Coulomb Explosion of Large Polyatomic Molecules Assisted by Nonadiabatic Charge Localization

The electron-nuclear dynamics of the Coulomb explosion of a large polyatomic molecule, anthracene, is probed using kinetic energy distributions of produced H⁺ ions. The kinetic energy release of ejected protons exceeds 30 eV for anthracene exposed to 10¹⁴  W cm^-2, 800 nm pulses of 60 fs duration. We propose a strong-field charge localization model, based on nonadiabatic dynamics of charge distribution in a (multiply) ionized molecule; the charge localization lasts many laser periods and is sustained through successive ionizations of the molecular ion. The model explains quantitatively the dependence of the H⁺ kinetic energy on the laser intensity. Dissociative ionization of a polyatomic molecule enabled by long-lived charge localization is a new type of electron-nuclear dynamics and is essential for understanding the pathways of molecular or ionic fragmentation in strong fields.