“…By varying the excitation wavelength, nonlinear spectroscopy, including two-photon absorption and two-photon fluorescence, of a wide range of samples can be studied in detail to understand the molecular interactions under intense incident light. As an example, a series of studies on the two-photon absorption properties and subsequent two-photon fluorescence of a series of cyanoacetic acid triphenylamine derivatives in toluene were recently reported . Here, the electron donor groups employed are the triphenylamine moiety, cyanoacetic acid moiety as electron acceptor groups, and vinylene or phenylethyne as the π-bridge.…”