Selective observation of continuum transitions in the Pb+Pb quasimolecule

Vincent, P.; Bokemeyer, H.; Emling, H.; Greenberg, Jay; Grosse, E.; Schwalm, D.

doi:10.1007/bf01415133

Cited by 5 publications

(6 citation statements)

References 19 publications

(33 reference statements)

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“…The experimental value, however, is 0.285±0.015 (Vincent and Greenberg, 1979). Other dynamic theories give a = \ (Muller, 1975) …”

Section: The Dynamic Theory Of Macek and Briggs Predicts That H Shomentioning

confidence: 89%

“…The x-ray energy E x need not be exactly the MO transition energy: any energy excess or deficit can be obtained by converting translational kinetic energy into electromagnetic energy. Weisskopf (1933) showed that the line shape for the transition i-*/ can "be calculated from the Fourier transform of the dipole velocity matrix element…”

Section: Separation Of One-and Two-collision Mo X-ray Emissionmentioning

confidence: 99%

“…Coincidences in Pb -f Pb collisions have been measured by Vincent et al (1985). Due to the strong 2p\-2p\ spin-orbit splitting in Pb + Pb quasimolecules, coupling between the a and ir or p\ and p\ MO's is small, hence one can in principle measure just 2p\->\s\ transitions [^n7r=l an d #2^=0 in Eq.…”

Section: Molecular-orbital X-ray Separated-atom K X-ray Coincidencesmentioning

confidence: 99%

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X rays from quasimolecules

Anholt

1985

Rev. Mod. Phys.

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In slow heavy-ion-atom collisions, inner-shell electrons with velocities larger than the projectile velocity form diatomic molecular orbitals around the projectile and target nuclei. If a vacancy exists in one of these orbitals, it can decay at some point during collision, emitting an x ray characteristic of the molecular transition energy at that internuclear distance. Since the projectile-target internuclear distance varies during the collision, x-ray continua are seen, which for \so molecular-orbital x rays (transitions to vacancies in the lowest Iscr orbital) stretch toward the united-atom AT-shell binding energy. This paper reviews the theory of and the experimental evidence for molecular-orbital x-ray emission. A historical overview of the development of these studies is given, showing how the theory of quasimolecular x-ray emission has evolved from a semiclassical quasistatic model to a general dynamic theory, including the Coriolis coupling between molecular orbitals making up the initial and final states. X-ray cross section, angular distribution, and other measurements are discussed, and their impact on the development of the theory of molecularorbital x-ray emission is illustrated.

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“…The experimental value, however, is 0.285±0.015 (Vincent and Greenberg, 1979). Other dynamic theories give a = \ (Muller, 1975) …”

Section: The Dynamic Theory Of Macek and Briggs Predicts That H Shomentioning

confidence: 89%

Section: Separation Of One-and Two-collision Mo X-ray Emissionmentioning

confidence: 99%

Section: Molecular-orbital X-ray Separated-atom K X-ray Coincidencesmentioning

confidence: 99%

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X rays from quasimolecules

Anholt

1985

Rev. Mod. Phys.

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“…are given by the Coriolis-coupling equations [5], subject to the initial conditions an, (-oe) = az,(t ) = 1 and as~ (-co)=an, (-oe)=0. (2) Previous calculations of MO x-ray production [3,4] do not give the selective MO x-ray intensities, because the ultimate fate of the vacancy after the MO x-ray transition is not considered. Ford et al [6] and Kirsch et al [7] have suggested a method of calculating coincident MO x-ray cross sections.…”

mentioning

confidence: 99%

“…The K-coincident MO x-rays are emitted with a much larger anisotropy than the non-coincident MO x-rays.Recently, measurements of lsa molecular orbital (MO) x-rays in coincidence with K x-rays emitted after the collision by the projectile and target atoms have been made [1,2]. Since the 2pa MO correlates to the separated-atom (SA)K levels in a symmetric collision, these coincidence experiments allow, in principle, for a selective observation of MO x-rays.…”

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confidence: 99%

Calculations of molecular-orbital ? separated-atom x-ray coincidences

Anholt

1983

Z Physik A

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The calculated cross section for the production of i s a molecular orbital (MO) x-rays in coincidence with projectile and target K x-rays is a factor of 0.2 to 0.3 smaller than the non-coincident cross section. The K-coincident MO x-rays are emitted with a much larger anisotropy than the non-coincident MO x-rays.Recently, measurements of lsa molecular orbital (MO) x-rays in coincidence with K x-rays emitted after the collision by the projectile and target atoms have been made [1,2]. Since the 2pa MO correlates to the separated-atom (SA)K levels in a symmetric collision, these coincidence experiments allow, in principle, for a selective observation of MO x-rays. Only electronic transitions from the 2pa to the 1 sa MO that leave the vacancy in the 2po-MO are observed. However, this simple picture is complicated by the very strong Coriolis coupling between the 2 p a and 2pn MO's which occurs for collision systems with combined charge (100 [3,4]. Instead of a pure 2pa, one has two linear combinations of 2pa and 2pn x MO's that can be written aswhere az~ and az. are given by the Coriolis-coupling equations [5], subject to the initial conditions an, (-oe) = az,(t ) = 1 and as~ (-co)=an, (-oe)=0.(2) Previous calculations of MO x-ray production [3,4] do not give the selective MO x-ray intensities, because the ultimate fate of the vacancy after the MO x-ray transition is not considered. Ford et al. [6] and Kirsch et al. [7] have suggested a method of calculating coincident MO x-ray cross sections. It is possible to understand their formulations simply if we consider just three levels, the lsa, 2pZ, and 2pn x MO's, occupied by just two electrons of identical spin. We neglect the lly and all other orbitals which cannot couple to the 2pa where r 1 and r 2 are the coordinates for electron 1 and 2. Using first-order perturbation theory, we obtain for the total wavefunction at the end of the collision (t = oe)where C O ~ 1,and C 2 is given by a similar equation. In (5), H' is the radiative perturbation matrix element; thus C 1 is identical to the amplitude Cz for the 2p S electron to radiate a MO x-ray, as given by Anholt [3]. At

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