Related papers: Dehydrogenated polycyclic aromatic hydrocarbons an…
Polycyclic Aromatic Hydrocarbon (PAH) molecules have been long adjudged to contribute to the frequently detected distinct emission features at 3.3, 6.2, 7.7, 8.6, 11.2 and 12.7 {\mu}m with weaker and blended features distributed in the 3-20…
We present a charge distribution based model that computes the infrared spectrum of polycyclic aromatic hydrocarbon (PAH) molecules using recent measurements or quantum chemical calculations of specific PAHs. The model is applied to a…
Various studies have emphasized variations of the charge state and composition of the interstellar polycyclic aromatic hydrocarbon (PAH) population in photodissociation regions (PDRs). We aim to model the spatial evolution of the charge and…
The 11.2 $\mu$m emission band belongs to the family of the `Unidentified' Infrared (UIR) emission bands seen in many astronomical environments. In this work we present a theoretical interpretation of the band characteristics and profile…
We present a systematic study of mid-infrared spectra of galaxies including star-forming galaxies and Active Galactic Nuclei observed with JWST MIRI-MRS and NIRSpec-IFU. We focus on the relative variations of the 3.3, 6.2, 7.7, 11.3, 12.7…
We introduce a novel model to spectroscopically constrain the mid-infrared (MIR) extinction/attenuation curve from 3--17 um, using Polycyclic Aromatic Hydrocarbon (PAH) emission drawn from an AKARI-Spitzer extragalactic cross-archival…
A large number of interstellar absorption features at ~ 4000\AA\ -- 1.8 {\mu}m, known as the "diffuse interstellar bands" (DIBs), remains unidentified. Most recent works relate them to large polycyclic aromatic hydrocarbon (PAH) molecules…
A recent study of soft X-ray absorption in native and hydrogenated coronene cations, C$_{24}$H$_{12+m}^+$ $m=0-7$, led to the conclusion that additional hydrogen atoms protect (interstellar) Polycyclic Aromatic Hydrocarbon (PAH) molecules…
We report the results of a search for emission features from interstellar deuterated polycyclic aromatic hydrocarbons (PAHs) in the 4um region with the Infrared Camera (IRC) onboard AKARI. No significant excess emission is seen in 4.3-4.7um…
The formation of polycyclic aromatic hydrocarbons (PAHs) and their methyl derivatives occurs mainly in the dust shells of asymptotic giant branch (AGB) stars. The bands at 3.3 and 3.4 $\mu$m, observed in infrared emission spectra of several…
Polycyclic aromatic hydrocarbon (PAH) molecules have been long considered promising candidates for the carriers of the diffuse interstellar bands (DIBs). The PAH-DIB hypothesis, however, raises two major issues. First, the number of…
Following our initial discovery of blue luminescence in the spectrum of the Red Rectangle (RR) and its identification as fluorescence by small three- to four-ringed polycyclic aromatic hydrocarbon (PAH) molecules, we report on the spatial…
Polycyclic aromatic hydrocarbons (PAHs) are responsible for a variety of near- and mid-infrared spectral features in Galactic and extragalactic sources. A feature at 1.05 $\mu$m arising from electronic transitions in PAH cations is…
We present recent UV laboratory spectra of various polycyclic aromatic hydrocarbons (PAHs) and explore the potential of these molecules as carriers of the DIBs. From a detailed comparison of gas-phase and Ne-matrix absorption spectra of…
This work proposes deuteronated PAH (DPAH+ ) molecules as a potential carrier of the 4.4 and 4.65 {\mu}m mid infrared emission bands that have been observationally detected towards the Orion and M17 regions. Density Functional Theory…
The gas-phase abundances of deuterium (D) in the local interstellar medium (ISM) exhibit considerable regional variations. Particularly, in some regions the gas-phase D abundances are substantially lower than the primordial D abundance…
Dust attenuation curves in external galaxies are useful to study their dust properties as well as to interpret their intrinsic spectral energy distributions. In particular the presence or absence of a UV bump at 2175 A remains an open issue…
This work presents theoretical calculations of infrared spectra of nitrogen (N)-containing polycyclic aromatic hydrocarbon (PAH) molecules with incorporation of N, NH and NH$_2$ using density functional theory (DFT). The properties of their…
The 2175{\AA} bump is a prominent absorption feature at ultraviolet (UV) wavelengths in dust extinction and attenuation curves. Understanding the relative strength of this feature is important for accurate dust corrections at both low- and…
The mid-IR spectra of six large, irregular PAHs with formulae (C84H24 - C120H36) have been computed using Density Functional Theory (DFT). Trends in the dominant band positions and intensities are compared to those of large, compact PAHs as…