[A study of nonlinear fraction frequency fluorescence spectra for tryptophane]

There are two fluorescence peaks at 350 and 700 nm for tryptophane in pH 7.43 Tris buffer solution, as the excited wavelength is at 296 nm. The fluorescence peak at 700 nm is a nonlinear 1/2 fraction frequency fluorescence peak for tryptophane. The fluorescence intensities of 350 and 700 nm peaks are proportional to tryptophane concentration in the range of 0-1 x 10(-5) mol.L-1. The half width of (delta lambda)350 for 350 nm and (delta lambda)700 for 700 nm peak decreases slowly with tryptophane concentration. And the F700 nm/F350 nm and (delta lambda)700/(delta lambda)350 are constant. The two peaks have similar fluorescence behavior. An energy level principle for fraction frequency fluorescence and resonance principle of fraction frequency have been proposed, and applied to explaining the fraction frequency fluorescence of tryptopane.