Time–Energy Uncertainty and Electronic Correlation in H<sup>+</sup>–Graphite Collisions

Bonetto, F.; Romero, Marcelo Ariel; Iglesias-García, A.; Vidal, R.; Goldberg, E. C.

doi:10.1021/jp511339v

Cited by 23 publications

(38 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The bond-pair model has been successfully used in many different projectile-target combinations [12][13][14][15][16][17]. The atom energy and the hopping terms are obtained from a model Hamiltonian for the atom-surface adiabatic interaction based on both the localized atom-atom interactions and the extended features of the surface states [11].…”

Section: A Atom-surface Interaction: Bond-pair Modelmentioning

confidence: 99%

“…In the present work we study the charge transfer between positive ions of Sr and Mg and an Au surface at low incoming energies. Both systems are described by an Anderson Hamiltonian projected over the most probable atomic configurations and the Hamiltonian terms are calculated by using our bondpair model [11], which has proved to be successful in a great variety of interacting systems (see for example [12][13][14][15][16][17] and references therein).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Signals of strong electronic correlation in ion scattering processes

Bonetto

González²,

Goldberg

2016

Phys. Rev. B

View full text Add to dashboard Cite

Previous measurements of neutral atom fractions for Sr + scattered by gold polycrystalline surfaces show a singular dependence with the target temperature. There is still not a theoretical model that can properly describe the magnitude and the temperature dependence of the neutralization probabilities found. Here, we applied a first-principles quantum-mechanical theoretical formalism to describe the time-dependent scattering process. Three different electronic correlation approaches consistent with the system analyzed are used: (i) the spinless approach, where two charge channels are considered (Sr 0 and Sr + ) and the spin degeneration is neglected; (ii) the infinite-U approach, with the same charge channels (Sr 0 and Sr + ) but considering the spin degeneration; and (iii) the finite-U approach, where the first ionization and second ionization energy levels are considered very, but finitely, separated. Neutral fraction magnitudes and temperature dependence are better described by the finite-U approach, indicating that e-correlation plays a significant role in charge-transfer processes. However, none of them is able to explain the nonmonotonous temperature dependence experimentally obtained. Here, we suggest that small changes in the surface work function introduced by the target heating, and possibly not detected by experimental standard methods, could be responsible for that singular behavior. Additionally, we apply the same theoretical model using the infinite-U approximation for the Mg-Au system, obtaining an excellent description of the experimental neutral fractions measured.

show abstract

Section: A Atom-surface Interaction: Bond-pair Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Signals of strong electronic correlation in ion scattering processes

Bonetto

González²,

Goldberg

2016

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…But, from the comparison, we extract clearly that the pronounced oscillatory behavior is introduced by the correlated nature of the three possible charge states of hydrogen. Furthermore, the negative hydrogen formation reaches higher values than the measured ones in clean carbon based surfaces such as highly oriented pyrolitic graphite (HOPG) [26,42].…”

Section: Finite-u Calculation Of the Dynamical Collision Processmentioning

confidence: 81%

Hydrogen ion scattering from a potassium impurity adsorbed on graphene

et al. 2019

View full text Add to dashboard Cite

In this work we study the charge exchange process in the scattering of protons by potassium atoms adsorbed on a graphene surface in a low coverage limit. Both, the projected density of states on the alkaline atom site and the final charge states of the hydrogen projectile are calculated by considering the electronic Coulomb repulsion in the s-valence orbital. The inner 3p and 3s states of potassium are included and the local perturbations of the density matrix on the surrounding C atoms are also considered. The interacting systems are described by an Anderson Hamiltonian whose terms are calculated from the chemical properties of the atoms and the extended features of the graphene surface. The positive and negative ion fractions of hydrogen in the collision process are obtained from Keldysh-Green functions, which are calculated by employing the equation of motion method closed up to a second order in the atom-surface coupling term. It is found that the carbon atoms have no possibility of a direct charge exchange process in a frontal collision of the proton with the K adatom, and that the K-3p band, broadened by the interaction with the graphene surface, provides an important source of electrons for the negative ionization of hydrogen, which is also promoted by the presence of a K-3s core state. The narrow 4s and 3p bands of the adsorbed potassium lead to an oscillatory dependence with the projectile incoming energy, of the probability for the three correlated charge states of hydrogen.

show abstract

“…A nonmonotonous energy dependence of the charge transfer was found in the scattering from pristine graphene and from HOPG [23,34]. In these projectile/surface systems: Li/graphene and H/HOPG, the charge fractions dependence on the incoming energy are related to the suppression of the hybridization width.…”

Section: Final Charge States Of the Projectilementioning

confidence: 95%

Collision of protons with carbon atoms of a graphene surface in the presence of adsorbed potassium

et al. 2020

View full text Add to dashboard Cite

In this work we study the frontal collision of protons with the carbon atoms of a graphene surface with a low coverage of adsorbed potassium. It is aimed at the analysis of the effect of the adsorbates in both charge exchange and electron emission processes, when the binary collision occurs between the proton and a carbon atom of the surface. The frontal collision with the K adsorbate, already analyzed and discussed in a previous work, is compared with the frontal collision with different carbon neighbors. In the present work we studied the signals, due to the localized structures in the density matrix of the composed graphene plus potassium surface, that can be distinguished when the collision occurs either with the adsorbate, a nearby carbon atom, or a carbon atom that does not feel the presence of the adsorbate. The interacting system is described by the Anderson Hamiltonian which takes into account the electronic repulsion on the projectile site; the charge fractions, the energy distribution of electrons in the solid, and the electron emission after the collision are calculated by using the nonequilibrium Green-Keldysh functions formalism solved by the equation of motion method. In the binary collision with a carbon atom, the extended features of the band structure of graphene smooth the dependence of the projectile charge fractions on the incoming energy and notably decrease the negative ions formation. The localized structures of the density of matrix caused by the presence of the adsorbate are perceptible for scattered carbon atoms close to K. The intense emission of low energy electrons obtained in the case of the scattering by potassium is fundamentally associated with the very localized K-4s empty band. This characteristic, although less marked, remain in the scattering by nearby carbon atoms, due to both the interaction with K along the projectile trajectory and the perturbed local density of states on the carbon atoms due to the adsorbate presence. In addition, the extended nature of the electronic structure of graphene allows for the emission of more energetic electrons.

show abstract

Time–Energy Uncertainty and Electronic Correlation in H⁺–Graphite Collisions

Cited by 23 publications

References 51 publications

Signals of strong electronic correlation in ion scattering processes

Signals of strong electronic correlation in ion scattering processes

Hydrogen ion scattering from a potassium impurity adsorbed on graphene

Collision of protons with carbon atoms of a graphene surface in the presence of adsorbed potassium

Contact Info

Product

Resources

About

Time–Energy Uncertainty and Electronic Correlation in H+–Graphite Collisions

Cited by 23 publications

References 51 publications

Signals of strong electronic correlation in ion scattering processes

Signals of strong electronic correlation in ion scattering processes

Hydrogen ion scattering from a potassium impurity adsorbed on graphene

Collision of protons with carbon atoms of a graphene surface in the presence of adsorbed potassium

Contact Info

Product

Resources

About

Time–Energy Uncertainty and Electronic Correlation in H⁺–Graphite Collisions