Date of Award


Document Type

Restricted Thesis

Terms of Use

© 2000 Laura Pomerance. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts


Physics & Astronomy Department

First Advisor

Peter J. Collings


Resonance light scattering (RLS) permits precise and sensitive measurement of the size, shape and aggregate number of aggregated chromophores. However, interpretation of data is complicated by the fact that resonance scattering is reduced by absorption and vice versa. A technique is described which allows resonance extinction spectra to be separated into absorption and scattering components. Once correct values of absorption and scattering are known, the number of aggregates per monomer can be calculated. RLS, structure factors and dynamic scattering measurements are used to find the size, shape and aggregate number of tetrakis(4-sulfonatophenyl)porphine (H₂2 TPPS4⁻) aggregates formed in aqueous solutions of HCI and NaCl. The sizes, shapes and aggregate numbers of aggregates formed in HCI were not significantly different from those formed in NaCl. The aggregates were, within 5 to 15 percent error, 0.1 - 0.7 µm in length. Their aggregate numbers were on the order of 10⁵ - 10⁶ . These values are in agreement with literature and represent the most accurate measurements of H₂ TPPS4⁻ aggregates to date.