Photoexcited carrier relaxation and localization in Bi2Sr2Ca1-yYyCu2O8 and YBa2Cu3O7-delta: A study by femtosecond time-resolved spectroscopy - Thomas, T; Stevens, C; Choudhary, A; Ryan, J; Mihailovic, D; Mertelj, T; Forro, L; Wagner, G; Evetts, J (1996)