Positronium formation cross-sections in the ground and excited states ( $\mathsf{n=2}$ levels) in an $\mathsf{e^{+}}$ -He atom collision

1999 ◽  
Vol 6 (3) ◽  
pp. 295-302 ◽  
Author(s):  
B. Nath ◽  
C. Sinha
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Positronium Formation ◽  
He Atom ◽  
Atom Collision

Excited states of positronium in positron–hydrogen charge exchange

1978 ◽  
Vol 56 (5) ◽  
pp. 565-570 ◽  
Author(s):  
V. S. Kulhar ◽  
C. S. Shastry
Keyword(s):  
Excited States ◽  
Charge Exchange ◽  
Cross Sections ◽  
Ground State ◽  
Born Approximation ◽  
Energy Region ◽  
Hydrogen Charge ◽  
Positronium Formation ◽  
State Approximation ◽  
Higher Excited States

The two state approximation method for the study of the rearrangement collisions is applied to the process of positronium formation in excited states for positron–hydrogen charge exchange collisions. Differential and integrated cross sections are computed for positronium formation in 2S, 2P, and 3S excited states. The results obtained in the energy region 2 to 10 Ry are compared with positronium formation cross sections in ground state. Total positronium formation cross sections including the contributions of capture into all the higher excited states of positronium are also computed in the first Born approximation and the two state approximation in the energy region considered.

EXCITATION AND IONIZATION CROSS SECTIONS FOR HE I FROM NORMALIZED BORN AND K-MATRIX CALCULATIONS: ΔS = 0 TRANSITIONS FROM n = 2, 3 EXCITED STATES

2000 ◽  
Vol 74 (1) ◽  
pp. 123-153 ◽  
Author(s):  
I.L. Beigman ◽  
L.A. Vainshtein ◽  
M. Brix ◽  
A. Pospieszczyk ◽  
I. Bray ◽  
...  
Keyword(s):  
Excited States ◽  
Cross Sections ◽  
Ionization Cross ◽  
Ionization Cross Sections ◽  
K Matrix

Multiple ionization of argon by positron impact

1996 ◽  
Vol 74 (7-8) ◽  
pp. 373-375 ◽  
Author(s):  
R. Hippler ◽  
S. Helms ◽  
U. Brinkmann ◽  
J. Deiwiks ◽  
H. Schneider ◽  
...  
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Experimental Results ◽  
Positronium Formation ◽  
Positron Impact ◽  
Single Ionization ◽  
Multiple Ionization

Recent experimental results for the multiple ionization of argon by positron impact have been reanalysed. Absolute cross sections for the double and triple ionization of argon were obtained from measured ratios of double-to-single and triple-to-single ionization, using known cross sections for single ionization and for positronium formation. Distinct differences compared to similar results for electron impact are noted.

Possible narrow and deep minima in the photoionization cross sections of excited states

1987 ◽  
Vol 36 (5) ◽  
pp. 2108-2111 ◽  
Author(s):  
I. B. Goldberg ◽  
R. H. Pratt
Keyword(s):  
Excited States ◽  
Cross Sections

Evidence of the Participation of Electronic Excited States in the Mechanism of Positronium Formation in Substitutional Tb1-xEux(dpm)3 Solid Solutions Studied by Optical and Positron Annihilation Spectroscopies

2012 ◽  
Vol 733 ◽  
pp. 245-248 ◽  
Author(s):  
Welington F. Magalhães ◽  
Fernando Fulgêncio ◽  
Fernando C. de Oliveira ◽  
Dario Windmöller ◽  
José C. Machado ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Excited States ◽  
Solid Solutions ◽  
Electronic States ◽  
Positronium Formation ◽  
Metal Charge ◽  
Positron Annihilation Lifetime ◽  
Electronic Excited States ◽  
Relevant Role ◽  
Metal Charge Transfer

Positron annihilation lifetime (PALS) and photoluminescence spectroscopies measurements were performed in Tb(III) and Eu(III) dipivaloylmethanates, Tb(dpm)3and Eu(dpm)3, and also on their binary solid solutions of general formula Tb1-xEux(dpm)3. A correlation between the5D4Tb(III) energy level lifetime and the positronium formation probability was observed, indicating that the ligand-to-metal charge transfer LMCT states act in both luminescence quenching and positronium formation inhibition. From these results, a new model is proposed, showing that excited electronic states have a relevant role in the positronium formation mechanism.

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