DURIP97 Instrumentation for Characterization of Two-Photon Absorbing Organic Materials

摘要

DURIP funds were used to purchase a Spex Model FL112 High Performance Research Grade Fluorimeter and a Nd:YAG-pumped nanosecond Optical Parametric Oscillator Laser System with tunability from 440 nm - 1800 nm. This equipment was used to measure the two-photon absorption spectra for a variety of molecules from different classes and identify promising candidate molecules to meet DoD requirements for a variety of applications. A strategy for the design of molecules with large two-photon absorption cross sections has been developed. The strategy is based on the concept that symmetric charge transfer, from the ends of a conjugated system to the middle, or vice versa, upon excitation is correlated to enhanced two-photon absorption cross sections. It was shown that newly synthesized bis-styrylbenzene derivatives with donor-acceptor-donor, and acceptor-donor-acceptor structural motifs exhibit exceptionally large two-photon absorption cross sections, up to roughly 400 times that of trans-stilbene.