Stability of Coronene at High Temperature and Pressure

Abstract

The infrared response of coronene (C(24)H(12)) under pressure and temperature conditions up to 10 GPa and 300 °C is examined in situ using a diamond anvil cell and synchrotron-source Fourier transform infrared (FTIR) spectroscopy. Coronene is a polycyclic aromatic hydrocarbon that is present in the interstellar medium and meteorites which may have contributed to the Earth's primordial carbon budget. It appears to undergo a reversible phase transition between 2 and 3.2 GPa at ambient temperature; new intramolecular bonds in the region 840-880 cm(-1) result from compression. We document the shift of spectral features to higher wavenumbers with increasing pressure but find this change suppressed by increased temperature. By investigating the stability of coronene over a range of naturally occurring conditions found in a range of environments, we assess the survival of the molecule through various terrestrial and extraterrestrial processes. Coronene has previously been shown to survive atmospheric entry during Earth accretion; this can now be extended to include survival through geological processes such as subduction and silicate melting of the rock cycle, opening the possibility of extraterrestrial coronene predating terrestrial accretion existing on Earth.

Metallofullerene and fullerene formation from condensing carbon gas under conditions of stellar outflows and implication to stardust

“…We find that interaction of C 60 or C 70 with smaller PAHs (anthracene, naphthalene) do not exhibit remarkable reaction product spectra, because only extremely low-abundance fullerene-PAH products are observed. Small PAHs may be much less stable than coronene under the present energetic conditions (41,42).…”

PRESSURE EFFECTS IN POLYCYCLIC AROMATIC NITROGENATED HETEROCYCLES (PANHs): DIAGNOSTIC QUALITIES AND COSMOBAROMETRY POTENTIAL

“…A description of the apparatus and techniques used can be found elsewhere (Jennings et al 2010;Montgomery et al 2014) and only the salient features are summarized here. A stainless steel gasket with a 200 μm diameter sample chamber and a pre-indented thickness of 30 μm depth was placed in the diamond anvil cell.…”

“…FTIR spectra were collected using synchrotron light from the Swiss Light Source at intervals of approximately 1 GPa from 0.5 to 9.2 GPa. The change in the R1 pressure-dependent florescence line of ruby (Mao et al 1986;Jennings et al 2010) was used to directly measure pressure. Analysis of spectra was performed by removing background and, subsequently, using Fityk to fit peaks to a standard Gaussian (Wojdyr 2010).…”

“…Spectra were collected every 25-50 K. Pressure was continuously monitored during heating and adjusted to account for mechanical expansion of the DAC with heating. Further details on the error in pressure and temperature measurements are provided in a previous work (Jennings et al 2010). References.…”

Thermal expansion of coronene C24H12 at 185–416 K

“…The pressure-induced transitions in coronene from monoclinic to orthorhombic structure were suggested at 1 GPa [22], whereas Fourier transform infrared spectroscopy experiments revealed a phase transition between 2.0 and 3.2 GPa [23]. In a recent work, Zhao et al [24] argued for a transition from P2 1 /a to P2/m at 1.5 GPa and to Pmmm at 12.2 GPa.…”