ONE-COLOR AND 2-COLOR SEQUENTIAL 2-PHOTON EXCITATION OF VISIBLE NI-2+ LUMINESCENCE IN NI-2+-CSCDCL3

Excitation of visible 3A2g←1T2g (Oh notation) emission centered at {reversed tilde} 610 nm has been achieved in Ni2+-doped CsCdCl3 by exciting with a krypton laser (647.1 nm) below the 3A2g→1T2g absorption, where no absorption band can be seen. The time dependence of the build-up of visible emission to steady state after the start of the excitation pulse indicates involvement of the metastable, first excited state of Ni2+, 3T2g. Through a series of one- and two-color excitation measurements, it is demonstrated that this is essentially a single-ion process involving the sequential absorption of two photons; the first in an extremely weak absorption from the groundstate (3A2g) to a very high vibrational level of 3T1g(3F) and/or 1Eg, and the second from the first excited state, 3T2g, to 3T1g(3P). © 1990.