Date of Award

Spring 2009

Document Type

Restricted Thesis

Terms of Use

© 2009 Robert Mohr. 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

Catherine Hirshfeld Crouch


We report measurements of the excitation energy dependence of the fluorescence intermittency of single CdSe/ZnS core/shell nanocrystals (NCs) using two different excitation energies. The lower excitation wavelength, 532 nm, corresponds to excitation 270 me V above the band gap. The higher energy, 405 nm, corresponds to excitation 1000 me V above the band gap. At each excitation energy, 77 individual NCs were measured for 1500 s. The off-time probability density distribution from each individual NC follows a power law with a distribution of slopes that is insensitive to the difference in excitation energy studied. The on-time probability density distributions for individual and aggregated data follow a truncated power law with slope distributions that are also insensitive to the difference in excitation energy. However, the distribution of truncation times obtained from the individual NCs at 405 nm excitation is peaked at a shorter value than the distribution obtained with 532 nm excitation. These results suggest that blinking dynamics change for excitation far above the 1P3/21Pe state.