arXiv subjects

Guillermo Hinojosa

Publications and source records attributed to Guillermo Hinojosa.

3 recordsLinked to original sources

arXiv2026

Highly correlated electronic bounding and spin effect: confirmation of an autodetaching state of O$^-$

The existence of an auto-detaching state of O$^-$ with a lifetime on the scale of a hundred nanoseconds is demonstrated both experimentally and theoretically. The O$^-$ lifetime values are determined using two recently developed methods. The experimental approach is based on a derivation from measured electron-loss cross sections combined with time-of-flight spectrometry. For the theoretical approach, the continued Green's function within the formalism of Fano-Feshbach is applied. We present the measured lifetime value of $100 \pm 10 \text{ ns}$. The calculated lifetime value is 75 ns, and is associated with the (2p$^3$3s$^2$)$^4$S state of O$^-$. We discuss how the existence of a 100-ns-lifetime oxygen metastable anion can impact the modeling of oxygen-containing systems.

physics.atom-ph↗

arXiv2022

Photoionization of chlorine, sulfur, phosphorus and a hypothesis to quench metastable states

The objective of our proposal is to study the photoionization of Chlorine, Sulfur, and Phosphorus ions using the unique high resolution capability of 10.0.1 beamline in the ALS. These species are relevant in astrophysics and as a benchmark for state of the art theoretical models of the quantum properties of ions. We also propose to test a technique to quench the metastable states from the ion-beam based on recent experimental evidence and on a well known technique in chemistry. The work of this proposal may lay the foundations for a definite solution to control the metastable component of the initial ion-beam.

physics.atom-ph↗

arXiv2019

Solving the CH$_4^-$ riddle: the fundamental role of spin to explain metastable anionic methane

When atoms or molecules exist in the form of stable negative ions, they play a crucial role in the gas phase chemistry. Determining the existence of such an ion, its internal energy and its stability are necessary prerequisites to analyze the role of this ion in a particular medium. Experimental evidence of the existence of a negative methane ion CH$_4^-$ has been provided over a period of 50 years. However, quantum chemistry had not been able to explain its existence, and a detailed recent study has shown that the experimentally observed species cannot be described by the attachement of an electron in the ground state of CH$_4^-$. Here we describe CH$_4^-$ as being a metastable species in its lowest quartet spin state and we find that this species is a CH$_2^-$-:H$_2$ exciplex with three open shells, lying 5.8 eV above the methane singlet ground state but slightly below the dissociation fragments. The formation of charged exciplexes is a novel mechanism to explain small molecular anions with implications in a plethora of basic and applied research fields.

physics.chem-ph↗