERE

Subject Categories:

• Physical Chemistry

Distribution Statement:

APPROVED FOR PUBLIC RELEASE