Origin of Spectral Band Patterns in the Cosmic Unidentified Infrared Emission

Héctor Álvaro Galué, Grisell Díaz Leines

Research output: Contribution to JournalArticleAcademicpeer-review

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 6-9 μm 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.

Original languageEnglish
Article number171102
Pages (from-to)1-6
Number of pages6
JournalPhysical Review Letters
Volume119
Issue number17
DOIs
Publication statusPublished - 23 Oct 2017

Fingerprint

Dive into the research topics of 'Origin of Spectral Band Patterns in the Cosmic Unidentified Infrared Emission'. Together they form a unique fingerprint.

Cite this