Enhanced Two-Photon Absorption in Dendrimers T. Goodson III, University of Michigan, DMR-0134691

1. Enhanced Two-Photon Absorption in Dendrimers T. Goodson III, University of Michigan,DMR-0134691 • Enhanced Two-Photon Absorption (..)is possible with branched organic macromolecules. • With these particular dendrimers based on a triphenylamine-core the enhancement in (..) is very large! • Time-resolved fluorescence anisotropy measurements suggest that the generation dependent enhancement of (...) may be connected with the decreasing residual anisotropy value. • These measurements further suggest that the fundamental excitation unit in the dendrimers extends beyond the situation for the trimer. • This is useful for designing new macromolecules for superior two-photon properties where a large number of chromophores participate in the excitation.

2. Enhanced Two-Photon Absorption in Dendrimers T. Goodson III, University of Michigan,DMR-0134691 Educational Aspects of Study: Graduate Student Ajit Bhaskar (Macromoelcular Engineering) and Postdoctoral Fellow Ying Wang have worked on this project in the PI’s lab. The dedrimer systems were synthesized by Professor Mireille Blanchard-Desce’s group at the Université de Rennes. The project incorporated a number of spectroscopic tools that these two scientists from the PI’s group have used thoroughly. While more sophisticated measurements were utilized such as time-resolved absorption and emission as well as 3-pulse photon echo measurements, other methods that were more familiar to the summer students that worked with the two scientists in our group. This included linear absorption and emission measurements. This allowed for the students (undergraduate (REU) and high school) to first contribute to this project with techniques that they were already familiar with and gave them the time to understand the more sophisticated and less familiar techniques. This has been a rewarding experience for students and scientists at many levels! Outreach Activities: With support from the NSF-REU program and from project SEED (ACS) two summer students have participated on this project this summer. One undergraduate (Unique Luna) who joined the group in the fall is working with graduate student Ajit Bhaskar on two-photon emission measurements. The second student (Latisha Burrell) is a high school student from the Detroit Public Schools as is part of the ACS-SEED program headed by the Detroit section of the ACS. She is working with Dr. Ying Wang in the PI’s group on the photo-physical properties of dendrimers and the possibility of enhanced two-photon absorption and emission. Ying Wang (left) and Ajit Bhaskar (right) stand before the Two-photon emission (TPE) apparatus used in studies of the mechanism in dendrimers.