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Systematic Measurements of Doppler-Coincidence Spectra for Positron Annihilation in Pure Metals and Semiconductors

100%

Deng W., Pliszka D., Brusa R., Karwasz G., Zecca A.

Acta Physica Polonica A

2002

vol. 101

issue 6

875-892

Doppler-broadening measurements of the electron-positron annihilation line in twenty six elements are presented. The adopted coincidence technique allows to reduce the background and point out the contribution of positron annihilation with core electrons. The changes of the high momentum contribution is presented for selected examples and a semiempirical analysis of the dependence on electronic structure is performed. Measured data are in a good agreement with recent theoretical calculations and can be used to identification of impurities surrounding open volume defects.

Surfaces of Electron-Emitting Glasses Studied by a Slow Positron Beam

73%

Pliszka D., Gazda M., Kusz B., Trzebiatowski K., Karwasz G., Deng W., Brusa R., Zecca A.

Acta Physica Polonica A

2001

vol. 99

issue 3-4

465-472

Semi-conducting glasses used for electron multipliers and microchannel plate devices are obtained by surface modification of Pb or Bi-reach silicon-based glasses. The reduced layer extends down to 200-500 nm, much more than the effective depth of the electron-emitting layer. By the use of slow-positron beam we monitor the structural changes undergoing in near-to-surface layers after isothermal annealing. The measurements suggest a possible correlation between secondary-electron emission coefficient and the Doppler-broadening S-parameter. On these samples there were also performed atomic force microscopy, secondary electron emission, differential scanning calorimetry, and electric conductivity measurements.

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2 Acta Physica Polonica A

1 2002

1 2001

2 Brusa R.

2 Deng W.

2 Karwasz G.

2 Pliszka D.

2 Zecca A.

1 Gazda M.

1 Kusz B.

1 Trzebiatowski K.

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Systematic Measurements of Doppler-Coincidence Spectra for Positron Annihilation in Pure Metals and Semiconductors

Surfaces of Electron-Emitting Glasses Studied by a Slow Positron Beam