JOURNAL OF PHYSICS-CONDENSED MATTER, cilt.13, sa.1, ss.195-202, 2001 (SCI-Expanded)
Absorption and luminescence measurements on Tm3+ and Ho3+ ions in LiYF4:Tm3+, LiYF4:Ho3+, and LiYF4:Tm3+, Ho3+ crystals were carried out. The data collected were used to determine the Ho3+ absorption coefficient integral for I-5(8) --> I-5(7) transition, and the integral for the overlap between the normalized Tm3+ luminescence spectrum due to the F-3(4) --> H-3(6) transition and the Ho3+ absorption band due to I-5(8) --> I-5(7) transition. The relevant critical transfer distance (R-0) that gives a measure of the Tm3+-Ho3+ coupling was determined by considering a Forster-type interaction between the ions. It was found to be 22.5 Angstrom at 300 K with the overlap integral 6.8 x 10(-19) cm(5), which is 4.41 times higher at 77 K.