scholarly journals The quantal calculation of the photo-ionization cross-section of atomic potassium

1947 ◽  
Vol 188 (1014) ◽  
pp. 350-357 ◽  
Keyword(s):  
Cross Section ◽  
Ionization Cross Section ◽  
Great Sensitivity ◽  
Wave Functions ◽  
Laboratory Measurement ◽  
Frequency Curve ◽  
Ionization Cross ◽  
The Cross ◽  
Photo Ionization

The photo-ionization of atomic potassium is investigated using quantal methods. Emphasis is laid on the great sensitivity of the cross-section to the wave functions employed. The general features of the cross-section as revealed by the laboratory measurement can be understood. To explain the finite minimum observed in the cross-section-frequency curve it is necessary to take into account non-separability effects.

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.

The photo-ionization cross-section of neon

1953 ◽  
Vol 220 (1140) ◽  
pp. 71-76 ◽  
Keyword(s):  
Cross Section ◽  
Ionization Cross Section ◽  
Wave Length ◽  
Grazing Incidence ◽  
Absorption Coefficients ◽  
Ionization Cross ◽  
Ionization Limit ◽  
Resonance Transitions ◽  
Photo Ionization ◽  
Dipole Length

The absorption of radiation of wave-length between 230 and 800 Å in neon was measured photometrically in a grazing incidence vacuum spectrograph. For wave-lengths longer than that corresponding to the first ionization limit the absorption coefficients were found to be zero except for photo-excitation of resonance transitions. Two sharp absorption edges were observed at 575 and 256 Å corresponding to the L 3 - and L 1 -edges respectively with a flat maximum between them. The photo-ionization cross-section at the first ionization limit was found to be 5⋅4 x 10 -18 cm 2 independent of the pressure between 50 and 500 μ ; this should be compared with the theoretical value of 5⋅8 x 10 -18 cm 2 obtained by Seaton using a dipole-length approximation. Between 575 and 400 Å the calculated and experimental curves agreed closely within the limits of measurement.

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