PHOTOPHYSICS OF LASER-DYES BOUND TO POLY(METHACRYLIC ACID) IN WATER

The fluorescence emission characteristics have been recorded for a series of coumarin and rhodamine dyes in a water medium that includes the polyelectrolyte, poly(methacrylic acid) (PMAA). Observations include a high level of solubility for the coumarin dyes in aqueous polymer solution (pH 3.0) and the elimination of dye aggregation for the rhodamines. The emission parameters of quantum yield, lifetime, and polarization were all shown to be increased on incorporation of dye in dilute polymer solution. Analysis of the Stokes-shift of emission and fluorescence yields revealed that the binding of dye to PMAA at the appropriate pH (3.0) in which the polyelectrolyte is uncharged and ''hypercoiled'' provides a viscous, and relatively ''dry'' microdomain that favors efficient emission and protection from quenchers.