D to H ratio and the origin and evolution of Titan's atmosphere

摘要: A value of 1.7 × 10^(−3) has been reported for the ratio CH_3D to CH_4 in stratosphere saturnian moon Titan. lower 6 10^(−4) this deeper part Titan's atmosphere was by de Bergh et al. For comparison we note that on Saturn and Jupiter is 8.7 10^(−5) 6.7 10^(−5), respectively (see Table 1). We estimate uncertainties all these observations data reduction be about a factor 2. Despite it appears enriched deuterium ≥3 relative Saturn. Potential causative factors examined here enrichment are condensation form tropospheric methane clouds, fractionation occurring over hypothetical CH_4–C_2H_6 ocean between clathrate crust beneath, which occurred during formation Titan as result evolution atmosphere. conclude greater observed probably derived from subsequent driven photochemistry.