LAUSR

Abstract With the change of pH, the metastable zone of PLP in water was measured at various temperatures by applying laser monitoring method under normal pressure. The metastable zone became wider as the pH increased within the studied scope, but it became narrower as the temperature increased within the studied scope. With the change of supersaturation ratio, the induction period of PLP in water was also measured at various temperatures. According to the classical homogeneous nucleation theory, the crystal-solution interfacial tensions at various temperatures were calculated which were then used to calculated the primary nucleation parameters containing per unit volume free energy change (ΔGv), critical free energy change for the formation of critical crystal nucleus (ΔG*), radius of critical crystal nucleus (r*) and the molecular number in the critical crystal nucleus.