title: Measuring Enthalpy of Sublimation of Volatiles by Means of Piezoelectric Crystal Microbalances.
abstract: Piezoelectric Crystal Microbalances (PCM's) are widely used to study the chemical processes involving volatile compounds in any environment, such as condensation process. Since PCM's are miniaturized sensor, they are very suitable for planetary in situ missions, where can be used to detect and to measure the mass amount of astrobiologically significant compounds, such as water and organics. This work focuses on the realization and testing of a new experimental setup, able to characterize volatiles which can be found in a planetary environment. In particular the enthalpy of sublimation of some dicarboxylic acids has been measured. The importance of dicarboxylic acids in planetology and astrobiology is due to the fact that they have been detected in carbonaceous chondritic material (e.g. Murchinson), among the most pristine material present in our Solar System. In this work, a sample of acid was heated in an effusion cell up to its sublimation. For a set of temperatures (from 30 °C to 75 °C), the deposition rate on the PCM surface has been measured. From these measurements, it has been possible to infer the enthalpy of sublimation of Adipic acid, i.e. ΔH = 141.6 ± 0.8 kJ/mol and Succinic acid, i.e. ΔH = 113.3 ± 1.3 kJ/mol. This technique has so demonstrated to be a good choice to recognise a single compound or a mixture (with an analysis upstream) even if some improvements concerning the thermal stabilization of the system will be implemented in order to enhance the results' accuracy. The experiment has been performed in support of the VISTA (Volatile In Situ Thermogravimetry Analyzer) project, which is included in the scientific payload of the ESA MarcoPolo-R mission study.
authors.affiliation: IAPS-INAF, Via del Fosso del Cavaliere 100, 00133, Rome, Italy. fabrizio.dirri@iaps.inaf.it.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Dirri
authors.affiliation: IAPS-INAF, Via del Fosso del Cavaliere 100, 00133, Rome, Italy.
authors.forename: Ernesto
authors.initials: E
authors.lastname: Palomba
authors.affiliation: IAPS-INAF, Via del Fosso del Cavaliere 100, 00133, Rome, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Longobardo
authors.affiliation: IIA-CNR, Research Area of Rome 1, Via Salaria km 29.300, 00015, Monterotondo, Rome, Italy.
authors.forename: Emiliano
authors.initials: E
authors.lastname: Zampetti
mesh_terms: D000272:Adipates / Q000737:chemistry*; D018559:Exobiology; D019802:Succinic Acid / Q000737:chemistry*; D013816:Thermodynamics; D013818:Thermogravimetry; D014835:Volatilization
chemical_list: D000272:Adipates; C029900:adipic acid; D019802:Succinic Acid
keywords: Dicarboxylic acid; Enthalpy of sublimation; Piezoelectric crystal microbalances; Planetary in-situ mission