Physical, chemical and optical properties of aqueous L-arginine phosphate (LAP) solution

The mathematical modelling of the solution growth of high quality single crystals requires a good understanding of the fluid properties. In addition to the physical and mechanical properties a detailed knowledge of the optical parameters is required to study the dynamics of the crystal growth process. Measurements of polarizability, refractive index, optical dispersion, solubility, pH, viscosity, and density were performed on aqueous L-Arginine phosphate (LAP) solutions. The index of refraction was measured with an Abbe refractometer at four different wavelengths. Optical dispersion was calculated using the Cauchy's equation. Effects of the density and kinematic viscosity of the LAP solution are discussed in terms of the dimensionless Grashof and Reynolds number allowing a better understanding of the benefits of operating under the ‘micro-g’ conditions of space for the solution growth of single crystals. The Cauchy's formula and Sellmeier formula of the refractive index have been used to determine both the gradients dn/dc and dn/dT as a function of wavelength and the polarizability of the LAP solution. The polarizability of the LAP crystal, α2, was found to be 14.50 cm3/mol and this value was in good agreement with experimental data obtained and analyzed using the well-known Lorentz-Lorenz formula.