The kinetic energy distributions of carbon ions for 'anomalous' fragmentation channels where carbon is charged higher than selenium

<p><strong>Figure 5.</strong> The kinetic energy distributions of carbon ions for 'anomalous' fragmentation channels where carbon is charged higher than selenium. For both, methylselenol (a) and ethylselenol (b), these channels are compared with the typical final states, where selenium is charged higher than carbon. Vertical lines of the same colour indicate simulated Coulomb explosion energies for the given charge states assuming the equilibrium geometry of the respective neutral molecule.</p> <p><strong>Abstract</strong></p> <p>The ionization and fragmentation of two selenium containing hydrocarbon molecules, methylselenol (CH₃SeH) and ethylselenol (C₂H₅SeH), by intense (>10¹⁷ W cm⁻²) 5 fs x-ray pulses with photon energies of 1.7 and 2 keV has been studied by means of coincident ion momentum spectroscopy. Measuring charge states and ion kinetic energies, we find signatures of charge redistribution within the molecular environment. Furthermore, by analyzing fragment ion angular correlations, we can determine the laboratory-frame orientation of individual molecules and thus investigate the fragmentation dynamics in the molecular frame. This allows distinguishing protons originating from different molecular sites along with identifying the reaction channels that lead to their emission.