Year: 2026
Type: preprint
Abstract: The trihydrogen cation ($\mathrm{H_3^+}$) initiates the ion-molecule reactions that build molecular complexity in interstellar space. Whether its canonical formation reaction, $\mathrm{H_2^+ + H_2 \rightarrow H_3^+ + H}$, proceeds on inorganic surfaces under radiation-driven ionization has remained untested. Here we drive $\mathrm{H_3^+}$ formation on hydrated silica nanoparticles using intense 1.88 keV X-ray pulses, combining ion velocity map imaging, electron time-of-flight spectroscopy, and single-particle coherent diffractive imaging to resolve this chemistry on individual particles. The self-induced surface electric field on the V/nm scale drives interfacial charge transfer and water fragmentation. This field is the dominant parameter governing the relative yields of $\mathrm{H^+}$, $\mathrm{H_2^+}$, and $\mathrm{H_3^+}$ across particle size, composition, and aggregation. Density functional theory and nonadiabatic quantum molecular dynamics simulations trace this field-driven charge transfer, directly analogous to band bending at semiconductor photoelectrodes. These results establish surface-field-driven charge transfer as a unifying mechanism between radiation dominated astrophysical environments and field-driven surface catalysis.
Source: arXiv (Cornell University)
Authors: Sahel-Schackis, Samuel, Summers, Adam, Dagar, Ritika, Feinberg, Alexandra, Grassl, Martin, Dold, Simon, Boll, Rebecca, Ovcharenko, Yevheniy, Aikens, Chris, Vera, Cesar Costa, De Fanis, Alberto, Duley, Avijit, Gerke, Felix, Jost, Daniel, Leiner, Regina, Meyer, Michael, Molesky, Ilana J. P., Obaid, Razib, Powell, Jeffrey, Rennhack, Nils, Senfftleben, Björn, Tackenberg, Hendrik, Tuemmler, Paul, Usenko, Sergey, Peltz, Christian, Fennel, Thomas, Gallei, Markus, Rühl, Eckart, Rudenko, Artem, Rolles, Daniel, Linker, Thomas, Kling, Matthias F.
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7201855444
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