Cold ion beams

In the last paragraph of this report some brief comments are made concerning the usefulness of resonant multiphoton ionization for the construction of an cold ion beam source and the diagnostic use of photo-ionization in collisional energy transfer studies /4/. 

Some physical techniques can be classified into flame treatments, corona treatments, cold plasma treatments, ultraviolet (UV) treatment, laser treatments, x-ray treatments, electron-beam treatments, ion-beam treatments, and metallization and sputtering, in which corona, plasma, and laser treatments are the most commonly used methods to modify silicone polymers. In the presence of oxygen, high-energy-photon treatment induces the formation of radical sites at surfaces these sites then react with atmospheric oxygen forming oxygenated functions. 

The sample was analysed with a primary ion beam of extracted from an oxygen cold cathode discharge type source. A well-focussed 200 nA spot was attained at 4keV per molecular ion. The beam was scanned over a square of side 400 pm to produce a uniform primary beam current density and thus a flat-bottomed crater. In order to eliminate crater-edge effects, the counting system was only enabled when the centre of deflection of the beam was in a central area 125 x 125 pm. 

Figure 4. Comparison of measured dissociative recombination cross sections for H. Inclined-beam results for cold ions (triangles with dots, from ref. 38). Afterglow results for cold ions (open squares with dots, from ref. 15). Merged-beam results (from ref. 23) for excited ions (solid circles), for cold ions (open squares) (from ref. 23), and for ions with intermediate vibrational excitation (solid squares and open circles).

The result of intensity alternation for the boron nitride cluster ions is in accordance with the generation of high cluster ion beams MnXn, for several systems (e.g. NaCl, CuBr or Csl26 49) by other methods of cluster formation such as by quenching condensation in a cold rare gas or by ion bombardment of hahdes. 

The decay of the valence state of the bare TDMAE molecule has been analysed in a cold supersonic beam after excitation at 266 nm, in a former work[6]. The ionisation potential of TDMAE is sufficiently low that excitation of the valence state at 266 nm allows probing the V state at 800 nm with an excess energy of 0.8 eV. The monotonic decay of the V state was observed with a 300 fs time constant. This decay is accompanied by the simultaneaous rise of the Z state detected with two 800 nm photons. This latter state further decays in 100 ps. This results in a bi-exponential signal for the TDMAE+ ions. 

Actinides served already as targets, when neutron capture and subsequent P decay were used for the first synthesis of transuranium elements. Later, up to the synthesis of seaborgium, actinides were irradiated with light-ion beams from accelerators. At that time it was already known that cold fusion reactions yield higher cross sections for heavy element production. 

Fig. 20.3. The upper diagram shows the ion beam profiles of the Cl l) and OoH.j parent ions and Ar+ in the z-direction. The ion signal was measured as a function of the voltage on the z-deflector pair. The electron energy was set to 100 eV. In the lower diagram the initial ion kinetic energy distributions were calculated from these z-profiles and compared to Ar that has been introduced as a cold gas jet...

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