Investigation of interstellar carbonaceous dust distribution in the direction of galactic center

There is considerable uncertainty as to the amount of carbon incorporated in interstellar dust. The aliphatic hydrocarbon component of the carbonaceous dust produces a significant 3.4 µm absorption feature. When the absorption coefficient of the aliphatic hydrocarbons incorporated in the interstellar dust is known, the column density of the aliphatic hydrocarbon component of interstellar dust can be calculated by quantitative analysis of the 3.4 µm interstellar absorption feature. In this thesis, we generated laboratory analogues of interstellar dust by experimentally mimicking interstellar/circumstellar conditions. The absorption coefficient measurements of aliphatic hydrocarbons incorporated in the analogues were carried out by combining FTIR and 13C NMR spectroscopy methods. The results allowed direct calibration of the astronomical observations and provided precise estimates of the amount of aliphatic carbon locked in the interstellar dust. In addition, we applied a new method to measure the 3.4 µm interstellar absorption over wide fields. This method is based on spectrophotometric measurements by using an infrared imaging camera equipped with narrow-band filters to sample the interstellar spectrum. We combined laboratory and observational studies to obtain maps that show the distribution of the aliphatic carbon and total carbon in the interstellar dust along the line of sight to the Galactic center. It has been found that interstellar dust grains contain significant amount of aliphatic hydrocarbons and interstellar medium carbon abundances vary in small scales by taking values above and below the cosmic abundances.