Optische Aufheller als Laserfarbstoffe

Abstract

The singlet absorption, triplet absorption and the absolute fluorescence spectra together with the fluorescence quantum yields and fluorescence decay times as well as the laser performance (tuning range, conversion efficiency, photochemical stability) of nine fluorescent brightening agents have been measured in ethanol at room temperature. High fluorescence quantum yields of over 0.75 with short fluorescence decay times of well under one nanosecond have been obtained. With the exception of two fluorescent brightening agents the tuning ranges are in the violet‐blue region between 415 and 447 nm. The conversion efficiencies range from 1 to 15%. The photochemical stability of the optical brighteners in solution with energy half‐life values between 2 × 104 and 105 J/l, corresponding to average lifetimes of 75 to 200 photons per molecule, is poor in comparison to their known photochemical stability in the adsorbed state.