Cassidy<i>et al</i>Reply:

Cassidy, D. B.; Bromley, Michael W. J.; Cota, L. C.; Hisakado, T. H.; Tom, H. W. K.; Mills, A. P.

doi:10.1103/physrevlett.106.209302

Cited by 57 publications

(141 citation statements)

References 2 publications

Supporting

Mentioning

130

Contrasting

Order By: Relevance

“…The formation of Ps via this mechanism depends on the availability of surface electrons, which may be produced either thermally [35] or by laser irradiation [36]. The former process involves the thermal activation of electrons to surface states, the existence of which is dependent on the presence of a positron, which means that the temperature dependence of Ps emission from Si looks almost identical to thermal activation curves obtained from metal samples [37].…”

Section: Introductionmentioning

confidence: 58%

“…Lifetime and laser spectroscopy has revealed that the emission of Ps from the surface of p-Si(100) does not, for the most part, occur via the usual channels for metals or semiconductors [35] described above (i.e., direct capture of electrons by energetic positrons or thermal desorption of Ps from a positronic surface state [24]). Rather, Ps from this material is mostly emitted via the formation of an intermediate surface electron-positron bound state that appears to be analogous to the surface exciton (that is, an electron bound to a hole in the surface band) observed by Weinelt et al [36].…”

Section: Introductionmentioning

confidence: 99%

“…However, if there is a positron present on the surface, as may be the case just after the implantation of a positron pulse, then these electrons may form positronium via a similar mechanism. It turns out that such Ps is emitted spontaneously, with a constant energy of ~ 0.16 eV [35,38], that is determined by the particular electron and positron energy levels of the system.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Positronium formation via excitonlike states on Si and Ge surfaces

et al. 2011

Self Cite

View full text Add to dashboard Cite

Recent experiments combining lifetime and laser spectroscopy of positronium (Ps) show that these atoms are emitted from p-Si(100) at a rate that depends on the sample temperature, suggesting a thermal activation process, but with an energy that does not, precluding direct thermal activation as the emission mechanism. Moreover, the amount of Ps emitted is substantially increased if the target is irradiated with 532 nm laser light just prior to the implantation of the positrons. Our interpretation of these data was that the Ps was emitted via an exciton-like positron-electron surface state, not dissimilar to an electronic surface exciton observed on Si in two-photon photoemission measurements. The hypothesis that this state may be populated by electrons from one of the occupied electronic surface states, either thermally or by laser excitation, is consistent with our observations and suggests that one should expect a high Ps yield at room temperature from an n-doped Si(100) sample, since in this case the same surface states will already be occupied. Here we present data obtained with an n-Si(100) target that supports our model, and also reveals the unexpected result that the kinetic energy of Ps emitted from this material actually decreases when it is heated, an effect we attribute to shifts in the surface energy levels due to the presence of a high density of thermally generated electrons. We show data obtained with a Ge(100) sample that corroborate the idea that the effects we observe are related to surface electron states, and hence should occur for any indirect band gap semiconductor with dangling bond states. Our model is further confirmed by the observation that the Ps yield from p-Si depends linearly on the surface density of the implanted positrons due to the effects of electron-hole pairs created as the positrons slow down.

show abstract

Section: Introductionmentioning

confidence: 58%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Positronium formation via excitonlike states on Si and Ge surfaces

et al. 2011

Self Cite

View full text Add to dashboard Cite

show abstract

“…There is an intense interest in studying the electronic properties of atoms trapped in fullerenes, carbon nanotubes, or nanopores (Jaskolski, 1996). Recent experiments, for example, measured the energy spectrum of Ps atoms confined in 5 nm diameter silicon nanopores (Cassidy et al, 2011). Accurate ECG calculations would probably be able to explain the dependence of the measured 1S-2P transition on the radius of the cavity.…”

Section: G Outlookmentioning

confidence: 99%

Theory and application of explicitly correlated Gaussians

et al. 2013

View full text Add to dashboard Cite

The variational method complemented with the use of explicitly correlated Gaussian basis functions is one of the most powerful approaches currently used for calculating the properties of few-body systems. Despite its conceptual simplicity, the method offers great flexibility, high accuracy, and can be used to study diverse quantum systems, ranging from small atoms and molecules to light nuclei, hadrons, quantum dots, and Efimov systems. The basic theoretical foundations are discussed, recent advances in the applications of explicitly correlated Gaussians in physics and chemistry are reviewed, and the strengths and weaknesses of the explicitly correlated Gaussians approach are compared with other few-body techniques.

show abstract

“…Such materials have, for example, been used to investigate Anderson localization of light [1], line profiles of nano-confined positronium atom emission [2], random lasing [3], storage of hydrogen and carbon dioxide [4], and efficiency enhancements of solar cells [5,6]. However, determining the internal geometrical features, such as porosity and pore sizes, remains nontrivial.…”

Section: Introductionmentioning

confidence: 99%