Variations in the Peak Position of the 6.2 μm Interstellar Emission Feature: A Tracer of N in the Interstellar Polycyclic Aromatic Hydrocarbon Population

@article{Hudgins2005VariationsIT,
  title={Variations in the Peak Position of the 6.2 $\mu$m Interstellar Emission Feature: A Tracer of N in the Interstellar Polycyclic Aromatic Hydrocarbon Population},
  author={Douglas M. Hudgins and Charles W. Bauschlicher, Jr. and Louis Allamandola},
  journal={The Astrophysical Journal},
  year={2005},
  volume={632},
  pages={316 - 332}
}
This paper presents the results of an investigation of the molecular characteristics that underlie the observed peak position and profile of the nominal 6.2 μm interstellar emission band generally attributed to the CC stretching vibrations of polycyclic aromatic hydrocarbons (PAHs). It begins with a summary of recent experimental and theoretical studies of the spectroscopic properties of large (>30 carbon atoms) PAH cations as they relate to this aspect of the astrophysical problem. It then… 

The 6.2 μm band position in laboratory and astrophysical spectra: a tracer of the aliphatic to aromatic evolution of interstellar carbonaceous dust

Context. The infrared emission features observed in the mid-infrared wavelength range in astronomical objects, often called the Aromatic Infrared Bands, exhibit differences in shape and position.

THE INFRARED SPECTRA OF VERY LARGE IRREGULAR POLYCYCLIC AROMATIC HYDROCARBONS (PAHs): OBSERVATIONAL PROBES OF ASTRONOMICAL PAH GEOMETRY, SIZE, AND CHARGE

The mid-infrared (IR) spectra of six large, irregular polycyclic aromatic hydrocarbons (PAHs) with formulae (C84H24–C120H36) have been computed using density functional theory (DFT). Trends in the

Variations in the 6.2 μm emission profile in starburst-dominated galaxies: a signature of polycyclic aromatic nitrogen heterocycles (PANHs)?

Analyses of the polycyclic aromatic hydrocarbon (PAH) feature profiles, especially the 6.2 $\mu$m feature, could indicate the presence of nitrogen incorporated in their aromatic rings. In this work,

Electronic Spectra of Aromatic Hydrocarbons: A Deductive Approach to the Diffuse Interstellar Bands

Electronic Spectra of Aromatic Hydrocarbons: A Deductive Approach to the Diffuse Interstellar Bands by Gerard D. O’Connor The diffuse interstellar bands are a series of more than 500 interstellar

PROPERTIES OF POLYCYCLIC AROMATIC HYDROCARBONS IN THE NORTHWEST PHOTON DOMINATED REGION OF NGC 7023. I. PAH SIZE, CHARGE, COMPOSITION, AND STRUCTURE DISTRIBUTION

Polycyclic aromatic hydrocarbon (PAH) emission in the Spitzer Infrared Spectrograph spectral map of the northwest photon dominated region (PDR) in NGC 7023 was analyzed exclusively using PAH spectra

Effect of molecular structure on the infrared signatures of astronomically relevant PAHs

Emission bands from polycyclic aromatic hydrocarbons (PAHs) dominate the mid-infrared spectra of a wide variety of astronomical sources, encompassing nearly all stages of stellar evolution. Despite

High resolution measurements supported by electronic structure calculations of two naphthalene derivatives: [1,5]- and [1,6]-naphthyridine--estimation of the zero point inertial defect for planar polycyclic aromatic compounds.

TLDR
This work adjusted the semi-empirical relations to estimate the zero-point inertial defect of polycyclic aromatic molecules and confirmed the contribution of low frequency out-of-plane vibrational modes to the GS inertial defects of PAHs, which is indeed a key parameter to validate the analysis of such large molecules.

Theoretical infrared spectra of large polycyclic aromatic hydrocarbons.

  • A. PathakS. Rastogi
  • Physics
    Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy
  • 2007

The 6.2 μm PAH Feature and the Role of Nitrogen: Revisited

This study revisits the role that nitrogen inclusion in polycyclic aromatic hydrocarbons (PAHs; those with nitrogen inclusion, PANHs) plays in their infrared (IR) spectral properties. We present

Rotational spectroscopy of interstellar PAHs

Polycyclic aromatic hydrocarbons (PAHs) are believed to be ubiquitous in the interstellar medium. Yet, to date no specific PAH molecule has been identified. In this paper, a new observational avenue
...

References

SHOWING 1-10 OF 89 REFERENCES

The spacing of the interstellar 6.2 and 7.7 micron emission features as an indicator of polycyclic aromatic hydrocarbon size.

TLDR
A database of astrophysically relevant, infrared spectral measurements on a wide variety of neutral as well as positively and negatively charged polycyclic aromatic hydrocarbons, ranging in size from C10H8 through C48H20, is now available to extend the interstellar PAH model, and indicates that PAHs in the 50-80 carbon atom size range are entirely consistent with the observed interstellar spacing.

Direct spectroscopic evidence for ionized polycyclic aromatic hydrocarbons in the interstellar medium.

TLDR
Long-slit 8-13 micrometers spectroscopy of the nebula around NGC 1333 SVS 3 reveals spatial variations in the strength and shape of emission features that are probably produced by polycyclic aromatic hydrocarbons, providing the first identification of emission feature arising specifically from ionized PAHs in the interstellar medium.

Theoretical modeling of the infrared fluorescence from interstellar polycyclic aromatic hydrocarbons

We have modeled the family of interstellar IR emission bands at 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 microns by calculating the fluorescence from a size distribution of interstellar polycyclic aromatic

Hydrogenated polycyclic aromatic hydrocarbons and the 2940 and 2850 wavenumber (3.40 and 3.51 micron) infrared emission features.

TLDR
The 3150-2700 cm-1 (3.17-3.70 microns) range of the spectra of a number of Ar-matrix-isolated PAHs containing excess H atoms (Hn-PAHs) are presented and aliphatic C-H stretching vibrations as well as overtone and combination bands involving lower lying fundamentals are examined.

Interstellar polycyclic aromatic hydrocarbons: the infrared emission bands, the excitation/emission mechanism, and the astrophysical implications.

TLDR
The spectroscopic structure these PAHs and PAH-related materials produce in the UV portion of the interstellar extinction curve lie just below current detection limits but fall in the range detectable by the Hubble Space Telescope.

Closed-shell polycyclic aromatic hydrocarbon cations: a new category of interstellar polycyclic aromatic hydrocarbons.

The profiles of the aromatic infrared bands explained with molecular carriers

Using a compilation of the photophysical properties of molecules such as coronene, C 2 4 H 1 2 , we have constructed a numerical model to calculate the IR emission spectrum of a population of

Theoretical Modeling of Infrared Emission from Neutral and Charged Polycyclic Aromatic Hydrocarbons. I.

The nature of the carriers of the interstellar infrared (IR) emission features between 3.3 and 12.7 μm is complex. We must consider emission from a family of polycyclic aromatic hydrocarbons (PAHs)

Infrared spectroscopy of matrix-isolated polycyclic aromatic hydrocarbon cations. 4. The tetracyclic PAH isomers chrysene and 1,2-benzanthracene.

TLDR
The mid-infrared spectra of the polycyclic aromatic hydrocarbon cations of the tetracyclic isomers chrysene and 1,2-benzanthracene are presented and the strongest cation bands of these species fall between 1300 and 1330 cm-1, close to the peak of the most intense interstellar emission feature in HII regions and reflection nebulae.

Infrared spectroscopy of matrix-isolated polycyclic aromatic hydrocarbon cations. 2. The members of the thermodynamically most favorable series through coronene.

TLDR
The near- and mid-infrared spectra of the cations of the five most thermodynamically favored PAHs up to coronene are presented to test the hypothesis that these molecules are responsible for a very common family of interstellar infrared emission bands.
...