Radiation chemistry in the Jovian stratosphere: laboratory simulations

Low-pressure continuous-flow laboratory simulations of plasma induced chemistry in H2/He/CH4/NH3 atmospheres show radiation yields of hydrocarbons and nitrogen-containing organic compounds that increase with decreasing pressure in the range 2-200 mbar. Major products of these experiments that have been observed in the Jovian atmosphere are acetylene (C2H2), ethylene (C2H4), ethane (C2H6), hydrogen cyanide (HCN), propane (C3H8), and propyne (C3H4). Major products that have not yet been observed on Jupiter include acetonitrile (CH3CN), methylamine (CH3NH2), propene (C3H6), butane (C4H10), and butene (C4H8). Various other saturated and unsaturated hydrocarbons, as well as other amines and nitriles, are present in these experiments as minor products. We place upper limits of 10(6)-10(9) molecules cm-2 sec-1 on production rates of the major species from auroral chemistry in the Jovian stratosphere, and calculate stratospheric mole fraction contributions. This work shows that auroral processes may account for 10-100% of the total abundances of most observed organic species in the polar regions. Our experiments are consistent with models of Jovian polar stratospheric aerosol haze formation from polymerization of acetylene by secondary ultraviolet processing.     

Polycyclic aromatic hydrocarbons in the atmospheres of Titan and Jupiter

Polycyclic aromatic hydrocarbons (PAHs) are important components of the interstellar medium and carbonaceous chondrites, but have never been identified in the reducing atmospheres of the outer solar system. Incompletely characterized complex organic solids (tholins) produced by irradiating simulated Titan atmospheres reproduce well the observed UV/visible/IR optical constants of the Titan stratospheric haze. Titan tholin and a tholin generated in a crude simulation of the atmosphere of Jupiter are examined by two-step laser desorption/multiphoton ionization mass spectrometry. A range of two- to four-ring PAHs, some with one to four alkylation sites are identified, with net abundance approximately 10(-4) g g-1 (grams per gram) of tholins produced. Synchronous fluorescence techniques confirm this detection. Titan tholins have proportionately more one- and two-ring PAHs than do Jupiter tholins, which in turn have more four-ring and larger PAHs. The four-ringed PAH chrysene, prominent in some discussions of interstellar grains, is found in Jupiter tholins. Solid state 13C NMR spectroscopy suggests approximately equal to 25% of the total C in both tholins is tied up in aromatic and/or aliphatic alkenes. IR spectra indicate an upper limit in both tholins of approximately equal to 6% by mass in benzenes, heterocyclics, and PAHs with more than four rings. Condensed PAHs may contribute at most approximately 10% to the observed detached limb haze layers on Titan. As with interstellar PAHs, the synthesis route of planetary PAHs is likely to be via acetylene addition reactions.     

国外煤层气资源与开发概况

介绍了国外主要是美国煤层气的资源、开发状况、勘探开采方法、影响煤层生产能力的地质因素,开发成本、科研机构、会议以及利用概况。