Investigation of two-photon absorption properties in branched alkene and alkyne chromophores.
Novel alkene and alkyne branched structures have been synthesized, and their two-photon absorption (2PA) properties are reported. This series of alkene and alkyne trimer systems tests the mechanistic approach for enhancing the 2PA process which is usually dictated by the pi-bridging, delocalization length, and corresponding charge transfer on the 2PA cross sections. The results suggest that alkene branched systems have higher 2PA cross sections. While steady-state absorption and emission measurements were not successful in predicting the observed trend of 2PA cross sections, time-resolved measurements have explained the trends observed. It was found that, upon photoexcitation, there is an ultrafast charge localization to an intramolecular charge-transfer (ICT) state, followed by the presence of a solvent and conformationally relaxed ICT state in these branched systems.
Bhaskar
Ajit
A
Department of Chemistry and Macromolecular Science, University of Michigan, Ann Arbor, Michigan 48109, USA.
Ramakrishna
Guda
G
Lu
Zhikuan
Z
Twieg
Robert
R
Hales
Joel M
JM
Hagan
David J
DJ
Van Stryland
Eric
E
Goodson
Theodore
T