Deuterium Isotope Fractionation of Polycyclic Aromatic Hydrocarbons in Meteorites as an Indicator of Interstellar/Protosolar Processing HistoryOPEN ACCESS 

· by · in , ,

Heather V. Graham, Jamie E. Elsila, Jason P. Dworkin, Scott A. Sandford and Jose C. Aponte

Life 2022, 12(9), 1368

LINK (OPEN ACCESS)
PDF (DOWNLOAD)

“The stable isotope composition of soluble and insoluble organic compounds in carbonaceous chondrites can be used to determine the provenance of organic molecules in space. Deuterium enrichment in meteoritic organics could be a residual signal of synthetic reactions occurring in the cold interstellar medium or an indicator of hydrothermal parent-body reactions. δD values have been measured in grains and bulk samples for a wide range of meteorites; however, these reservoirs are highly variable and may have experienced fractionation during thermal and/or aqueous alteration. Among the plethora of organic compounds in meteorites are polycyclic aromatic hydrocarbons (PAHs), which are stable and abundant in carbonaceous chondrites, and their δD ratio may preserve evidence about their formation environment as well as the influence of parent-body processes. This study tests hypotheses about the potential links between PAHs-deuteration concentrations and their formation conditions by examining the δD ratio of PAHs in three CM carbonaceous chondrites representing an aqueous alteration gradient. We use deuterium enrichments in soluble 2–5-ring PAHs as an indicator of either photon-driven deuteration due to unimolecular photodissociation in warm regions of space, gas-phase ion–molecule reactions in cold interstellar regions of space, or UV photolysis in ices. We also test hypothesized reaction pathways during parent-body processing that differ between partially and fully aromatized PAHs. New methodological approaches were developed to extract small, volatile PAHs without fractionation. Our results suggest that meteoritic PAHs could have formed through reactions in cold regions, with possible overprinting of deuterium enrichment during aqueous parent-body alteration, but the data could not rule out PAH alteration in icy mantles as well.”

Related posts (automatically generated):

  1. The evolution of polycyclic aromatic hydrocarbons under simulated inner asteroid conditionsOPEN ACCESS 
  2. Polycyclic aromatic hydrocarbons in carbonaceous chondrites can be used as tracers of both pre-accretion and secondary processesOPEN ACCESS 
  3. Influence of hydrothermal asteroidal conditions on the molecular structure and isotopic compositions of polycyclic aromatic hydrocarbons
  4. Link between Polycyclic Aromatic Hydrocarbon Size and Aqueous Alteration in Carbonaceous Chondrites Revealed by Laser Mass Spectrometry
  5. The amino acid and polycyclic aromatic hydrocarbon compositions of the promptly recovered CM2 Winchcombe carbonaceous chondriteOPEN ACCESS 
  6. Hydrogen and carbon isotopic ratios of polycyclic aromatic compounds in two CM2 carbonaceous chondrites and implications for prebiotic organic synthesis
  7. Identification and Discrimination of Polycyclic Aromatic Hydrocarbons Using Raman Spectroscopy
  8. The photochemical evolution of polycyclic aromatic hydrocarbons and nontronite clay on early Earth and MarsOPEN ACCESS 
  9. Polyaromatic hydrocarbons in the Mukundpura (CM2) Chondrite
  10. Phosphorus Speciation in Hydrous Carbonaceous Meteorites: Indications of the Degree of Oxidation During Hydrothermal Processing
Tags: , , , , ,