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Origin of Spectral Band Patterns in the Cosmic Unidentified Infrared Emission

Héctor Álvaro Galué and Grisell Díaz Leines
Phys. Rev. Lett. 119, 171102 – Published 23 October 2017
Physics logo See Synopsis: Explaining Mysterious Cosmic Emissions
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Abstract

The cosmic unidentified infrared emission (UIE) band phenomenon is generally considered as indicative of free-flying polycyclic aromatic hydrocarbon molecules in space. However, a coherent explanation of emission spectral band patterns depending on astrophysical source is yet to be resolved under this attribution. Meanwhile astronomers have restored the alternative origin as due to amorphous carbon particles, but assigning spectral patterns to specific structural elements of particles is equally challenging. Here we report a physical principle in which inclusion of nonplanar structural defects in aromatic core molecular structures (π domains) induces spectral patterns typical of the phenomenon. We show that defects in model π domains modulate the electronic-vibration coupling that activates the delocalized π-electron contribution to aromatic vibrational modes. The modulation naturally disperses C=C stretch modes in band patterns that readily resemble the UIE bands in the elusive 69μm range. The electron-vibration interaction mechanics governing the defect-induced band patterns underscores the importance of π delocalization in the emergence of UIE bands. We discuss the global UIE band regularity of this range as compatible with an emission from the delocalized sp2 phase, as π domains, confined in disordered carbon mixed-phase aggregates.

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  • Received 29 March 2017

DOI:https://doi.org/10.1103/PhysRevLett.119.171102

© 2017 American Physical Society

Physics Subject Headings (PhySH)

Atomic, Molecular & OpticalGravitation, Cosmology & Astrophysics

Synopsis

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Explaining Mysterious Cosmic Emissions

Published 23 October 2017

A theoretical study shows how hydrocarbons with structural defects might produce unexplained peaks in the cosmic infrared spectrum.

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Authors & Affiliations

Héctor Álvaro Galué*

  • Department of Physics and Astronomy, Vrije Universiteit, de Boelelaan 1081, 1081HV Amsterdam, Netherlands

Grisell Díaz Leines

  • Interdisciplinary Centre for Advanced Materials Simulation, Ruhr-Universität Bochum 44780 Bochum, Germany

  • *h.alvarogalue@gmail.com

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Issue

Vol. 119, Iss. 17 — 27 October 2017

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