Abstract
The ultrafast nuclear and electronic dynamics of protonated water clusters H+(H2O)n after extreme ultraviolet photoionization is investigated. In particular, we focus on cluster cations with n = 3, 6, and 21. Upon ionization, two positive charges are present in the cluster related to the excess proton and the missing electron, respectively. A correlation is found between the cluster's geometrical conformation and initial electronic energy with the size of the final fragments produced. For situations in which the electron hole and proton are initially spatially close, the two entities become correlated and separate in a time-scale of 20 to 40 fs driven by strong non-adiabatic effects.
Highlights
No time-resolved XUV photoionization experiments have been performed for these systems up to date, full quantum dynamics10 and mixed quantum-classical molecular dynamics calculations11 revealed extremely fast correlations between the excess proton and the electron hole for the HðH2OÞ22þ cation related to strong non-Born-Oppenheimer effects
Not much is yet known about the detailed fragmentation channels and the time-resolved dynamics of ionized protonated water clusters, specially how the positive charges related to an excess proton and an electron hole separate and in what time scale and in what conditions the electron hole results in neutral radical fragments while a new solvated proton is released into the system
We have investigated the ultrafast nuclear and electronic dynamics of protonated water clusters Hþ(H2O)n upon single photoionization by XUV radiation in the photon energy range between 10 and 25 eV, in which outer valence electrons can become ionized, by surfacehopping molecular dynamics simulations
Summary
Protonated water clusters of general formula Hþ(H2O)n constitute an important model of the solvated proton in liquid water. The fact that clusters of the desired size can be prepared and controlled in the gas phase has made possible multitude of spectroscopic and fragmentation dynamics studies on clusters featuring the excess proton motif. Coincidence measurement experiments without time information and based on the detection of fragmentation products on small clusters H3Oþ and Hþ(H2O) have revealed the probabilities for different fragmentation channels upon valence photoionization as well as kinetic energy releases of the fragments.. No time-resolved XUV photoionization experiments have been performed for these systems up to date, full quantum dynamics and mixed quantum-classical molecular dynamics calculations revealed extremely fast correlations between the excess proton and the electron hole for the HðH2OÞ22þ cation related to strong non-Born-Oppenheimer effects. Not much is yet known about the detailed fragmentation channels and the time-resolved dynamics of ionized protonated water clusters, specially how the positive charges related to an excess proton and an electron hole separate and in what time scale and in what conditions the electron hole results in neutral radical fragments while a new solvated proton is released into the system. The shape of the cluster and the initial water molecule which is ionized determine as well whether the electron hole can escape the system in the form of a H2Oþ cation or whether the charge and spin separate yielding OH or other neutral fragments. In the Appendix, we briefly describe the blockwise coupling scheme for the fewest-switching surface hopping method that was employed in this work and its convergence properties are shown on a simple model Hamiltonian
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
