Testing Densities and Refractive Indices of Extraterrestrial Ice Components Using Molecular Structures - Organic...

Area of Science:

• Astrochemistry
• Solid-state physics
• Spectroscopy

Background:

• Infrared spectra are vital for determining molecular abundances and chemistry in icy astronomical objects.
• Laboratory measurements of reference spectra, refractive index (n), and density (ρ) for candidate ices are essential for astrochemical studies.

Purpose of the Study:

• To present new measurements of refractive index (n) and density (ρ) for over thirty C-, H-, and O-containing compounds in ice form.
• To analyze these measurements by comparing data within chemical families and with liquid-phase data.
• To explore the computation and structural relevance of molar refraction (RM) for ices.

Main Methods:

• Laboratory measurement of refractive index (n) and density (ρ) for over thirty acyclic and cyclic compounds forming ices.
• Comparative analysis of ice data within homologous series and isomeric pairs.
• Comparison of ice properties with corresponding room-temperature liquid properties.
• Calculation of molar refraction (RM) from measured n and ρ values.

Main Results:

• New n and ρ data were obtained for over thirty compounds in ice form, covering seven chemical families.
• Structure-based comparisons revealed trends and potential anomalies in ice properties.
• Ice properties were compared to liquid-phase data, highlighting differences relevant to astrochemical applications.
• Molar refraction (RM) values were computed and compared with predictions based on molecular structures.

Conclusions:

• The presented n and ρ data provide valuable references for astrochemical modeling of icy bodies.
• Structure-property relationships in ices were elucidated through comparative analysis.
• The study offers insights into using calculated RM and measured n to estimate ice densities when direct measurements are unavailable.