K. O. Groeneveld

Ion induced electron ejection from solids

Abstract Electrin energy spectra, their angular distribution and their total yield γ give information on electron production mechanisms in energetic ( 1 E M 3 keV/amu ) ion-solid interaction. From molecular ion induced total electron yield data we report on a novel interference effect of electron density waves in a solid.

Strong molecular effects in zero degree electron emission from molecular ions after solid foil interaction

Abstract The total yield and the yield of zero degree electrons has been measured over a wide range of dwell times (0.5 to 20 fs) in carbon foils for different atomic (H + and He + at 1.7 MeV/n; Ti 14+ and U 44+ at 1.4 MeV/n) and molecular (H 2 + and H 3 + at 1.7 MeV/n) projectiles. Strong molecular effects are observed both in the electron energy spectra and in the dwell time dependence.

Strong dwell-time dependence of convoy electrons from atomic and molecular projectile ion in thin carbon foisl

Angular — and velocity — distributions of electrons emitted near zero degree from projectile ions (H+, H2+, H3+, He+, He++ at 1.7 MeV/u) traversing solid carbon foils (2 to 20) μg/cm2) have been measured. The data give clear evidence of production mechanisms which go beyond those reported elsewhere.

Untersuchungen zur Struktur des Kerns23Ne

Low-lying states of23Ne up to about 3 MeV excitation energy have been investigated by studying the reactions22Ne(d, p)23Ne (Ed=4–6 MeV) and23Na(n, p γ)23Ne(En=8–9 MeV). From the (d, p) data,l-values and spectroscopic factors for the transferred neutron have been extracted by DWBA analyses. From the (n, p γ) data,γ-ray branchings and possible spin assignments have been derived. The results are used to discuss the applicability of the Nilsson model and the excited core model to the nucleus23Ne.

K-Ionization probability across the 460-keV12C(p, p0) resonance

We have remeasured theK-shell vacancy production probabilityPK across the 460-keV12C(p, p0) resonance, previously investigated by Duinker et al. We are unable to confirm the large (∼70 %) variation ofPK across the resonance, found by Duinker et al. for protons elastically scattered at 125°. Our values for the ratioPK(142°)/PK(16°) are independent (within±20%) of the proton bombarding energy over the resonance region, in agreement with theoretical predictions by Blair and Anholt, Feagin and Kocbach, McVoy and Weidenmüller. Our average value for this ratio, equal to 0.88 ±0.06, agrees with the value 0.88 calculated by Amundsen and Aashamar.

Electrons from target and projectile ionization in simple collision systems

SummaryAbsolute double differential cross-sections for target ionization and projectile electron loss were determined in collisions of H+, H2+,3He+ and3He++ ions (0.4 to 2.0 Me V/u) with He and Ar gas targets at electron emission angles from 0° up to 60°. The experimental results are qualitatively well described by plane-wave Born approximations including screening of the projectile in target ionization and of the target atom in the case of electron loss.RiassuntoSono state determinate le sezioni d’urto doppie differenziali assolute per la ionizzazione del bersaglio e la perdita dell’elettrone proiettile in collisioni di ioni H+, H2+,3He+ e3He++ (da 0.4 a 2.0 Me V/u) con bersagli di gas He e Ar ad angoli di emissione degli elettroni da 0° a 60°. I risultati sperimentali sono qualitativamente ben descritti dalle approssimazioni di Born per onde piane che comprendono la schermatura del proiettile nella ionizzazione del bersaglio e dell’atomo bersaglio nel caso di perdita dell’elettrone.РезюмеОпределяются абсолютные дважды дифференшиальные поперечные сечения для ионизации мишени и потери электровов налетающими частишами при соударениях ионов H+, H2+,3He+ и3He++ (от 0.4 до 2.0 Me V/u) в случае газовых Не и Ar мишеней при углах эмиссии электронов от 0° до 60°. Экспериментальные результаты качественно хорощо описываются с помощью плоско-волнового борновского приближения, включая экранирование налетающей частицы при ионизации мишени в случае потери электрона.

Carbon auger electron line shape after beam-foil excitation of molecular ions

Auger electrons of beam-foil excited C-projectiles and C-fragments of Coulomb exploding molecular CO-projectiles at 83 keV/u yield information on the excitation mechanisms and the interaction with the solid. A numerical procedure is developed to calculate the mean energy of the Coulomb explosion, the charge states of the fragment ions and their angular straggling behaviour inside the solid. The calculated results are compared with experimental data. From a detailed line shape calculation the magnitude of directional effects induced by the Wake-potential can be predicted.