The following document lists the file abstract/MUIZON_DIFISM.abs
from catalogue VI/111.
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Astronomical observational studies are proposed to determine the composition, abundance, distribution, and evolution of organic molecules (namely aliphatic hydrocarbons and nitriles) on dust grains in the interstellar medium. The ultimate goal is to understand the processes involved in the formation of these prebiogenic compounds, their chemical evolution, and the relationship between the compounds in the diffuse and dense interstellar clouds. A significant step toward this goal can be achieved by measuring the infrared spectrum in the 4500-500 cm-1 (2.0-20.0 um) region in astronomical objects which span the evolutionary range from diffuse clouds through quiescent dense molecular clouds. This proposal will only focus a subset of these observations, which will complement ongoing ground-based and airborne (Kuiper Airborne Observatory) studies. The objective for this proposal is to study the diffuse ISM dust with ISO observations over two wavelength regions that either cannot be studied from the ground at all (4.05 - 4.5 um) or sufficiently well (3.2- 3.4 um). The observations proposed target three spectral regions that are essential to understanding the distrbution of carbon among nitriles and hydrocarbons. The three carbonbearing compounds of interest are nitriles (4.35 - 4.45 um), polycyclic aromatic hydrocarbons in absorption (3.3 um), and the related C-D stretch (4.1 - 4.3 um). Ground based studies of the aliphatic hydrocarbon (3.4 um) and isonitrile (4.62um) absorption features in diffuse and dense clouds,respectively, are currently underway.The portions of the spectrum that we cannot look at from the ground may hold important keys to the overall distribution of carbon among these several types of organic materials.