CosmicPAH-IRDB is a specialized spectroscopic database designed to study anharmonic effects in the infrared spectra of polycyclic aromatic hydrocarbons (PAHs) and related species, such as fullerenes.
It provides empirical anharmonicity functions that characterize the temperature-dependent evolution of band positions and widths. These functions are essential for modeling the emission spectra of PAHs in astrophysical environments, enabling more accurate simulations of their behavior under varying conditions.
CosmicPAH-IRDB is part of the Cosmic PAH Portal.
CosmicPAH-IRDB is open to including different types of spectra, subject to the willingness of their authors to contribute :
Experimental Data:
Systematic studies performed using the ESPOIRS setup at IRAP [1]. The spectra were analyzed using cosmicPAHmfit , a multi-component fitting tool that decomposes vibrational bands into pseudo-Voigt profiles to derive empirical anharmonicity functions.
IR multiphoton dissociation of cationic PAHs obtained at FELIX [2, 3].
Theoretical Anharmonic Spectra:
AnharmoniCaOs spectra and band assignment [4, 5]
Molecular dynamics simulations using deMonNano [5-7].
Credits:
When using the data, please cite the reference(s) associated with the publicly available dataset.
To cite the database and the CosmicPAHmfit tool, please use the reference: De Bentzmann et al. 2026, in prep.
For further acknowledgment: "The cosmicPAH-IRDB database and the cosmicPAHmfit tool are part of the Cosmic PAH portal :https://cosmic-pah.irap.omp.eu/, supported by CNRS, CNES, the ERC (project NANOCOSMOS), IRAP, OMP and Université de Toulouse."
News:
24/07/2026 : release of datasets associated with publications [1,5].
References:
Demyk K., Joblin C., de Bentzmann L., Toublanc D., Mulas G., 2016, « Infrared spectroscopy of gas-phase hydrogenated and methylated pyrene », submitted to A&A, DOI : 0.48550/arXiv.2607.16018
Oomens J., van Roij, A. J. A., Meijer, G., von Helden, G., 2000, « Gas-Phase Infrared Photodissociation Spectroscopy of Cationic Polyaromatic Hydrocarbons», ApJ 542, 404-410, DOI: 10.1086/309545
Oomens J., Tielens A. G. G. M., Sartakov B. G., von Helden, G., Meijer G., 2003, « Laboratory Infrared Spectroscopy of Cationic Polycyclic Aromatic Hydrocarbon Molecules », ApJ 591, 968-985, DOI : 10.1086/375515
Mulas G., Falvo C., Cassam-Chenaï P., Joblin C., 2018, « Anharmonic vibrational spectroscopy of PAH », J. Chem. Phys. 149, 144102 (16pp), DOI: 10.1063/1.5050087, hal-01890989
Chakraborty S., Mulas G., Rapacioli M., Joblin,C., « Modeling Anharmonic Infrared Spectra of Thermally Excited Pyrene (C16H10): the combined view of DFT AnharmonicCaOs and approximate DFT molecular dynamics », 2021, J. Mol. Spec. 378, 111466, DOI: 10.1016/j.jms.2021.111466, hal-03228099, arXiv: 2102.06582
Joalland B., Rapacioli M., Simon A., Joblin C., Marsden C. J., and Spiegelman F., 2010, « Molecular dynamics simulations of anharmonic infrared spectra of [SiPAH]+ complexes », J. Phys. Chem. A 114, 5846-5854, DOI: 10.1021/jp911526n, hal-00843706
Simon A., Rapacioli, M., Lanza, M., Joalland B., Spiegelman F., 2011, Phys. Chem. Chem. Phys. 13, 3359, DOI: 10.1039/C0CP00990C
Funding:
This work was supported by :
The European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013) ERC-2013-SyG, Grant agreement No610256 NANOCOSMOS,
The CNES (APR LAIBrary/JWST),
Université de Toulouse,
The Thematic Action “Physique et Chimie du Milieu Interstellaire” (PCMI) of the INSU Programme National “Astro”, with contributions from CNRS Physique, CNRS Chimie, CEA, and CNES.
