scholarly journals Laser Assisted Electron - Alkali Atom Collisions

1996 ◽  
Vol 49 (6) ◽  
pp. 1109 ◽  
Author(s):  
Vinod Prasad ◽  
Rinku Sharma ◽  
Man Mohan
Keyword(s):  
Cross Section ◽  
Born Approximation ◽  
Laser Intensity ◽  
Alkali Atom ◽  
Incident Electron Energy ◽  
Excitation Process ◽  
Alkali Atoms ◽  
Atom Interaction ◽  
Electron Photon ◽  
Atomic States

Lasar assisted inelastic scattering of electrons by alkali atoms is studied theoretically. The non-perturbative quasi-energy method, which is generalised for many atomic states, is used to describe the laser–atom interaction, and the electron–atom interaction is treated within the first Born approximation. We have calculated the total cross section for the excitation of sodium atoms due to simultaneous electron–photon collisions. We show the effect of laser and collision parameters, e.g. laser intensity, polarisation and incident electron energy, on the excitation process.

A measurement of the cross-section for detachment of electrons from H – by electron impact

1967 ◽  
Vol 299 (1459) ◽  
pp. 525-537 ◽  
Keyword(s):  
Cross Section ◽  
Born Approximation ◽  
Theoretical Calculations ◽  
Functional Dependence ◽  
Incident Electron ◽  
Incident Electron Energy ◽  
Measured Cross Section ◽  
Neutral Particles ◽  
Beam Method ◽  
The Cross

A crossed beam method has been used to measure the cross-section for the production of neutral particles in single collisions of electrons with H - ions at incident electron energies from 9 to 500 eV. The measured cross-section reaches a maximum of 50 Å 2 at an energy of 14 eV, and may be represented by the function Q = (1-1.6/( E log 10 E ) ½ )950/ E log 10 E /0·92, where the cross-section Q is in units of Å 2 and the incident electron energy E in units of electronvolts. The magnitude and functional dependence of the cross-section agree well with theoretical calculations based on the Bethe-Born approximation at energies above 20 eV.

Elastic scattering of intermediate-energy positrons and electrons by alkali atoms

1982 ◽  
Vol 60 (4) ◽  
pp. 601-604 ◽  
Author(s):  
J. M. Wadehra
Keyword(s):  
Wave Function ◽  
Elastic Scattering ◽  
Cross Section ◽  
Born Approximation ◽  
Intermediate Energy ◽  
Target Atom ◽  
Slater Type ◽  
Hartree Fock ◽  
Static Interaction ◽  
Alkali Atoms

In this paper we present the total elastic scattering cross section for collisions of intermediate energy (500–1000 eV) positrons and electrons by alkali atoms (Li, Na, K, Rb). Calculations are done by using the first Born approximation with polarization plus static interaction. The static interaction is obtained by using a Hartree–Fock–Slater type wave function for the target atom and the polarization interaction is modeled by using a pseudopotential.

The use of an energy-filtering electron microscope to reduce chromatic aberration in images of thick biological specimens

1986 ◽  
Vol 44 ◽  
pp. 88-91
Author(s):  
L. D. Peachey ◽  
J. P. Heath ◽  
G. Lamprecht
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Cross Section ◽  
Electron Scattering ◽  
Chromatic Aberration ◽  
Image Resolution ◽  
Incident Electron Energy ◽  
Energy Filtering ◽  
Transmission Electron

Biological specimens of cells and tissues generally are considerably thicker than ideal for high resolution transmission electron microscopy. Actual image resolution achieved is limited by chromatic aberration in the image forming electron lenses combined with significant energy loss in the electron beam due to inelastic scattering in the specimen. Increased accelerating voltages (HVEM, IVEM) have been used to reduce the adverse effects of chromatic aberration by decreasing the electron scattering cross-section of the elements in the specimen and by increasing the incident electron energy.

The influence of the nuclear and atomic form factors on the muon bremsstrahlung cross section

1968 ◽  
Vol 46 (10) ◽  
pp. S377-S380 ◽  
Author(s):  
A. A. Petrukhin ◽  
V. V. Shestakov
Keyword(s):  
Form Factor ◽  
Cross Section ◽  
Born Approximation ◽  
Form Factors ◽  
Experimental Results ◽  
Simple Analytical Expression ◽  
Nuclear Form Factor ◽  
The Cross ◽  
Atomic Electrons ◽  
Bremsstrahlung Process

The cross section for the muon bremsstrahlung process is calculated as a function of the nuclear form factor in the Born approximation following the Bethe and Heitler theory. The influence of the nuclear form factor is greater than that taken by Christy and Kusaka. The simple analytical expression for the effect of the screening of the atomic electrons is found. The influence of a decrease in the cross section upon the interpretation of some experimental results is estimated.

Rearrangement collisions: two-particle exchange

1964 ◽  
Vol 277 (1369) ◽  
pp. 206-213 ◽  
Keyword(s):  
Energy Dependence ◽  
Cross Section ◽  
Born Approximation ◽  
High Energy ◽  
Electron Exchange ◽  
Final States ◽  
Particle Exchange ◽  
Exchange Cross Section

It is shown that the first Bom approximation for the exchange of two uncorrelated electrons should vanish. A formalism for the T matrix is presented which has this property. The high-energy result for the two-electron exchange cross-section previously calculated in first Born approximation behaves like E -7 . This result is in error due to a lack of orthogonality of initial and final states. When this is corrected the result for uncorrelated electrons has an energy dependence E -11 . The introduction of correlation gives terms behaving like E -10 which cannot be calculated unam biguously.

A measurement of the ionization cross-section of Ne + to Ne 2+ by electron impact

1963 ◽  
Vol 274 (1359) ◽  
pp. 546-551 ◽  
Keyword(s):  
Electron Energy ◽  
Cross Section ◽  
Ionization Cross Section ◽  
Incident Electron Energy ◽  
Ionization Cross ◽  
Maximum Value ◽  
Beam Method ◽  
The Cross ◽  
Semi Empirical ◽  
Limits Of Error

The crossed-beam method described by the authors in 1961 was used to measure the cross-section of Ne + in the reaction Ne + + e → Ne 2+ + 2 e . The cross-section increases linearly with electron energy near the threshold and attains a maximum value of 3·13 x 10 -17 cm 2 at 200 eV. The errors in the measurements were estimated to be less than ± 10% and the highest incident electron energy used was 1000 eV. A semi-empirical formula proposed by Drawin in 1961 describes the measured cross-section within the above limits of error when the two adjustable parameters take the values ξf 1 = 5·25 and f 2 = 0·70.

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