Morphological study into the temperature dependence of solid ammonia under astrochemical conditions using vacuum ultraviolet and Fourier-transform infrared spectroscopy

Publication

Reference: Dawes Anita, Mukerji Robin J., Davis Michael P., Holtom Philip D., Webb Sarah M., Sivaraman Bhalamurugan, Hoffmann Søren V., Shaw David A., Mason Nigel J. (2007). Morphological study into the temperature dependence of solid ammonia under astrochemical conditions using vacuum ultraviolet and Fourier-transform infrared spectroscopy. J. Chem. Phys., 126, 244711.

Names

Title: Morphological study into the temperature dependence of solid ammonia under astrochemical conditions using vacuum ultraviolet and Fourier-transform infrared spectroscopy
Abstract: The authors present the results of a morphological study of solid ammonia using both Fourier-transform infrared and vacuum ultraviolet (VUV) spectroscopy. Dramatic changes in the VUV and infrared spectra at temperatures between 65 and 85K provide a deeper insight into the structure of ammonia ice particularly with the observation of an exciton transition at 194nm (6.39eV) in the VUV spectrum, revealing a structure that is composed of crystallites. A complementary structure is observed in the IR spectrum at 1100cm$^-1$ which is assigned to the symmetric deformation of ammonia molecules at the surfaces of the crystallites. Such spectral signatures may be used to identify the environment within which the ammonia ice is formed and provide a new route for obtaining information on the physical and chemical conditions occurring within the interstellar medium, on the surfaces of planetary bodies, and in Kuiper belt objects.
Keywords: spectroscopy, transmission, absorbance spectra, band position, band vibration mode, VUV, mid-IR, amorphous, low temperature, crystalline, phase change, molecular solid, ice, NH3
Content: spectral data, band list data, sample

Doi

10.1063/1.2743426

Identifiers