Phosphorescence band blue shift

At 77 K the position of the 0-0 band is generally blue shifted for exposed tryptophans and red shifted for buried tryptophans. Along with a shift in wavelength to the red, the phosphorescence lifetime decreases.(28) The single tryptophan of human serum albumin shows red-shifted phosphorescence and D - L triplet zero-field splitting, indicating that it is in a hydrophobic environment. 29 ... 

Fluorescence and Phosphorescence. Essentially the same effects that influence absorption of radiation are found to perturb the emission processes. Fluorescence spectra are red- or blue-shifted along with the corresponding band of the absorption spectrum. 

It was mentioned earlier that the linewidth of the ODMR signal increases as the phosphorescence is monitored towards the edges of the 0—0 emission band. If the emission is monitored at the center of the 0—0 band with narrow monochromator slits, a trend in the linewidth of the ODMR signals is also observed between samples. It appears that an increase in the ODMR linewidth is correlated with a blue shift in the phosphorescence origin as shown in Fig. 16 1 3). This increase in line-width may be connected with increasing exposure of the tryptophan site to the solvent medium. The 2 ODMR transition is always observed... 

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