Crystalline ices-Densities and comparisons for planetary and interstellar applications

Results are presented from recent density measurements on twenty-nine crystalline ices at temperatures appli-cable to the outer Solar System and the interstellar medium. For each ice we report both a density and a refractive index at 670 nm, quantities needed to calculate infrared band strengths, comple x indices of refraction, and, ultimately, molecular abundances. Comparisons are made between densities obtained from micrometer-size crystalline ice samples prepared by vapor-phase deposition and the larger crystals (mm scale) used in diffraction work, and often made by the slow cooling of a liquid or a vapor in a sealed capilla r y tube. A strong positive correlation is found between the two sets of crystalline-ice densities.