Unravelling molecular interactions in uracil clusters by XPS measurements assisted by ab initio and tight-binding simulations

Giuseppe Mattioli (1) , Lorenzo Avaldi (1) , Paola Bolognesi (1) , John D Bozek (2) , Mattea C Castrovilli (1) , Jacopo Chiarinelli (1) , Alicja Domaracka (3) , Suvasthika Indrajith (3) , Sylvain Maclot (4, 5) , Aleksandar R. Milosavljević (2) , Chiara Nicolafrancesco (2, 3) , Christophe Nicolas (2) , Patrick Rousseau (3)

1 CNR-ISM - Istituto di Struttura della Materia
2 SSOLEIL - Synchrotron SOLEIL
3 CIMAP - UMR 6252 - Centre de recherche sur les Ions, les MAtériaux et la Photonique
4 Skane University Hospital [Lund]
5 KTH - KTH Royal Institute of Technology [Stockholm]

The C, N and O 1s XPS spectra of uracil clusters in the gas phase have been measured. A new bottom-up approach, which relies on computational simulations starting from the crystallographic structure of uracil, has been adopted to interpret the measured spectra. This approach sheds light on the different molecular interactions (H-bond, π-stacking, dispersion interactions) at work in the cluster and provides a good understanding of the observed XPS chemical shifts with respect to the isolated molecule in terms of intramolecular and intermolecular screening occurring after the core–hole ionization. The proposed bottom-up approach, reasonably expensive in terms of computational resources, has been validated by finite-temperature molecular dynamics simulations of clusters composed of up to fifty molecules.

Domaines: Chimie théorique et/ou physique

Giuseppe Mattioli, Lorenzo Avaldi, Paola Bolognesi, John D Bozek, Mattea C Castrovilli, et al.. Unravelling molecular interactions in uracil clusters by XPS measurements assisted by ab initio and tight-binding simulations. Scientific Reports, 2020, 10, pp.13081. ⟨10.1038/s41598-020-69947-3⟩. ⟨hal-02989768⟩