Emission spectra of the GGR-Tb(III)complex and controls. (A) Emission spectra of GGR alone (spectrum 1 ) and Tb(III) alone (spectrum 2, coinciding with the x axis but offset for clarity). (B) Emission spectrum of the GGR-Tb(III) complex. All spectra were at 25 ºC, the excitation wavelength was 292 nm, the emission wavelength was scanned, and the bandwidths on both channels were 10 nm. [GGR] = 2.5 μM; [TbCl3,] = 25 μM. Buffer = 100 mM KCl and 10 mM PIPES, pH 6.0.