摘要:

The detailed dependences of the parameters of fast ionized recoil flux ejected from both single- and polycrystalline copper targets under 30 keV Ar ion bombardment on experimental geometry and target temperature have been obtained. It has been found that the target temperature may strongly affect the fast-recoil ejection from the single-crystal target. The strongest temperature effects take place in the case of aligned target orientation. The effect of the geometric factors of the experiment diminishes with rising target temperature, so that the parameters of the recoil flux at sufficiently high temperatures for a single-crystal target become the same as in case of a polycrystal target. The effect of thermal vibrations of lattice atoms on the process of fast-recoil ejection is analyzed in terms of the model of a vibrating isolated atomic row. The method is described in detail for calculating the energy distributions of the ejected atoms with due account of the correlation of thermal displacements of lattice atoms. The contribution of each type of ejection mechanism to the ejected recoil flux is estimated. The effect of double focusing of fast recoils on their energy distributions is demonstrated. The calculations have been found to represent correctly the form of the observed energy distributions of recoils and the temperature dependences of some of their parameters.

ISSN:0033-7579    

DOI:10.1080/00337578408222494

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

In this paper the measurements of the dependence of track etch rate on the specific energy loss, (dE/dx) of different charged particles are presented. In the method, 6C12, 8O16, 10Ne22-ions of energy 5.5 MeV/N and 18Ar40-ions of energy 7.5 MeV/N are used as energetic heavy ions for track formation in Makrofol Polycarbonate track detector. The maximum etched track lengths of these ions are compared with the theoretically computed ranges. The bulk etch rate and track etch rate are determined for different temperatures ranging from 50°C to 90°C. The experimental results show that the track registration sensitivity of Makrofol plastic detector exposed to heavy ions remains constant between 50° and 90°C. The normalized track etch rate,V=Vt/Vbdepends only on dE/dx and not on the etching temperature. The variation of normalized track etch rate along the particle trajectory is also shown for different temperatures. Moreover, the experimental data are presented for the influence of different annealing conditions on bulk etch rate, etchpit diameter and etchable range of 18Ar40-ion in Makrofol Polycarbonate detector.

ISSN:0033-7579    

DOI:10.1080/00337578408222495

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Fast ion induced desorption yields of positive secondary ions of different biomolecules have been studied with a time-of-flight technique. The yields were studied as a function of energy deposition of the primary ion. The samples used were an amino acid, two protected oligonucleotides and a small protein (bovine insulin). Different primary ions with constant velocity were used throughout the experiment. In this way the energy density or electronic stopping power was changed by using different primary ions. It was found that for low energy densities the yields increase with different powers of the energy density for the different systems. For high energy densities the yields are proportional to the energy density for all systems studied. The results indicate that for large molecules multiple bond breaking is needed for desorption to occur. For the amino acid sample (valine) an extensive clustering effect was also found. Cluster ions containing as many as 20 valine molecules were observed. This work was supported by the Swedish Natural Science Research Council.

ISSN:0033-7579    

DOI:10.1080/00337578408222496

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

An investigation was undertaken of the elastic interaction of a relativistic electron with the excitations of the electron-phonon system in its movements through a thin crystal at a small angle towards the crystallographic directions. Examination showed that the initial pure state of the electron is changed to an incoherent mixture as a result of interaction with the excitations. The law of the attenuation of non-diagonal elements of the density matrix of electrons interacting with Bose and Fermi-excitations is investigated.

ISSN:0033-7579    

DOI:10.1080/00337578408222497

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor