Asphaltenes as model compounds of the UIBs/AIBs detected in various astrophysical objects. Part 3: Petroleum asphaltenes high energy radiation processed

Abstract

The asphaltenes isolated from a heavy petroleum fractions were subjected to radiation damage using either neutron bombardment (corpuscular radiation simulating cosmic rays) or γ-rays (high energy electromagnetic radiation). The purpose was to study how the radiation damage changes the spectral, thermal properties and other properties of the asphaltenes in a possible simulation of the destiny of these molecules exposed to the harsh circumstellar and interstellar medium. In fact, the asphaltenes were proposed as model molecules matching the MAONs model (mixed aromatic/aliphatic organic nanoparticles), the supposed carriers of the unidentified infrared bands known also as aromatic infrared bands or the unidentified infrared bands which represent a series of discrete infrared emission bands detected in numerous and different astrophysical environments. Thus, the pristine and radiation-damaged asphaltenes were studied with scanning electron microscopy, FTIR spectroscopy, electronic absorption spectroscopy, thermogravimetric analysis (TGA-DTG) and electron spin resonance.

Keywords:

• Asphaltenes
• neutron bombardment
• γ-radiolysis
• SEM
• FTIR
• UV–VIS
• TGA
• ESR
• Astrochemistry
• UIBs/AIBs/UIE

Acknowledgment

We acknowledge support from the ACIISI, Gobierno de Canarias and the European Regional Development Fund (ERDF) under grant with reference PROID2020010051. Many thanks to Dr. Michele Prata for the neutron irradiation of the asphaltene samples at the Pavia nuclear reactor. Special thanks also to Dr. Tania Ruspandini and Mr. Marco Albano from the Department of Geology and Geochemistry of the University of Rome for the key help to perform the SEM analysis.