Laser ablation, development

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. 

Laser based mass spectrometric methods, such as laser ionization (LIMS) and laser ablation in combination with inductively coupled plasma mass spectrometry (LA-ICP-MS) are powerful analytical techniques for survey analysis of solid substances. To realize the analytical performances methods for the direct trace analysis of synthetic and natural crystals modification of a traditional analytical technique was necessary and suitable standard reference materials (SRM) were required. Recent developments allowed extending the range of analytical applications of LIMS and LA-ICP-MS will be presented and discussed. For example ... 

For the majority of applications, the sample is taken into solution and introduced into the plasma as an aerosol in the argon stream. The sample solution is pumped by a peristaltic pump at a fixed rate and converted into an aerosol by a nebulizer (see atomic absorption spectrometry). Various designs of nebulizer are in use, each having strengths and weaknesses. The reader is directed to the more specialist texts for a detailed consideration of nebulizers. There is an obvious attraction in being able to handle a solid directly, and sample volatilization methods using electric spark ablation, laser ablation and electrothermal volatilization have also been developed. 

This presentation will summarize developments in laser ablation with emphasis on LIBS (laser induced breakdown spectroscopy) and inductively coupled plasma mass spectrometry (ICPMS) as analytical tools for real time chemical analysis (Fig. 1) (Russo et al. 

Mass spectrometric measurements of ions desorbed/ionized from a surface by a laser beam was first performed in 1963 by Honig and Woolston [151], who utilized a pulsed mby laser with 50 p,s pulse length. Hillenkamp et al. used microscope optics to focus the laser beam diameter to 0.5 p,m [152], allowing for surface analysis with high spatial resolution. In 1978 Posthumus et al. [153] demonstrated that laser desorption /ionization (LDI, also commonly referred to as laser ionization or laser ablation) could produce spectra of nonvolatile compounds with mass > 1 kDa. For a detailed review of the early development of LDI, see Reference 154. There is no principal difference between an LDI source and a MALDI source, which is described in detail in Section 2.1.22 In LDI no particular sample preparation is required (contrary to... 

Laser ablation is another important development, allowing solid samples to be directly analysed by ICP, since it offers the possibility of spatially-resolved microanalysis of solid samples, in a manner similar to electron microscopy, but with greater sensitivity and the potential for isotopic analysis. In this technique, a high-energy pulsed laser is directed onto a solid sample, with a beam diameter of less than 25 pm. The pulse vaporizes about 1 pg of material, to leave a crater... 

Perkins, W. T., Pearce, N. J. G., and Westgate, J. A. (1997). The development of laser ablation ICP-MS and calibration strategies examples from the analysis of trace elements in volcanic glass shards and sulfide minerals. Geostandards Newsletter 21 175-190. 

Watmough, S.A., Hutchinson, T. C., and Evans, R. D. (1998). Development of solid calibration standards for trace elemental analyses of tree rings by laser ablation inductively coupled plasma-mass spectrometry. Environmental Science and Technology 32 2185-2190. 

Wilson, S.A., Ridley, W.I., Koenig, A.E. 2002. Development of sulfide calibration standards for the laser ablation inductively-ooupled plasma mass spectrometry technique. Journal of Analytical Atomic Spectrometry 17, 406-409. 

Fabre, C., Boiron, M.-C., Dubessy, J., Moissette, a. 1999. Determination of ions in individual fluid inclusions by laser ablation optical emission spectroscopy development and applications to natural fluid inclusions. Journal of Analytical Atomic Spectrometry, 14(6), 913-922. 

Technology development is supported by the U.S. Department of Energy (DOE). The technology has been evaluated in bench-scale tests and is not currently commercially available. According to DOE researchers, laser ablation has the following advantages ... 

Cluster ion sources with different production techniques have been devised [10]. The cluster ions are produced, for instance, by vaporizing the materials using a heated oven, a laser ablation apparatus, or sputtering. Essential features of the cluster ion source are increased intensity and stability of the beam, and control of the mass distribution of the particles. Further development of cluster ion sources is in progress at several facilities [7,11]. 

The fabrication process of vanadium oxide (VO2) has also been studied using RBS/C. Since optieal and electrical properties of VO2 are dramatically changed at 68°C due to phase transition, VO2 is regarded as one of the candidates for thermally activated electronic or optical switching devices for optieal fibers or sensors. To obtain the desired properties, the development of the fabrication process for very thin films, without crystalline defects on various substrates, is required. Single-crystalline VO2 thin films on (0001) plane of a sapphire substrate have been synthesized by a laser ablation method. The quality of VO2 was examined by X-ray diffraction and RBS/C method. The eleetrieal resistanee and the optical transmittance of the VO2 film were measured under inereasing and deereasing temperatures. At a temperature of 68 °C, an abrupt transition of resistanee from metal to... 

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