Angular Momentum Transfer in the Theory of Angular Distributions

Fano, U.; Dill, Dan

doi:10.1103/physreva.6.185

Cited by 362 publications

(101 citation statements)

References 8 publications

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“…In this case,, j, is free to take on values other than l,, which can lead to additional terms in the expression for P(&). Consideration of this very important aspect of the photoionization process is at the heart of the so-called angular-momentumtransfer formulation by Dill and co-workers [31,32,34,36,39,431. Other formulations of equivalent detail exist (e.g., ref.…”

Section: Anisotropic Final-state Interactions Inmentioning

confidence: 99%

“…This general result is now commonly written in the form where a is the integrated cross-section, and 8 is the photoelectron's direction relative to the electric vector of linearly polarized light, in order to focus the study of photoelectron angular distributions on a single parameter, P, the so-called asymmetry parameter. Theoretical expressions for for both atoms [30-361 and molecules [31,32,[37][38][39][40][41] began appearing just as modern measurements using VUV and soft X-ray light sources were producing accurate results. The work of Cooper and Zare [30] which expressed fl for atoms in an independent electron, LS-coupled scheme has had a great impact on the work described below, because it represents an easily applicable and realistic level of sophistication and because it emerged at a time when practical methods to compute one-electron photoionization cross-sections for atoms had just begun to be exploited extensively (see e.g.…”

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Angular Distributions of Photoelectrons and Non-Thermal Photoions From Atoms and Molecules

Dehmer

1978

J. Phys. Colloques

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RCsumC. -Durant ces dix dernikres annees, les distributions angulaires des photo-electrons ont kte exclusivement utilisees pour ktudier la dynamique des processus de photoionisation dans les atomes et les molkcules. Nous faisons le point, ici, sur les resultats les plus marquants survenus depuis la dernikre Conference Internationale d'il y a trois ans. De loin, les plus grands progres ont eu lieu pour les atomes, l'interst s'etant plus particulierement port6 sur les points suivants : amelioration de l'ordre zero (Hartree-Slater, Cooper-Zare), comprehension du paramttre d'asymetrie P(&), en considerant les correlations Clectroniques, les effets relativistes, les interactions de 1'Ctat final anisotropique. L'etude des gaz rares a bkneficik de l'ttroite coordination entre l'expkrience et la theorie, tandis que l'etude des atomes non spheriques est restee principalement theorique, mis a part les mesures rkcentes sur I'oxygkne atomique. Les etudes de distribution angulaire sur les molecules sont encore a un stade t r b preliminaire de dtveloppement. Ceci resulte du manque de mesures en fonction de la longueur d'onde, mises a part les experiences trks recentes, et l'absence de methodes theoriques pratiques et realistes. Le point sera donc fait sur ce travail recent, ainsi que sur une selection de travaux plus anciens concernant les molCcules et obtenus avec des raies de resonance. De plus, une nouvelle serie d'ktudes angulaires sur les molCcules -la distribution angulaire des ions non thermiques formes par photoionisation dissociative -fournissant des informations complCmentaires sur les mesures correspondantes avec des photoClectrons, sera presentee.Abstract. -During the last ten years, photoelectron angular distributions have been used extensively to study the dynamics of the photoionization process in atoms and molecules. Here we review some major advances in this body of work, with special emphasis on results emerging since the last Conference on VUV Radiation Physics three years ago. By far the greatest progress has occurred for atoms, where interest is focussed on improving our zero-order (Hartree-Slater, Cooper-Zare) understanding of the asymmetry parameter P(&), by considering electron correlations, relativistic effects, and anisotropic final-state interactions. The study of the rare gases has benefitted from extensive coordination between experiment and theory, whereas work on non-spherical atoms has been mainly theoretical, with the only measurements being performed very recently on atomic oxygen. Angular distribution studies on molecules are in a much earlier stage of development. Progress has been impeded by the lack of practical, realistic theoretical methods and wavelength-dependent measurements, both of which are becoming available only now. This recent work, together with selected topics from earlier resonance-line work on molecules will be reviewed. In addition, a new class of angle-dependent stud~es of molecules will be discussed -the angular distribution of non-thermal ions formed by dissociative ph...

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Section: Anisotropic Final-state Interactions Inmentioning

confidence: 99%

mentioning

confidence: 99%

Angular Distributions of Photoelectrons and Non-Thermal Photoions From Atoms and Molecules

Dehmer

1978

J. Phys. Colloques

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“…Here we develop theoretical expressions for the photoelectron angular distributions of N 2 based on the MQDT framework of Dill and Fano 34,35 and as implemented by Raoult et al 26 for the photoionization of molecular hydrogen. The application to N 2 is straightforward due to the happy coincidence that the ground state neutral and ion have the same symmetry as in H 2 , i.e., 1 Σ g + and 2 Σ g + symmetry, respectively, and thus single-photon ionization near threshold leads to the ejection of an odd-photoelectron.…”

Section: Theoretical Angular Distribution Parametersmentioning

confidence: 99%

“…In particular, as shown in Sec. III, we can predict the photoelectron angular distributions for a variety of rotationally resolved autoionizing resonances in N 2 by using a simplification of the multichannel quantum defect theory (MQDT) machinery 26,34,35 originally developed for H 2 . The predictions are in reasonable agreement with the present experimental results and provide insight into the assignments of the autoionizing resonances as well as into the corresponding decay mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Photoelectron angular distributions from rotationally resolved autoionizing states of N2

Chartrand

McCormack

Jacovella

et al. 2017

The Journal of Chemical Physics

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The single-photon, photoelectron-photoion coincidence spectrum of N 2 has been recorded at high (∼1.5 cm 1 ) resolution in the region between the N 2 + X 2 Σ g + , v + = 0 and 1 ionization thresholds by using a double-imaging spectrometer and intense vacuum-ultraviolet light from the Synchrotron SOLEIL. This approach provides the relative photoionization cross section, the photoelectron energy distribution, and the photoelectron angular distribution as a function of photon energy. The region of interest contains autoionizing valence states, vibrationally autoionizing Rydberg states converging to vibrationally excited levels of the N 2 + X 2 Σ g + ground state, and electronically autoionizing states converging to the N 2 + A 2 Π and B 2 Σ u + states. The wavelength resolution is sufficient to resolve rotational structure in the autoionizing states, but the electron energy resolution is insufficient to resolve rotational structure in the photoion spectrum. A simplified approach based on multichannel quantum defect theory is used to predict the photoelectron angular distribution parameters, β, and the results are in reasonably good agreement with experiment. Published by AIP Publishing.

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“…1). The angular distribution for photoexcitation, f (θ), about the polarization of the exciting radiation (e-vector) (for a one-photon excitation in the dipole-approximation) is given by [7]:…”

Section: Functions For Electron-peak Profilesmentioning

confidence: 99%

Core excitation in O3 localized to one of two symmetry-equivalent chemical bonds: Molecular alignment through vibronic coupling

Wiesner

Brito

Sorensen

et al. 2005

The Journal of Chemical Physics

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Core excitation from terminal oxygen OT in O3 is shown to be an excitation from a localized core orbital to a localized valence orbital. The valence orbital is localized to one of the two equivalent chemical bonds. We experimentally demonstrate this with the Auger Doppler effect which is observable when O3 is core-excited to the highly dissociative OT 1s −1 7a 1 1 state. Auger electrons emitted from the atomic oxygen fragment carry information about the molecular orientation relative to the electromagnetic field vector at the moment of excitation. The data together with analytical functions for the electron-peak profiles give clear evidence that the preferred molecular orientation for excitation only depends on the orientation of one bond, not on the total molecular orientation. The localization of the valence orbital "7a1" is caused by mixing of the valence orbital "5b2" through vibronic coupling of anti-symmetric stretching mode with b2-symmetry. To the best of our knowledge, it is the first discussion of the localization of a core excitation of O3. This result explains the success of the widely used assumption of localized core excitation in adsorbates and large molecules.

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Angular Momentum Transfer in the Theory of Angular Distributions

Cited by 362 publications

References 8 publications

Angular Distributions of Photoelectrons and Non-Thermal Photoions From Atoms and Molecules

Angular Distributions of Photoelectrons and Non-Thermal Photoions From Atoms and Molecules

Photoelectron angular distributions from rotationally resolved autoionizing states of N2

Core excitation in O3 localized to one of two symmetry-equivalent chemical bonds: Molecular alignment through vibronic coupling

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