Ion plating vacuum-based

Two basic versions of the process plasma-based ion plating and vacuum-based ion plating. The coating material is vaporized in a manner similar to evaporation. Typically, the plasma is obtained by biasing the substrate to a high negative potential (5 kV) at low pressure. The constant ion bombardment of the substrate sputters off some of the surface atoms which results in improved adhesion and reduced impurities. Surface coverage of discontinuities is also improved. 

In ion-plating deposition, the substrate and the deposited film (as it forms) are subjected to bombardment by particles (ions, atoms, molecules) which alter the formation process and the properties of the coating.l ll l The process is also called ion-beam assisted deposition (IBAD). Two basic versions of the process, plasma-based ion plating and vacuum-based ion plating, are illustrated in Figs. 15.8 and 15.9. 

Figure 9.1 Ion Plating Configurations (a) Plasma-Based Ion Plating and (b) Vacuum-based Ion Plating...

Ion beam-assisted deposition (IBAD) (film deposition) A special case of ion plating where the deposition is done in a high vacuum and the concurrent or periodic bombardment is provided by gaseous ions accelerated from an ion gun or plasma source. Also called Vacuum-based ion plating, Ion beam-enhanced deposition, and Ion-assisted deposition (lAD). 

Vacuum-based ion plating (film deposition) See Ion beam-assisted deposition (IBAD). 

Fig. 11. Ion plating configurations (a) plasma-based, where the substrate fixture is the cathode of the d-c circuit, and (b) vacuum-based (IBAD).

IBAD experiments were performed using a resonance vacuum arc ion source. This type of ion source with desirable metal (Me) electrodes was used to produce a mixture of neutral Me and Me+ ion species. Substrate plates (silicon and rubber) were floated to a negative potential with respect to the source of 3 keV to accelerate the ion species. The deposition and irradiation of Ti, Zr and Mo coatings have been accomplished simultaneously on silicon (n-type, 200 Q cm) and on rubber (GOST V-14) samples. The base pressure of the target chamber was 10 2 Pa. The relative ratio of ions/neutral atoms and deposition rates were found to be 0.2-0.4 and 0.3-0.4 nm/min in different sets of experiment. 

Figure 15.9 Schematic representation of ion-plating apparatus using a vacuum-based configuration with electron-beam evaporator.

A schematic of a MALDI-TOF-MS instrument is depicted in Figure 11.2b. Samples, consisting of a few microlitres of analyte solution (with or without matrix), are deposited on a MALDI target (Figure 11.2a). After the solvent has evaporated the sample plate, carrying the solidified samples, is introduced into the MALDI ionization chamber via load-lock. The ionization process takes place in a high-vacuum chamber to which the plate is introduced via a prechamber kept at a pressure lower than atmospheric. Analyte ions are then accelerated as they are formed and pumped into the TOF analyzer, where they are separated based on their mass-to-charge ratio. 

On-chip Reaction and Analysis. To prove the principle of the monitoring window , the Schiff base formation reaction between 2 and 4 in ethanol (Scheme 11.1) was carried out using the MALDI-chip device equipped with the chip of Figure 11.9. The chip placed on the MALDI sample plate was introduced into the vacuum chamber by load-lock. The first MALDI-TOF mass spectrum was acquired as soon as the plate reached the right spot in the chamber. The analysis started after about 1 min. Ions were extracted from the... 

Another very sensitive detection scheme is based on resonant two- or three-photon ionization of atoms and molecules in the gas phase (Sect. 6.3). With this technique even liquid or solid samples can be monitored if they can be vaporized in a furnace or on a hot wire. If, for instance, a heated wire or plate in a vacuum system is covered by the sample, the atoms or molecules are evaporated during the pulsed heating period and fly through the superimposed laser beams L1+L2 (+L3) in front of the heated surface (Fig. 15.2). The laser LI is tuned to the resonance transition /> - k) of the wanted atom or molecule while L2 further excites the transition k) f). Ions are formed if Ef is above the ionization potential IP. The ions are accelerated toward an ion multiplier. If L2 has sufficient intensity, all excited particles in the level / ) can be ionized and all atoms in the level [/ flying through the laser beam during the laser pulse can be detected single-atom detection) [15.10-15.12]. If... 

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