DENSITIES AND REFRACTIVE-INDEXES OF H2SO4 HNO3/H2O SOLUTIONS TO STRATOSPHERIC TEMPERATURES/

The Lorentz-Lorenz relation is used to estimate the refractive index o f aqueous H2SO4/HNO3 solutions (5-70 wt%) for wavelengths from the nea r-ultraviolet to the near-infrared (0.35-2 mu m) and for temperatures from 370 K to stratospheric temperatures (185 K). The molecular refrac tivities of the involved species are based on data of the binary solut ions at room temperature. For the extrapolation to low temperatures, a careful estimate of the density of the ternary solutions has been per formed. The accuracy of the model predictions is estimated to be bette r than 2%.