Date of Award

2019

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Chemistry

Department

Chemistry

First Advisor

William B. Euler

Abstract

Chapter 1 of this dissertation is an investigation of rhodamine 560 (Rh560), a cationic dye similar to the well-studied rhodamine 6G (Rh6G). The spectral properties of Rh560 and Rh6G have similar changes as a function of thickness. At low surface coverage the spectra indicate monomers, at 1-2 monolayers dimers dominate, and thicker films show larger aggregates. The difference between Rh6G and Rh560 is that the transition from monomer to dimer occurs at different thickness, ~1.2 nm for Rh6G and ~0.5 nm for Rh560. This difference is accounted for by the molecular size. Chapters 2 and 3 describe photophysical investigations of the zwitterionic dyes, Sulforhodamine 640 (SRh640, Chapter 2) and sulforhodamine B (SRhB, chapter 3). The charge appears to have little effect as the thin film behavior in the zwitterions. As with Rh6G and Rh560, the films change from monomer to dimer to aggregate. The monomer to dimer transition occurs at ~1 nm for SRh640 and at ~1.5 nm for SRhB, consistent with their molecular sizes.

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