Simulation experiments, solar

However, we need information on the atmospheric composition in order to plan and carry out simulation experiments. Although the four terrestrial planets originated from the same solar matter, their atmospheres are completely different. This is due to ... 

The volatile-trapping mechanism has a further problem associated with the temperature. Very volatile molecules such as N2, CO and CH4 are not easily trapped in laboratory ice simulation experiments unless the ice temperature is 75 K, which is somewhat lower than the estimated Saturnian subnebula temperature. This has led to the suggestion that the primary source of nitrogen within the Titan surface ices was NH3, which became rapidly photolysed to produce H2 and N2 upon release from the ice. The surface gravity is insufficient to trap the H2 formed and this would be lost to space. However, the origin of methane on Titan is an interesting question. Methane is a minor component of comets, with a CH4/CO ratio of clCT1 compared with the present atmospheric ratio of > 102. The D/H ratio is also intermediate between that of comets and the solar nebula, so there must be an alternative source of methane that maintains the carbon isotope ratio and the D/H isotope ratio and explains the abundance on Titan. 

The kinetics of the various reactions have been explored in detail using large-volume chambers that can be used to simulate reactions in the troposphere. They have frequently used hydroxyl radicals formed by photolysis of methyl (or ethyl) nitrite, with the addition of NO to inhibit photolysis of NO2. This would result in the formation of 0( P) atoms, and subsequent reaction with Oj would produce ozone, and hence NO3 radicals from NOj. Nitrate radicals are produced by the thermal decomposition of NjOj, and in experiments with O3, a scavenger for hydroxyl radicals is added. Details of the different experimental procedures for the measurement of absolute and relative rates have been summarized, and attention drawn to the often considerable spread of values for experiments carried out at room temperature (-298 K) (Atkinson 1986). It should be emphasized that in the real troposphere, both the rates—and possibly the products—of transformation will be determined by seasonal differences both in temperature and the intensity of solar radiation. These are determined both by latitude and altitude. 

Ultraviolet) instrument and from SAGE II (Stratospheric Aerosol and Gas Experiment II), together with supporting data from ozonesondes and satellite instruments such as SME (Solar Mesosphere Explorer) and TOMS (Total Ozone Mapping Spectrometer). The model interpolates monthly ozone values to its timestep and this time-varying ozone repeats every simulation year. The model currently does not allow the ozone to become interactive, neither does it represent any change in ozone due to chemical processes, although work is underway to incorporate these features. 

In this paper our results to simulate the photoactive semiconductor/ electrolyte interface in UHV by adsorbing halogens and H20 on semiconductor surfaces are described. For these experiments layer type compounds and ternary chalcogenides have been considered because clean faces can easily be prepared by cleaving the crystals in UHV and because the reactions with halogens are intensively studied for photoelectrochemical solar cells. 

A Pyrex glass bottle of 50-mL capacity was used as batch reactor. In these flasks 40 mL of water was the total volume. Solar irradiation was simulated by a Hanau Suntest (AMI) lamp. Total radiation measurements were carried out with an YSI corporation power meter. Experiments were performed at room temperature (25°C) reaching up to 32°C during irradiation. 

R.D. Hurtubise, J.E. Havel, E.E. Little (1998). The effects of ultraviolet-B radiation on freshwater invertebrates Experiments with a solar simulator. Limnol Oceanogr., 43, 1082-1088. 

In virtually all experiments that simulate the synthesis of a primordial soup, enantiomers of amino acids and sugars do not occur instead only racemates have been produced (Miller 1953). It is difficult to imagine how only one of the enantiomers formed under the conditions of a primordial broth. Instead, import and identification of biologically relevant molecules in meteorites and comets appears as a more straightforward path. The compounds found in a meteorite provide a natural record of prebiotic chemistry in the early solar system and is closest to the onset of life. 

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