Dependence of positron–molecule binding energies on molecular properties

Danielson, J. R.; Young, Jason A.; Surko, C. M.

doi:10.1088/0953-4075/42/23/235203

Cited by 85 publications

(101 citation statements)

References 40 publications

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“…Examples of published binding energy measurements are shown in Fig. 1 as a function of the dipole polarizability α [12], along with calculated binding energies for several atoms [6]. These b values resulted in the development of an arguably crude, but useful, phenomenological description of b in terms of the molecular * csurko@ucsd.edu dipole polarizability α and the permanent dipole moment of the molecule μ [12], b = 12.4 (α + 1.6μ − 5.6) (meV), (1) where α is in units of 10 −24 cm 3 and μ is in debyes.…”

Section: Introductionmentioning

confidence: 99%

Interplay between permanent dipole moments and polarizability in positron-molecule binding

et al. 2012

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Energy-resolved studies of positron-molecule collisions exhibit vibrational Feshbach resonances in annihilation, thus providing evidence that positrons can bind to these species. The downshifts of the observed resonances from the positions of the vibrational modes provides a measure of the positron-molecule binding energies, which range from 1 to 300 meV. Reported here are annihilation spectra and binding energies for a wider range of chemical species than studied previously, including aldehydes, ketones, formates, acetates, and nitriles. While the measured binding energies show an approximate correlation with molecular dipole polarizability and permanent dipole moment, other effects are important for dipole moments 2.0 D. For these compounds, it appears that localization of the positron wave function near a portion of the molecule leads to enhanced binding and an increased dependence on both the molecular dipole moment and the electron-positron correlations. The relationship of these results to theoretical calculations is discussed.

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Section: Introductionmentioning

confidence: 99%

Interplay between permanent dipole moments and polarizability in positron-molecule binding

et al. 2012

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“…Observation of resonances thus allows one to measure ε b . At present, positron binding energies for about 30 molecules have been determined in this way [10].…”

Section: Introductionmentioning

confidence: 99%

Resonant positron annihilation in ammonia

Gribakin

2010

J. Phys.: Conf. Ser.

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Abstract. Positron annihilation in ammonia is analyzed using the framework of resonant annihilation [G. F. Gribakin and C. M. R. Lee, Phys. Rev. Lett. 97, 193201 (2006)]. In particular, we show that molecular rotations can have a measurable effect on the annihilation rates at room temperatures. Rotation leads to broadening of vibrational Feshbach resonances. Rotations also allow a distinct contribution at low positron energies in the form of a rotational Feshbach resonance. This resonance can enhance the annihilation rate for thermalized roomtemperature positrons. Comparison of theory and experiment shows that overtone and combination vibrations, including those due to inversion doubling, likely play an important role.

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“…A comparison of the measured cross section with the theoretical results derived in this paper should provide an estimate of the positron binding energy, which could be compared with existing high-quality predictions [12][13][14]. It would also be interesting to apply this method to molecules for which the binding energies are known from the resonant annihilation studies [15,[19][20][21][22]. Unlike positron-molecule annihilation which probes resonant, quasibound states, the molecular analog of reaction (2) should lead to population of the true positron-molecule bound states.…”

Section: Introductionmentioning

confidence: 91%

“…The downshift of a resonance relative to the vibrational excitation energy provided a measure of * aswann02@qub.ac.uk † d.cassidy@ucl.ac.uk ‡ a.deller@ucl.ac.uk § g.gribakin@qub.ac.uk the positron binding energy. This has enabled positron binding energies to be determined for over seventy molecules [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Formation of positron-atom bound states in collisions between Rydberg Ps and neutral atoms

Swann¹,

Cassidy

Deller

et al. 2016

Phys. Rev. A

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Predicted twenty years ago, positron binding to neutral atoms has not yet been observed experimentally. A new scheme is proposed to detect positron-atom bound states by colliding Rydberg positronium (Ps) with neutral atoms. Estimates of the charge-transfer reaction cross section are obtained using the first Born approximation for a selection of neutral atom targets and a wide range of incident Ps energies and principal quantum numbers. We also estimate the corresponding Ps ionization cross section. The accuracy of the calculations is tested by comparison with earlier predictions for Ps charge transfer in collisions with hydrogen and antihydrogen. We describe an existing Rydberg Ps beam suitable for producing positron-atom bound states and estimate signal rates based on the calculated cross sections and realistic experimental parameters. We conclude that the proposed methodology is capable of producing such states and of testing theoretical predictions of their binding energies.

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Dependence of positron–molecule binding energies on molecular properties

Cited by 85 publications

References 40 publications

Interplay between permanent dipole moments and polarizability in positron-molecule binding

Interplay between permanent dipole moments and polarizability in positron-molecule binding

Resonant positron annihilation in ammonia

Formation of positron-atom bound states in collisions between Rydberg Ps and neutral atoms

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