ORCID ID

https://orcid.org/0000-0001-7581-8729

Date Awarded

2020

Document Type

Thesis

Degree Name

Master of Science (M.Sc.)

Department

Chemistry

Advisor

Kristen Wustholz

Committee Member

Nathan Kidwell

Committee Member

William McNamara

Abstract

The impact of molecular aggregation on the photophysics of eosin y adsorbed to TiO2 was investigated using diffuse reflectance spectroscopy, steady-state fluorescence and time correlated single photon counting (TCSPC) measurements. Deconvolution of the diffuse reflectance spectra of eosin y on TiO2 revealed the formation of H-aggregates, with the extent of H-aggregation increasing with increasing dye-loading concentration. The resultant bathochromic shift from the monomer diffuse reflectance maximum is due to Charge-transfermediated H-aggregates The fluorescent maximum also shifts with increasing dye loading concentration starting at 537.5 nm at a dye loading concentration of 7.5x10-7 M and shifting to 585 nm at a dye loading concentration of 10-3 M. The fluorescent lifetime of eosin y in acetonitrile was measured to be 3.62 ns at 5x10-7 M. The fluorescent lifetime of EY/TiO2 was measured to be 0.38 ns and EY/ZrO2 was measured to be 1.47 ns at 5x10-7 M. The fluorescent lifetime of EY/TiO2 is significantly shorter that eosin y in both solution and on ZrO2 which is consistent with quenching from electronic injection. Furthermore, the lifetime of EY/ZrO2 was quenched from 1.47 ns to 0.39 ns at dye loading concentration of 1x10-5 M consistent with increasing H-aggregation. Showing that for eosin y aggregation is hampering electronic injection.

DOI

http://dx.doi.org/10.21220/s2-8as4-ca68

Rights

© The Author

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