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Project Progress

We installed a new FTIR spectrometer to our experimental apparatus (Fig. 1). The new spectrometer is in perfect condition, allowing us to take spectra of ices at near-IR and middle-IR regions, which are comparable to astronomy observations. We also designed some new parts to improve the experimental apparatus. For example, a new OFHC copper coldhead shield (Fig. 2) was made and installed into the machine. That reduces the mass spectral background significantly. Recently, we are assembling a proton source to simulate the effects of solar wind on low temperature ices.

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We studied 5keV electron irradiation of D₂O ice at 12K (Fig. 3). The experimental results indicate that the production rates of D₂, O₂ and D₂O₂ in amorphous ice are higher than those in crystalline ice. That might help us to understand the chemical processes in cold molecular cloud dust grains and Oort cloud objects. We also conducted experiments to study the amorphization of cubic crystalline water ice, which is important for understanding the history of Kuiper Belt Objects.

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In the experiments of water-free ices, we investigated the formation of ozone in interstellar and cometary ice analogs by electron irradiation of solid oxygen. Pure methane ices (CH₄) were irradiated at 10 K with energetic electrons to mimic the energy transfer processes that occur in the track of the trajectories of MeV cosmic ray particles (Fig. 4). Electron irradiation of carbon monoxide ice shows that a series of new carbon-chain (C₃, C₆) and carbon oxide species were produced including the linear isomers of C₂O, C₃O, C₄O, C₅O, C_6/7O, CO₂, C₃O₂, C₄O₂, and C₅O₂ (Fig. 5). Those species might be able to form organic molecules when hydrogen is available. We detected the formation of C_s symmetric nitroformyl radical, OCNO(X ²A”), in the study of N₂/CO₂ ice mixtures (Fig. 6).

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The experimental work has already been extended to the ice mixtures of water and other molecules, such as O₂, N₂, C₂H₄, CO₂, CO, etc. Most of the experiments are finished. We hope those ice mixtures can give us some information about formation of organic molecules in water-rich environments in space.