Impact parameter dependence of the electronic energy loss of fast cluster projectiles

Electronic energy loss of molecular clusters as a function of impact parameter is less understood than atomic energy loss. Vicinage effects due to mutual interference between cluster fragments play a key role in the determination of the cluster electronic energy loss. In this work, we describe a molecular extension of the perturbative convolution approximation PCA energy loss model, namely MPCA molecular PCA , which yields remarkable agreement with first order Born semiclassical approximation SCA results. The physical inputs of the model are the oscillators strengths of the target atoms and the projectile electron density. A very good agreement is obtained with time consuming full first order calculations for bare incident molecular clusters for several angles between cluster axis and velocity directio

Search for short time phase effects in the electronic damage evolution A case study with silicon

This work focusses on the production and decay properties of inner shell vacancies and valence band excitations induced by swift highly charged ions interacting with amorphous and crystalline Si. High resolution electron spectra have been taken for fast heavy ions at 1.78 5 MeV u as well as for electrons of similar velocity incident on atomically clean Si targets of well defined phase. Various Augerelectron structures are analyzed concerning their width, their intensity and exact peak position. All measured peaks show a small shift towards lower energy when the charge of the projectile is increased. This finding is an indication for a nuclear track potential inside the ion track. A detailed analysis of the Auger electron spectra for amorphous Si and crystalline Si 111 7 x 7 points to a small but significant phase effect in the short time dynamics of ion track

The influence of the Coulomb explosion on the energy loss of H2 and H molecules channeling along the Si lt;100 gt; direction

In this work we have measured the contribution of the Coulomb explosion to the electronic stopping power of molecular hydrogen ions H 2 and H 3 channeling along the Si h100i direction. We have used a SIMOX target, consisting of crystalline Si h100i with a buried layer of SiO2. The measurements of the energy loss of H , H 2 and H 3 have been carried out using the standard channeling Rutherford backscattering spectrometry. The energy loss has been measured around the Si h100i channel at a fixed energy per nucleon 150 keV amu as a function of the tilt and azimuthal angles. The present results show the effect of Coulomb explosion, which enlarges the protons traversal energy and consequently the channeling energy loss. This heating effect due to H 3 ions is about two times larger than H 2 molecules and amounts to about 5 of the total stopping powe

Stopping power of Zn for heavy ions

We present stopping power measurements of Zn for C and O ions and compare them with a theoretical description given by the Transport Cross Section - Extended Friedel Sum Rule (TCS-EFSR) for the valence electrons, and two different models for the inner-shells: the Shellwise Local Plasma Approximation (SLPA) and the CasP approach. The SLPA, which successfully applies to projectiles from H to B, is slightly high for C ions and clearly overestimates the data for O ions. On the other hand, total stopping results using the CasP description for the inner-shells show good agreement with the data for C and O ions, and also with the SRIM predictions. © Published under licence by IOP Publishing Ltd.Fil:Montanari, C.C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Behar, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Miraglia, J.E. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Al K Auger Energy Spectra Probing the Electron Dynamics in Ion Solid Interactions

K Auger electron emission has been investigated for incident electrons and for different types of heavy ions interacting with mono crystalline aluminum 100 targets at specific kinetic energies of 3 to 5MeV u. In an effort to gain a profound knowledge about the ionization and vacancy decay dynamics for the K shell in Al, spectra have been measured with different energy resolutions and angular distributions have been taken as well. Here we concentrate on the energy spectra; we identify the measured peak structures and we investigate different line intensities and mean target charge states quantitatively, in comparison with theoretical result

Al K Auger electron emission A sensitive probe of the electron dynamics in ion solid interactions

Auger energy and angular distributions serve as sensitive probes of the atomic and electronic solid state structure, of the excitation dynamics during the interaction of fast ions with solid matter and of the subsequent vacancy decay dynamics, involving also the atomic and electronic material properties. In this work, we will concentrate on the short time dynamics, especially on the energy spectra with less attention on the geometrical sample structur

Ground and excited state scattering potentials for the stopping of protons in an electron gas

The self consistent electron ion potential V r is calculated for H ions in an electron gas system as a function of the projectile energy to model the electronic stopping power for conduction band electrons. The results show different self consistent potentials at low projectile energies, related to different degrees of excitation of the electron cloud surrounding the intruder ion. This behavior can explain the abrupt change of velocity dependent screening length of the potential found by the use of the extended Friedel sum rule and the possible breakdown of the standard free electron gas model for the electronic stopping at low projectile energies. A dynamical interpolation of V r is proposed and used to calculate the stopping power for H interacting with the valence electrons of Al. The results are in good agreement with the TDDFT benchmark calculations as well as with experimental dat