Investigation of the adsorption of CH₃I on NaCl and ice surfaces

Maxime Infuso (1, 2) , Florent Louis (1, 2) , Denis Duflot (1) , Céline Toubin (1)

1 PCMT - Physico-Chimie Moléculaire Théorique
2 PC2A - Physicochimie des Processus de Combustion et de l’Atmosphère - UMR 8522

Iodine-131 can be released during a severe nuclear accident and can be carcinogenic for humans [1]. In the literature, there are missing pieces of knowledge about inter-actions between iodinated compounds and aerosols in the troposhere. In this context,this work consists in investigating the adsorption on sea salt aerosols and ice of gaseous iodomethane (CH₂I). A force field has been parametrized and used in classical molecular dynamics calculations. This method allows to sample large systems and a wide range ofconfigurations. These configurations serve as starting geometries in a QM/QM’ ONIOM [2, 3] approach to compute the IR frequencies. In addition, periodic ab initio calculationshave been carried out [4, 5]. Adsorption energies and vibrational frequency shifts upon adsorption are thus quantified. We show that the vibrational frequency shifts are small, mainly because there is no strong coupling between the adsorbates and the surfaces. We also illustrate the differences on the adsorption between the crystal and amorphous ice at low temperature. [1] Dobyns, B. M.; Sheline, G. E.; Workman, J. B.; Tompkins, E. A.; McConahey, W. M.; Becker,D. V.J. Clin. Endocrinol. Metab., 38, 976–998 (1974) [2] Svensson, M.; Humbel, S.; Froese, R. D.; Matsubara, T.; Sieber, S.; Morokuma, K.J. Phys. Chem.,100, 19357–19363 (1996) [3] Frisch, M. J. et al. Gaussian 16 Revision B.01, Gaussian Inc. Wallingford CT (2016) [4] Giannozzi, P. et al.J. Phys. Condens. Matter, 21, 395502 (2009) [5] Giannozzi, P. et al.J. Phys. Condens. Matter,29, 465901 (2017) Acknowledgements: PIA MiRE(ANR-11-LABX-0005-01) I-SITE ULNE OVERSEE project (contract ANR-16-IDEX-004)

Domaines: Chimie théorique et/ou physique; Chimie-Physique [physics.chem-ph]

Maxime Infuso, Florent Louis, Denis Duflot, Céline Toubin. Investigation of the adsorption of CH₃I on NaCl and ice surfaces. RCP21-Rencontres de Chimie-Physique 2021-SCF21, Sep 2021, Sète, France. ⟨hal-03438358⟩