Optical Characterization of Interstellar Ice Analogues

Since its first identification, water ice has been observed in the insterstellar medium (ISM) along several lines of sight and in different sources, mainly in dense molecular clouds. Water is the most abundant component of ice observed in space. However, other molecular  species have been identified as minor ice components by their spectroscopic features in the infrared (IR) region. There are still many open questions about the role of the ice mantles in phenomena, such as low-temperature dust coagulation, or non-thermal desorption mechanisms. To tackle such questions, it is important to identify the physical state and molecular composition of ices, and this relies on preliminary laboratory characterization.

An experiment is being developed with the goal in mind to characterize the optical properties of astrophysically-relevant solids (ice mixtures, silicates, and carbonaceous materials). For this experiment, we will use a cryostat coupled to both a Fourier Transform Infrared (FTIR) spectrometer and a Terahertz Time-Domain Spectrometer (TDS), to characterize samples in two different spectral regions. This combination of spectral studies will provide information regarding their chemical, physical, and optical properties. When analyzed together with astronomical observations and theoretical models, we will better understand the roles of solid materials for several different environments.

Computer-generated diagram of the FTIR/THz TDS rack system. The THz TDS instrument (blue) is shown mounted next to the FTIR spectrometer (tan), above which is situated a rack system capable of easily transferring a closed-cycle cryostat (orange). This rack system allows for the ease of measuring an ice sample at multiple wavelengths in near-realtime.
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