Simultaneous emission induced by one- and two-photon absorption from the charge-transfer band from aqueous solutions of europium perchlorate pumped by a repetitively pulsed nitrogen laser have been detected. These processes were verified both through the measured fluorescence intensity as a function of the laser flux and from a qualitative analysis of the two overlapping characteristic broad emission spectra, which are dependent on the excitation wavelength. A theoretical fit could be made to the laser-power-dependence data, which gave a two-photon absorption coefficient of approximately 4 × 10-49 cm4 sec/photon-molecule for this system.
© 1978 Optical Society of America
J. F. Giuliani, "Multiphoton excitation and emission from europium ions in aqueous solution," Opt. Lett. 3, 149-151 (1978)