title: Identifying Cytosine-Specific Isomers via High-Accuracy Single Photon Ionization.
abstract: Biological entities, such as DNA bases or proteins, possess numerous tautomers and isomers that lie close in energy, making the experimental characterization of a unique tautomer challenging. We apply VUV synchrotron-based experiments combined with state-of-the-art ab initio methodology to determine the adiabatic ionization energies (AIEs) of specific gas-phase cytosine tautomers produced in a molecular beam. The structures and energetics of neutral and cationic cytosine tautomers were determined using explicitly correlated methods. The experimental spectra correspond to well-resolved bands that are attributable to the specific contributions of five neutral tautomers of cytosine prior to ionization. Their AIEs are experimentally determined for the first time with an accuracy of 0.003 eV. This study also serves as an important showcase for other biological entities presenting a dense pattern of isomeric and tautomeric forms in their spectra that can be investigated to understand the charge redistribution in these species upon ionization.
authors.affiliation: Department of Biology and Chemistry, City University of Hong Kong , Kowloon, Hong Kong.
authors.forename: Ziyong
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Biology and Chemistry, City University of Hong Kong , Kowloon, Hong Kong.
authors.forename: Kai-Chung
authors.identifier: 0000-0003-2125-6841
authors.initials: KC
authors.lastname: Lau
authors.affiliation: Synchrotron SOLEIL , L'orme des Merisiers, Saint-Aubin - BP 48, 91192 Gif-sur-Yvette Cedex, France.
authors.forename: Gustavo A
authors.identifier: 0000-0003-2915-2553
authors.initials: GA
authors.lastname: Garcia
authors.affiliation: Synchrotron SOLEIL , L'orme des Merisiers, Saint-Aubin - BP 48, 91192 Gif-sur-Yvette Cedex, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Nahon
authors.affiliation: Synchrotron SOLEIL , L'orme des Merisiers, Saint-Aubin - BP 48, 91192 Gif-sur-Yvette Cedex, France.
authors.forename: Dušan K
authors.initials: DK
authors.lastname: Božanić
authors.affiliation: LIDYL, CEA, CNRS, Université Paris-Saclay, CEA Saclay , F-91191 Gif-sur-Yvette, France.
authors.forename: Lionel
authors.identifier: 0000-0002-7131-968X
authors.initials: L
authors.lastname: Poisson
authors.affiliation: Chemistry Department, Faculty of Science, King Saud University , P.O. Box 2455, Riyadh 11451, Kingdom of Saudi Arabia.
authors.forename: Muneerah Mogren
authors.initials: MM
authors.lastname: Al-Mogren
authors.affiliation: Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), UMR 7583 CNRS, Universités Paris-Est Créteil et Paris Diderot , 61 Avenue du Général de Gaulle, 94010 Créteil, France.
authors.forename: Martin
authors.initials: M
authors.lastname: Schwell
authors.affiliation: Department of Chemistry, University of Nebraska-Lincoln . 433 Hamilton Hall, Lincoln, Nebraska 68588-0304, United States.
authors.forename: Joseph S
authors.initials: JS
authors.lastname: Francisco
authors.affiliation: Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, Université Paris-Est. 5 bd Descartes, 77454 Marne-la-Vallée, France.
authors.forename: Ayad
authors.initials: A
authors.lastname: Bellili
authors.affiliation: Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, Université Paris-Est. 5 bd Descartes, 77454 Marne-la-Vallée, France.
authors.forename: Majdi
authors.identifier: 0000-0002-4737-7978
authors.initials: M
authors.lastname: Hochlaf
mesh_terms: D003596:Cytosine / Q000737:chemistry*; D007536:Isomerism; D055668:Photochemical Processes; D017785:Photons
chemical_list: D003596:Cytosine