Plasma-assisted ablation

The requirements of thin-film ferroelectrics are stoichiometry, phase formation, crystallization, and microstmctural development for the various device appHcations. As of this writing multimagnetron sputtering (MMS) (56), multiion beam-reactive sputter (MIBERS) deposition (57), uv-excimer laser ablation (58), and electron cyclotron resonance (ECR) plasma-assisted growth (59) are the latest ferroelectric thin-film growth processes to satisfy the requirements. 

The capabilities of two plasma assisted techniques (laser ablation and electrical discharge in liquids) for fabrication of nanoscale composite (Al-Cu/oxide matrix), zinc oxide and doped gadolinium oxide have been piesented. 

In the present paper, the laser/plasma assisted techniques for fabrication of Al-Cu/oxide matrix particles, doped gadolinium oxide and zinc oxide are considered. They offer advantages eliminating the need in large-scale vacuum system since the laser ablation and discharges are performed at normal pressure and they offer a good control over the synthesis process. 

Mitu B, MarottaV, Orlando S. Multilayered metal oxide thin film gas sensors obtained by conventional and RF plasma-assisted laser ablation. Appl. Surf. Sci. 2006 252(13) 4637-4641. DOI 10.1016/j.apsusc.2005.07.102. 

Many methods have been reported for production of nanodiamonds (NDs) such as laser ablation, " plasma-assisted chemical vapor deposition," autoclave synthesis from supercritical fluids, ion irradiation of graphite, chlorination of carbides, electron irradiation of carbon onions, and ultrasound cavitation. Smaller NDs can be prepared by detonation processes that yield aggregates of NDs with sizes of 4-5 nm embedded in a detonation soot composed of other carbon allotropes and impurities. An explosive mixture having an overall negative oxygen balance provides a source of both carbon and energy for the conversion. Because of their small size (2-10 nm) detonation NDs have also been referred to as ultradispersed, nanocrystalline... 

Cubic BN can also be obtained at low pressure in the field of stability of h-BN under nonequilibrium conditions, in analogy to the formation of diamond or diamond-Hke carbon films. As in the case of diamond, CVD, plasma-assisted chemical vapor deposition (PACVD), and PVD methods such as ion beam bombardment, radiofrequency sputter deposition, laser ablation, and magnetron sputtering can each be appHed. 

The ablated vapors constitute an aerosol that can be examined using a secondary ionization source. Thus, passing the aerosol into a plasma torch provides an excellent means of ionization, and by such methods isotope patterns or ratios are readily measurable from otherwise intractable materials such as bone or ceramics. If the sample examined is dissolved as a solid solution in a matrix, the rapid expansion of the matrix, often an organic acid, covolatilizes the entrained sample. Proton transfer from the matrix occurs to give protonated molecular ions of the sample. Normally thermally unstable, polar biomolecules such as proteins give good yields of protonated ions. This is the basis of matrix-assisted laser desorption ionization (MALDI). 

The ionization methods reported for IMS included MALDI [41,76-80], Secondary Ion Mass Spectrometry (SIMS) [19, 81-86], Matrix-enhanced (ME)-SIMS [87, 88], Desorption Electrospray Ionization (DESI) [89-99], Nanostructure Initiator Mass Spectrometry (NIMS) [100-102], Atmospheric Pressure Infrared MALDI Mass Spectrometry (AP-IR-MALDI-MS) [103], Laser Ablation-inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) [104-106], Laser Desorption Postionization (LDPI) [107], Laser Ablation Electrospray Ionization Mass Spectrometry (LAESI) [108, 109], and Surface-assisted Laser Desorption/ioniza-tion Mass Spectrometry (SALDI) [110-112], Another method was called probe electrospray ionization (PESI) that was used for both liquid solution and the direct sampling on wet samples. 

Ion-assisted gas-surface chemistry mechanism is probably the best terminology to describe the plasma processing of a surface. A remarkable illustration of the effect of ion bombardment is reported in Fig. 16 [66]. The reaction rate of XeF2 with Si increases drastically upon the simultaneous combination of chemical species (XeF ) and ions (Ar+) on the surface. Obviously chemical reaction and some sputtering processes are expected to occur and to be responsible of the ablation of the material, but the combined effect of active neutral species and ion bombardment is more efficient than the sum of the individual processes. 

Several attempts have been made to synthesize thin film C3N4, be it cubic or hexagonal. These include reactive magnetron sputtering [184-187], laser ablation [188] ion beam assisted deposition (IBAD) [189], plasma [191, 192] and plasma-enhanced chemical vapour deposition [190]. 

Russo, R.E., Mao, X.L., Liu, C, Gonzalez, J. (2004) Laser assisted plasma spectrochemistry laser ablation. Journal of Analytical Atomic Spectrometry, 19,1084-1089. 

Becker, J. Su., Mounicou, S., Zoiiy, M. V., Becker, J. S., Lobinski, R (2008) Analysis of metal-binding proteins separated by non-denaturating gel electrophoresis using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Talanta, 76, 1183-1188. 

The relation between acoustic and optical signals produced at UV-LA-ICP-AES spectrometry was discussed [81]. Moenke-Blankenburg [38] has described laser ablation for solid sample introduction for inorganic analysis. Arrowsmith [82] and Durrant [82a] have reviewed laser-assisted elemental analysis of solids by secondary plasma source mass spectrometry. 

Figure 1.13 Selected analytical techniques used for metallomics studies. ICP-OES, inductively coupled plasma optical emission spectroscopy, ICP-MS, inductively coupled plasma mass spectrometry LA-ICP-MS, laser ablation ICP-MS XRF, X-ray fluorescence spectroscopy PIXE, proton induced X-ray emission NAA, neutron activation analysis SIMS, secondary ion mass spectroscopy GE, gel electrophoresis LC, liquid chromatography GC, gas chromatography MS, mass spectrometry, which includes MALDI-TOF-MS, matrix-assisted laser desorption/ ionization time of flight mass spectrometry and ESI-MS, electron spray ionization mass spectrometry NMR, nuclear magnetic resonance PX, protein crystallography XAS, X-ray absorption spectroscopy NS, neutron scattering.

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