Bouthéïna Kerkeni

@article{thatte_4055,

title = {The PAH 3.4 micron feature as a tracer of shielding in the Orion Bar and NGC 6240},

author = {Niranjan Thatte and Dimitra Rigopoulou and Fergus R Donnan and Ismael Garcia-Bernete and Miguel Pereira-Santaella and Bruce Draine and Oscar Veenema and Bouthéïna Kerkeni and Almudena Alonso-Herrero and Hermosa Muñoz Laura and Gabriela Speranza},

url = {https://doi.org/10.1093/mnras/staf2047},

year  = {2026},

date = {2026-11-01},

journal = {Monthly Notices Of The Royal Astronomical Society},

volume = {545},

number = {1},

pages = {1-10},

abstract = {We have carried out a detailed analysis of the 3.4 ?m spectral feature arising from Polycyclic Aromatic Hydrocarbons (PAH),

using James Webb Space Telescope archival data. For the first time in an external galaxy (NGC 6240), we have identified two

distinct spectral components of the PAH 3.4 ?m feature: a shorter wavelength component at 3.395 ?m, which we attribute to

short aliphatic chains tightly attached to the aromatic rings of the PAH molecules; and a longer wavelength feature at 3.405 ?m

that arises from longer, more fragile, aliphatic chains that are weakly attached to the parent PAH molecule. These longer chains

are more easily destroyed by far-ultraviolet photons (>5 eV) and PAH thermal emission only occurs where PAH molecules

are shielded from more energetic photons by dense molecular gas. We see a very strong correlation in the morphology of the

PAH 3.395 ?m feature with the PAH 3.3 ?m emission, the latter arising from robust aromatic PAH molecules. We also see an

equally strong correlation between the PAH 3.405 ?m morphology and the warm molecular gas, as traced by H2 vibrational

lines. We show that the flux ratio PAH 3.395/PAH 3.405 < 0.3 corresponds strongly to regions where the PAH molecules are

shielded by dense molecular gas, so that only modestly energetic UV photons penetrate to excite the PAHs. Our work shows that

PAH 3.405 ?m and PAH 3.395 ?m emission features can provide robust diagnostics of the physical conditions of the interstellar

medium in external galaxies, and can be used to quantify the energies of the photon field penetrating molecular clouds.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{barzaga_4080,

title = {Peculiarities in the infrared emission of polycyclic aromatic hydrocarbon-C60 adducts},

author = {Ransel Barzaga and Bouthéïna Kerkeni and Domingo Anibal García-Hernández and Xavier Ribas and Tania Pelachs and Minia Manteiga and Arturo Manchado and Marco Gómez-Muñoz and Teresa Huertas-Roldán and Ghofrane Ouerfelli},

url = {https://doi.org/10.1051/0004-6361/202554031},

year  = {2025},

date = {2025-12-01},

journal = {Astronomy & Astrophysics},

volume = {704},

number = {A&A},

pages = {20},

abstract = {The coexistence of polycyclic aromatic hydrocarbons (PAHs) and the C60 fullerene in different astrophysical environments can give rise to the formation of new complex species denoted as PAH-C60 adducts, which may contribute to the infrared (IR) emission observed. These PAH-C60 adducts have previously been reported experimentally due to the high reactivity between PAHs and C60. From an astrophysical point of view, however, they have not been considered in detail yet. Here, we performed a combined experimental and theoretical study in order to characterize the IR spectra of PAH-C60 adducts, including multiple adducts. Using new advanced experimental techniques, we were able to synthesize some specific PAH-C60 adduct isomers and measure their IR spectra. These experimental data were used to correct their harmonic scaled spectra, as obtained from quantum-chemistry calculations performed at the density functional theory (DFT) level under the B3LYP-GD3/6-31+G(d) approach. This way, we simulated the IR (~3-25 ?m) spectra of multiple PAH-C60 adducts, composed by a different number of PAH units: mostly one or two units. In addition, the chemical kinetics data available in the literature were used to tentatively estimate the possible order of magnitude of the abundances of these PAH-C60 adducts using the available observational data. Essentially, our results revealed a possible strong modification of the IR spectra when astronomically estimated abundances are considered. Several spectral peculiarities are observed, such as a broad ~3.4-3.6 ?m feature, and important modifications in the 6-10 and 12-16 ?m spectral regions together with contributions to the C60 features at 7.0 and 18.9 ?m. Interestingly, these PAH-C60 adducts lack aliphatic CH bonds, but they display IR features around 3.4 ?m, challenging previous interpretations of this astronomical feature.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}