Metal foil, surface preparation

Moreover, recent methods for the synthesis of MNPs in ILs, such as sputtering deposition and phase transfer, can also be mentioned. In sputtering deposition, the bombardment of a metal foil surface with energetic gaseous ions causes the physical ejection of surface atoms and/or small clusters that are stabilized by the IL [19, 20]. Phase transfer consists of the preparation of MNPs in water or organic solvents, which are then transferred to an IL phase [21-23]. These methods afford stabilized MNPs in ILs that are efficient catalysts for several reactions. 

Figure 3. Surface preparation of the polycrystalline iron foil as received, with damage from cold work (a), ion etched, to remove 2 fan of metal (b) after annealing for 2 hat 500°C to remove etch structure (c), and development of step structure after further annealing for 3 hat 600°C (d).

All mass spectra were obtained with a Fourier transform ion cyclotron resonance mass spectrometer (FTMS). The theory and applications of FTMS spectrometry are well-established and will not be discussed here. In our apparatus the sample was located at one of the trap plates of the cell, inside a superconducting magnet. Two pulsed lasers were used, one for tire PFPE desorption and another for metal ion formation. Typically, 2 to 4 mj/pulse of 248 nm or 193-nm light (20 ns fwhm) from an excimer laser was softly focused to an elliptical spot with a 2-mm long axis for desorption. To create the metal ions, a 0.3-mJ pulse of 532-nm light (10 ns fwhm) from the doubled output of a Nd YAG was tightly focused. The metal substrates were prepared from foils of various metals (typically 0.010 in. tiiick). Surface preparation was not critical because the experiment was not sensitive to PFPE/metal surface interactions since the thickness of the polymer films was on the order of 1 pm. 

The foils are prepared by vacuum evaporation from a carbon arc on to microscope slides which have first been coated with a thin film of soap or detergent. The carbon film can be floated off on water and pieces mounted on thin metal frames. The amount of light produced by the foils depends on their thickness but owing to surface contamination, foils of equal thickness do not necessarily produce equally intense excitation of the beam. 

In the early days of TEM, sample preparation was divided into two categories, one for thin films and one for bulk materials. Thin-films, particularly metal layers, were often deposited on substrates and later removed by some sort of technique involving dissolution of the substrate. Bulk materials were cut and polished into thin slabs, which were then either electropolished (metals) or ion-milled (ceramics). The latter technique uses a focused ion beam (typically Ar+) of high-energy, which sputters the surface of the thinned slab. These techniques produce so-called plan-view thin foils. 

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