Evaporation laser

Pulsed Laser Evaporation. Laser evaporation or ablation consists of using a laser emitting at an appropriate wavelength, generally a KrF excimer laser, in a pulsed mode in a controlled atmosphere to deposit a thin film of a material the composition of which is that of the target (16—18) (see... 

Laser evaporation of clusters will not be a popular technique, it is costly in equipment, demanding in know-how, and probably limited to a spectroscopic scale. Nevertheless, it has already shown itself... 

With the surface ionization source it is generally assumed that the reactant ion internal state distribution is characterized by the source temperature and that the majority of the reactant ions are in their ground electronic state. This contrasts with the uncertainty in reactant state distributions when transition metal ions are generated by electron impact fragmentation of volatile organometallic precursors (10) or by laser evaporation and ionization of solid metal targets (11). Many examples... 

The apparatus and techniques of ion cyclotron resonance spectroscopy have been described in detail elsewhere. Ions are formed, either by electron impact from a volatile precursor, or by laser evaporation and ionization of a solid metal target (14), and allowed to interact with neutral reactants. Freiser and co-workers have refined this experimental methodology with the use of elegant collision induced dissociation experiments for reactant preparation and the selective introduction of neutral reactants using pulsed gas valves (15). Irradiation of the ions with either lasers or conventional light sources during selected portions of the trapped ion cycle makes it possible to study ion photochemical processes... 

Vaivars G., Kleperis J., Zubkans J., Vitins G., Liberts G., Lusis A., Application of sol-gel and laser evaporation methods to obtain thin gas sensitive films, Proc. 8th International Conference on Solid-State Sensors and Actuators and Eurosensors IX, 1995, pp. 870-873. 

Under conditions similar to that used with CO, laser-evaporated Be atoms and C02 react during condensation in excess argon to form CO, ArBeO, BeOBe, and two new molecules in a 29 1 ratio that display CO and BeO stretching absorptions, identified as OC-BeO and the isocarbonyl CO-BeO (Equation (3)). 

FIGURE 15.2 Common protein ionization methods used for MS-based proteomics. Two common ionization technologies are currently available for protein analysis. Top ESI volatilizes and ionizes peptides and proteins in solution. Bottom MALDI uses analytes that are co-crystallized in a matrix composed of organic acid on a solid support. A pulse of ultraviolet laser evaporates the matrix and analyte into gas phase, resulting in generation of single charge ions. 

MAPLE Matrix-Assisted Pulsed Laser Evaporation... 

One technique which has produced thin, but not epitaxial films of BaPbj.xBixOg, and which shows good promise is the use of laser evaporation methods (40). Since the compound is efficiently transported stoichiometrically from the target to the substrate at a high rate and does not require a vacuum, this method may be superior to sputtering techniques. 

Zaitsev, S.V., Martynyuk, A.N. and Protasov, E.A., Superconductivity of BaPbj.jjB Oj Films Prepared by Laser Evaporation Method. Sov. Phys. Solid State 25(1) 100 (1983). 

It is characteristic of such a laser ion source that the experimental conditions for LIMS can be optimized with respect to a stoichiometric evaporation and effective ionization of solid sample material by varying the laser power density as demonstrated in Figure 2.20. Under certain experimental conditions fractionation effects can be avoided. Stoichiometric laser evaporation and ionization of analyzed material is found at a laser power density between 109Wcm 2 and 1010Wcm-2. In this laser power density range, the relative sensitivity coefficients of the chemical elements (RSC = measured element concentration/true element concentration) are nearly one for all the... 

Resonance ionization mass spectrometry as a combination of resonance laser ionization with mass spectrometry can be performed on gas atoms only. Therefore, in RIMS of solid samples, before resonance ionization, a neutral gas has to be produced using several methods known from solid state mass spectrometry. During the evaporation of solid material, e.g., by laser evaporation, thermal evaporation or by sputtering with a primary ion beam, the formation of ions should to be avoided. In RIMS, mostly the thermal evaporation of sample from a heated W or Re filament is applied. 

Fabrication methods include thermal evaporation, sputtering, magnetron sputtering, pulsed laser evaporation, molecular beam epitaxy, chemical vapor deposition, electrolytic and electroless deposition, and growth from solution. 

Meltzer et al. (2001) showed direct evidence for long-range interactions between lanthanide impurity ions in embedded nanocrystals with the TLS s of the matrix based on hole burning data. The samples were prepared as follows monoclinic 23 run Y2C>3 0.1% Eu3+ nanocrystals, produced by condensation after laser evaporation, were dispersed in a siloxane polymer. Fig. 13 shows the temperature dependence of the width of spectral holes (khb), which were burned in the 5Do <- 7Fo transition of Eu3+ ions located on the c sites (582.8 nm)innanociys-tals embedded in polymer, in comparison with the case of the free, as-prepared nanocrystals having the same size. The embedded nanocrystals exhibit a drastic increase in hole width and a very different power-law behavior for the temperature dependence of the hole widths relative to similar isolated nanoparticles. The 7 3 temperature dependence of the hole width... 

Gd Cg2 was generated by arc discharge using a Gd-graphite rod and isolated by a multistage HPLC technique SWCNT bundles were prepared by pulsed-laser evaporation. The doping of Gd C82 into the inner hollow space of SWCNTs was carried out in a sealed glass ampoule at 500 °C for 24 h. Prior to the introduction of SWCNTs to the ampoule, the SWCNTs were heated in dry air at 420 °C for 20 min [267]. 

New spatial forms of carbon - fullerenes, nanotubes, nanowires and nanofibers attract significant interest since the time of their discovery due to their unique physicochemical and mechanical properties [1-3]. There are three basic methods of manufacturing of the carbon nanomaterials (CNM) - laser evaporation, electric arc process, and catalytic pyrolysis of hydrocarbons. However, the multi-stage manufacturing process is a serious disadvantage for all of them. For example, the use of organic solvents (benzol, toluene, etc.) for separation of fullerenes from graphite soot results in delay of the synthesis process and decrease in the final product quantity. Moreover, some environmental problems can arise at this. 

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