scholarly journals Nachlieferung von Elektronen beim Entladungsaufbau in Wasserstoff und Sauerstoff für E/p von 60 bis 3000 Volt/cm Torr

1967 ◽  
Vol 22 (3) ◽  
pp. 347-354
Author(s):  
H. Schlumbohm
Keyword(s):  
Excited States ◽  
Charge Exchange ◽  
Electronic States ◽  
Single Electron ◽  
Secondary Electrons ◽  
Electron Collisions ◽  
Positive Ions ◽  
Additional Process ◽  
Electron Avalanches ◽  
Ion Species

By analysing the temporal current shapes of electron avalanches the different secondary ionisation processes occuring in H2- and O2-discharges have been separated and data taken. In hydrogen at E/p < 250 volts/cm Torr secondary electrons are released at the cathode by photons emitted mainly from excited states of the WERNER-bands of the H2-molecule. In oxygen secondary electrons are released both within the gas and at the cathode at E/p < 500 volts/cm Torr by photons from electronic states above the first ionisation level of the O2-molecule, which are excited by single electron collisions.With increasing E/p additional secondary electrons in hydrogen are produced by positive ions at the cathode, but for E/p > 170 volts/cm Torr the avalanche currents cannot be interpreted by the photon and ion processes thus indicating the action of a third mechanism. The same result was obtained for oxygen at E/p > several 100 volts/cm Torr. This additional process is discussed on the basis of different ion species and a possible action of fast neutral molecules resulting from charge exchange collisions.

Excited-Atom Production by Electron Bombardment of Alkali-Halides

1986 ◽  
Vol 75 ◽  
Author(s):  
R. E. Walkup ◽  
Ph. Avouris ◽  
A. P. Ghosh
Keyword(s):  
Gas Phase ◽  
Excited States ◽  
Ground State ◽  
Excited Atom ◽  
Alkali Halides ◽  
Electron Bombardment ◽  
Secondary Electrons ◽  
Excited Atoms ◽  
Positive Ions ◽  
Electronically Excited

AbstractWe present experimental results which suggest a new mechanism for the production of excited atoms and ions by electron bombardment of alkali-halides. Doppler shift measurements show that the electronically excited atoms have a thermal velocity distribution in equilibrium with the surface temperature. Measurements of the absolute yield of excited atoms, the distribution of population among the excited states, and the dependence of yield on incident electron current support a model in which excited atoms are produced by gas-phase collisions between desorbed ground-state atoms and secondary electrons. Similarly, gas-phase ionization of ground-state neutrals by secondary electrons accounts for a substantial portion of the positive ions produced by electron bombardment of alkali-halides.

Collection and counting efficiency

2017 ◽  
Author(s):  
A. G. Wright
Keyword(s):  
Quantum Efficiency ◽  
Standard Method ◽  
Shot Noise ◽  
Count Rate ◽  
Detection Efficiency ◽  
Collection Efficiency ◽  
Counting Efficiency ◽  
Single Electron ◽  
Anode Current ◽  
Secondary Electrons

Standards laboratories can provide a photocathode calibration for quantum efficiency, as a function of wavelength, but their measurements are performed with the photomultiplier operating as a photodiode. Each photoelectron released makes a contribution to the photocathode current but, if it is lost or fails to create secondary electrons at d1, it makes no contribution to anode current. This is the basis of collection efficiency, F. The anode detection efficiency, ε‎, allied to F, refers to the counting efficiency of output pulses. The standard method for determining F involves photocurrent, anode current, count rate, and the use of highly attenuating filters; F may also be measured using methods based on single-electron responses (SERs), shot noise, or the SER at the first dynode.

Effects of Space Charge on ESEM Gas Amplification

1997 ◽  
Vol 3 (S2) ◽  
pp. 609-610 ◽  
Author(s):  
B.L. Thiel ◽  
M.R. Hussein-Ismail ◽  
A.M. Donald
Keyword(s):  
Electric Field ◽  
Electrostatic Field ◽  
Secondary Electron ◽  
Sample Surface ◽  
Cascade Process ◽  
Secondary Electrons ◽  
Positive Ions ◽  
Space Charges ◽  
Cascade Amplification ◽  
Environmental Sem

We have performed a theoretical investigation of the effects of space charges in the Environmental SEM (ESEM). The ElectroScan ESEM uses an electrostatic field to cause gas cascade amplification of secondary electron signals. Previous theoretical descriptions of the gas cascade process in the ESEM have assumed that distortion of the electric field due to space charges can be neglected. This assumption has now been tested and shown to be valid.In the ElectroScan ESEM, a positively biased detector is located above the sample, creating an electric field on the order of 105 V/m between the detector and sample surface. Secondary electrons leaving the sample are cascaded though the gas, amplifying the signal and creating positive ions. Because the electrons move very quickly through the gas, they do not accumulate in the specimen-to-detector gap. However, the velocity of the positive ions is limited by diffusion.

scholarly journals X-ray laser lines in nickel-like erbium

2016 ◽  
Vol 94 (8) ◽  
pp. 705-711
Author(s):  
Wessameldin S. Abdelaziz
Keyword(s):  
Ionization Potential ◽  
Excited States ◽  
Ground State ◽  
Energy Levels ◽  
Single Electron ◽  
Electron Densities ◽  
X Ray ◽  
Electron Excited States

Energy levels of 249 excited levels in nickel-like erbium are calculated using the 3s23p63d10 as a ground state and the single electron excited states from n = 3 to n = 4, 5 orbitals, calculations have been performed using FAC code (Gu. Astrophys. J. 582, 1241 (2003). doi:10.1086/344745 ). The populations are calculated over electron densities from 1020 to 1023 cm−3 and electron temperatures 1/2, 3/4 of the ionization potential of Ni-like Er. The gain coefficients of the transitions are calculated.

scholarly journals Excited states and quantum confinement in room temperature few nanometre scale silicon single electron transistors

2017 ◽  
Vol 28 (12) ◽  
pp. 125208 ◽  
Author(s):  
Zahid A K Durrani ◽  
Mervyn E Jones ◽  
Chen Wang ◽  
Dixi Liu ◽  
Jonathan Griffiths
Keyword(s):  
Excited States ◽  
Quantum Confinement ◽  
Room Temperature ◽  
Single Electron ◽  
Single Electron Transistors ◽  
Electron Transistors

scholarly journals Accounting the effects of electron rescattering in the single-electron charge-exchange reaction

2017 ◽  
Vol 41 (0) ◽  
pp. 103-111 ◽  
Author(s):  
Володимир Юрійович Лазур ◽  
Віталій Вікторович Алексій ◽  
Світлана Іванівна Мигалина
Keyword(s):  
Exchange Reaction ◽  
Charge Exchange ◽  
Single Electron ◽  
Electron Charge ◽  
Charge Exchange Reaction

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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