Molecular effects in ion-electron emission from clean metal surfaces

Baragiola, R. A.; Alonso, E.V.; Auciello, O.; Ferrón, J.; Lantschner, G. H.; Florio, A.Oliva

doi:10.1016/0375-9601(78)90494-2

Cited by 31 publications

(2 citation statements)

References 6 publications

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“…For hydrogen projectiles on clean metals, previous studies indicate that the ratio of the yields ␥(H 2 ϩ ,)/2␥(H ϩ ,) at equal velocity is less than one below ϳ4.5ϫ10 8 cm/s and larger than one at higher velocities. 2,[39][40][41][42] The reduction at low velocities occurs even taking into account a smaller potential electron emission yield by molecular ions. 6 A similar effect has been observed for hydrogen clusters traversing thicker (у7.2 g/cm 2 ) carbon foils at energies above 40 keV/amu by Rothard et al 43 Figure 8 shows our secondary electron measurements for H 2 ϩ projectiles.…”

Section: Resultsmentioning

confidence: 99%

Electron emission from carbon foils induced by keV ions

Ritzau

Baragiola

1998

Phys. Rev. B

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We have measured yields of electrons emitted in the forward and backward directions from ultrathin carbon foils due to 10-100 keV atomic and molecular projectiles. In general, electron yields are higher in the forward than in the backward direction. Their behavior with projectile type and energy can be explained by a competition of a forward peaked angular distribution of initial ionization events and elastic collisions that tend to randomize electron motion in the foil. Experiments with ions with atomic number Zϭ1-10 indicate that heavy projectiles produce less electron emission per amount of deposited energy by the projectile near the surface. This is attributed to a larger fraction of low-energy electrons produced by heavy projectiles in the primary ionization event that cannot surmount the surface barrier. For incident molecules, the backward electron yield is less than the sum of the yields of the constituent atoms. Neutral atoms with relatively low ionization potentials produce higher electron yields in the backward direction than the ions of the same species for incident energies above about 5 keV/amu, which is attributed to electron loss from the projectile.

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Section: Resultsmentioning

confidence: 99%

Electron emission from carbon foils induced by keV ions

Ritzau

Baragiola

1998

Phys. Rev. B

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“…Experimentally, almost no molecular effect is measured [45,46], although sometimes twice the yield of O + is found to be 10%-30% higher than the yield of + O 2 , at the same bombarding velocity [40,[47][48][49][50][51]. The reason for the molecular effect is not known at present [49,52,53], but Ferrón et al [54] suggest that if the oxygen ion beam contains a fraction f of the ion + O 2 2 , then the atomic yields would increase by a factor 1 + 2f. The two different mechanisms are considered to be detachable, so the total electron emission yield is written as…”

Section: Secondary Electron Emission Yield For Oxygen Bombarding Metalsmentioning

confidence: 95%