OPTICAL-PROPERTIES OF POLY-HCN AND THEIR ASTRONOMICAL APPLICATIONS

Matthews (1992) has proposed that HCN ''polymer'' is ubiquitous in the solar system. We apply vacuum deposition and spectroscopic techniques previously used on synthetic organic heteropolymers (tholins), keroge ns, and meteoritic organic residues to the measurement of the optical constants of poly-HCN in the wavelength range 0.05-40 mu m. These meas urements allow quantitative comparison with spectrophotometry of organ ic-rich bodies in the outer solar system. In a specific test of Matthe ws' hypothesis, poly-HCN fails to match the optical constants of the h aze of the Saturnian moon, Titan, in the visible and near-infrared, de rived from astronomical observations and standard models of the Titan atmosphere. In contrast, a tholin produced from a simulated Titan atmo sphere matches within the probable errors. Poly-HCN is much more N-ric h than Titan tholin.