201. The Titan Haze Simulation (THS) experiment on COSmIC. Part II. Ex-situ analysis of aerosols produced at low temperature.
- Author
-
Sciamma-O'Brien, Ella, Upton, Kathleen T., and Salama, Farid
- Subjects
- *
ATMOSPHERIC aerosols , *HAZE , *PLASMA gases , *SIMULATION methods & models ,TITANIAN atmosphere - Abstract
This paper presents the first results of the solid phase analysis of the Titan tholins generated in the Titan Haze Simulation (THS) experiments. This study complements the gas phase analysis study that was presented in a previous publication introducing the THS capabilities. In the THS experiment, the chemistry is simulated by plasma in the stream of a supersonic jet expansion. With this unique design, the gas is jet-cooled to Titan-like temperature (∼150 K) before inducing the chemistry by plasma, and remains at low temperature in the plasma discharge (∼200 K). Here, we present and discuss the results of scanning electron microscopy and infrared spectroscopy studies of THS solid aerosols produced in the four gas mixtures already studied by mass spectrometry in the gas phase: N 2 CH 4 , N 2 CH 4 C 2 H 2 , N 2 CH 4 C 6 H 6 and N 2 CH 4 C 2 H 2 C 6 H 6 . Differences in the morphology of the grains and aggregates produced in the volume of the gas phase in the plasma cavity, depending on the initial precursors, have been observed by scanning electron microscopy, that appear to be linked to differences in the growth processes and might have an impact on microphysical models. The mid-infrared spectroscopic analysis highlights changes in the nitrogen chemistry, and the abundance of aromatic compounds, depending on the initial gas mixture. A preliminary study of the aging and degradation of the THS samples with time and exposure to air and light has shown the importance, for future studies of laboratory-generated planetary aerosol analogs, of collecting, storing and characterizing samples under controlled environment. A comparison to VIMS data shows that the THS tholins produced in simpler mixtures, i.e., with a higher level of nitrogen incorporation, are more representative of Titan's aerosols. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF