Instrumentation
Spectrofluorimeter—a Shimadzu RF-540 was used for fluo-
rescence spectra and intensity measurements. Spectrofluorime-
tere was equipped with a 150W xenon lamp. A 1.0 cm quartz
cell was used. Slit widths of both monochromator were set at
5 nm.
pH meter—aMetrohm model 654 was used for pH measure-
ments.