(18) Fluorescence data were obtained on a Spex Fluorolog I1 fluorimeter with a 450-W Xe arc lamp, 7.2-nm excitation, and 1.8-nm emission band widths and photon counting detection as follows: blue form, exc 360 nm (Melles Griot 360-nm interference filter), em 460 nm (Spex KV 400 filter); red form, exc 530 (Corion 550-nm interference cut-on filter), em 590 nm (Spex KV 550 filter). Spectra of the two forms varied in intensity, but not shape, with ...
