Simultaneous Observation of Green Multiphoton Upconversion and Red and Blue NLO Processes from Polymeric Terbium(m) Complexes

摘要

Photoexcitation at a certain wavelength in the near-infrared (NIR) region followed by luminescence at a shorter wavelength in the visible domain is called near-infrared-to-visible photon upconversion.This is a rather unusual process as low-energy photons are "converted" into higher energy photons:two or three photons of NIR light are required to generate one photon of visible light.11' Nonlinear optics (NLO) is another mechanism that can lead to the generation of light at a frequency that is either twice or integral-multiples of the incident light.'2' The phenomena of two- or three-photon upconversion,and second or third harmonic generation (SHG or THG) on organic materials have received considerable attention since fluorescence detection became popular in applications such as photodynamic therapy,optical data storage,and microfabrication.