Feshbach projection operator approach to positron annihilation

dc.creatorSanchez, SD
dc.creatorLima, MAP
dc.creatorVarella, MTD
dc.date2009
dc.dateNOV
dc.date2014-07-30T17:34:50Z
dc.date2015-11-26T16:42:01Z
dc.date2014-07-30T17:34:50Z
dc.date2015-11-26T16:42:01Z
dc.date.accessioned2018-03-28T23:26:25Z
dc.date.available2018-03-28T23:26:25Z
dc.identifierPhysical Review A. Amer Physical Soc, v. 80, n. 5, 2009.
dc.identifier1050-2947
dc.identifierWOS:000272310000091
dc.identifier10.1103/PhysRevA.80.052710
dc.identifierhttp://www.repositorio.unicamp.br/jspui/handle/REPOSIP/66884
dc.identifierhttp://repositorio.unicamp.br/jspui/handle/REPOSIP/66884
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/1273126
dc.descriptionConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.descriptionFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.descriptionWe present a theory of vibrationally enhanced positron annihilation on molecules based on the Feshbach projection operator formalism. A key aspect of the present approach is the fact that no direct vibrational excitation is assumed, i.e., the attachment mechanism is electronic in nature, arising from positron-electron correlation-polarization forces, and energy transfer to the nuclei essentially follows from the difference between the potential-energy surfaces of the isolated target and the positron-molecule compound; moreover, no a priori assumption is made on the character of the transient (bound or virtual state). An approximate relation between the annihilation parameter Z(eff) and the vibrationally summed cross section is presented, as well as a hierarchy of approximations that may allow for elaborate model calculations. We also discuss how important aspects of the annihilation process are taken into account in the present theory, such as isotope effects, vibrational energy redistribution and relative strengths among vibrational resonances. For completeness, semiempirical model calculations for acetylene and ethylene are presented. Despite the stringent approximations employed in this simplest version of the theory, fair agreement with experimental data was obtained in the vicinity of 0 -> 1 thresholds.
dc.description80
dc.description5
dc.descriptionConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.descriptionFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.descriptionConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.descriptionFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.languageen
dc.publisherAmer Physical Soc
dc.publisherCollege Pk
dc.publisherEUA
dc.relationPhysical Review A
dc.relationPhys. Rev. A
dc.rightsaberto
dc.rightshttp://publish.aps.org/authors/transfer-of-copyright-agreement
dc.sourceWeb of Science
dc.subjectorganic compounds
dc.subjectpositron annihilation
dc.subjectpotential energy surfaces
dc.subjectresonant states
dc.subjectvibrational states
dc.subjectElectron-molecule-scattering
dc.subjectVibrational-excitation
dc.subjectCross-sections
dc.subjectTdscf Approximation
dc.subjectNuclear Reactions
dc.subjectReaction Surface
dc.subjectUnified Theory
dc.subjectDynamics
dc.subjectImpact
dc.subjectModel
dc.titleFeshbach projection operator approach to positron annihilation
dc.typeArtículos de revistas


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