About methodical errors in studies of mass transfer processes induced by intense pulsed ion beams in solids
The present paper briefly discusses the questions of accuracy of depth profiling techniques in studies of mass transfer processes induced by intense pulsed ion beams (IPIB) in solids. The best measurement tools provide good precision only. An acceptable reproducibility, correctness, and, finally, accuracy of measurement are a result of complete elimination all of the systematic errors. The first ones are caused by a dependence of main SIMS and AES analytical characteristics, ionization coefficients and sputtering factors, on a degree of IPIB exposure. It is shown that the preferable application of nuclear analysis methods, RBS and PIGE, avoids these errors. A mechanical polishing conventionally applied for surface preparation of specimens under investigation engenders to unpredictable changing of mechanical, electric and thermodynamic properties of the surface layer, for at least 1 /spl mu/m depth in the case of Cu surface polishing and for the depth less than the previous one by the factor of 3-5 for /spl alpha/-Fe, steel, Zr, etc. Surface preparation with electrochemical polishing allows a second kind of error to be avoided. A third kind of systematic error is connected with vagueness of the main IPIB parameters (ion species, energy distribution, flux) at the investigated section of the modified sample. Use of more detailed specimens analyzed by cross section is suggested in order to avoid these errors.
Relation between Residual Polishing Agent and Material Hardness Determined by a Narrow Nuclear‐Reaction Resonance Technique
Clean smooth solid surfaces needed in certain investigations are often prepared with the aid of fine polishing powders, which may remain on the surface as residual contaminant. The present paper reports on the alumina and magnesia retentivity of twelve different metal surfaces as measured by a novel technique involving the use of strong sharp resonances in the nuclear reactions 27Al(p,γ) 28Si and 26Mg(p,γ) 27Al. This technique has high sensitivity and, because of the sharpness of the resonances, also provides information on the penetration depths of the residual polishing agents as well as on the amounts present. A plot of the amount of residual polishing agent vs the hardness of the surface showed a general trend for the retentivity to be less with increase in solid hardness. Divergence from this trend was noted for metals which have other than cubic crystal structures; zinc and cadmium, two of the three softest metals, retained not only very small amounts of residue but also tended to keep this residue ...
Formation of unexpected ions from a first-generation polyamidoamine dendrimer by use of methanol: an artefact due to electrospray emitter corrosion?
We report the formation of unexpected ions during the analyses of a first-generation polyamidoamine dendrimer in negative ion mode using an ion trap equipped with an electrospray ionisation source. These surprising ions corresponded to an increase of 12 m/z units over those expected. The formation of the unexpected ions was dependent on the tuning of the solution flow rate and the capillary high voltage. In addition, measurements of unusual value of the current suggested that a reaction was occurring in the corona plasma. The influence of methanol in this phenomenon was demonstrated by using CD(3)OH in the sample preparation. We propose two structures to explain the observed adduct based on the results of MS(2) experiments and by referring to previous work dealing with 12 m/z units addition. We showed that a corona discharge caused by alterations taking place to the electrospray capillary emitter was the origin of these unexpected ions. Finally, we discuss the mechanism involved in the formation of the ions and we propose means to control such artefacts.