Laser-ablation of metals

Huang and Freiser (132, 133) were able to prepare exohedral metal C60 ions [MC60]+ by direct reaction of the bare metal ions Fe+, Ni+, Co+, Cu+, Rh+, and La+ with Cgo vapor produced from a heated probe. The [MC60]+ ions when subjected to low-energy collision-induced dissociation with argon all produced the Cg0 ion. These results show that the metal ions attach to the outer surface of C60. The exohedral metallofullerene ions differ from the endohedral metallofullerenes produced by laser ablation of metal oxide-graphite mixtures and support the observations of Smalley and co-workers (148) who found that endohedral metallofullerene ions dissociate by loss of C2 units. 

The sols are easy to prepare (see also Lee and Meisel, 1982) and the molecules whose SERS spectra are to be obtained are added to the sol in very small concentrations (10 ". ..10 mol/1). Recently a new method for preparing SERS active colloids has been pioneered by Neddersen et. al. (1993). By means of laser ablation of metals with a Nd YAG laser operating at 1064 nm, stable Ag, Au, Pt, Pd, and Cu colloids were directly prepared in water and organic solvents. An important advantage of this method over conventional chemical procedures is that the colloids are free of organic or ionic species. Consequently, the chemical and physical effects of ions or other adsorbates can be studied under carefully controlled conditions. The authors report that the SERS activity of colloidal metals prepared by this laser ablation method is comparable or even superior to that of chemically prepared colloids. 

S. Preuss, A. Demchuk, M. Stuke, Sub-picosecond UV laser ablation of metals. Appl. Phys. A 61, 33-37, 1995. 

Pulsed laser ablation of metal samples in liquid environments by combination (in coincidence or in sequence) of two laser beams at different wavelengths has been examined in order to clarify a possibility of formation of size-selected metal nanoparticles. It has been shown that dual laser ablation technique in transparent liquids is suitable for fabrication of nanoparticles of metals where the size of particles can be controlled. The mean diameter of silver particles fabricated in water was typically in the range of 15-20 nm. 

Laser ablation of metal targets in liquids provides a rapid and simple method for preparation of stable metal nanoparticles. Advantages of this technique include its versatility with respect to metals or solvents, and the absence of chemical reagents or ions in the final preparation. The developed technique offers a good control over the particles formation process and an effective collection and conservation of fabricated materials. 

The chemical s mthesis and analysis of properties of layered nanocomposites devoted tens publications. In the last decade for the synthesis of metal, oxide, hydroxide nanostructures used method of laser ablation of metals in a liquid medium [10-12]. However, the researches aimed at producing layered organic-inorganic composites by this flexible, simple method are not enough [13]. Practically important is also the question of the structural stability of these composites in the colloidal state under the influence, in particular, laser radiation optical range (colloidal stability of drugs, film, optical data carriers, etc.). 

Laser ablation of metal alloys Si, Ge semiconductor nanowires 2.2 [74]... 

T.M. (1993) Laser ablation of metals a new method for preparing SERS active... 

Neddersen, J., Chumanov, G. and Cotton, T.M. (1993) Laser ablation of metals-a new method for preparing SERS active colloids. Applied Spectroscopy, 47,... 

SWCNTs have been produced by carbon arc discharge and laser ablation of graphite rods. In each case, a small amount of transition metals is added to the carbon target as a catalyst. Therefore the ferromagnetic catalysts resided in the sample. The residual catalyst particles are responsible for a very broad ESR line near g=2 with a linewidth about 400 G, which obscures the expected conduction electron response from SWCNTs. 

We use laser photofragment spectroscopy to study the vibrational and electronic spectroscopy of ions. Our photofragment spectrometer is shown schematically in Eig. 2. Ions are formed by laser ablation of a metal rod, followed by ion molecule reactions, cool in a supersonic expansion and are accelerated into a dual TOE mass spectrometer. When they reach the reflectron, the mass-selected ions of interest are irradiated using one or more lasers operating in the infrared (IR), visible, or UV. Ions that absorb light can photodissociate, producing fragment ions that are mass analyzed and detected. Each of these steps will be discussed in more detail below, with particular emphasis on the ions of interest. 

Further modification of the above nanostructures is useful for obtaining new functional materials. Thirdly, we apply the dopant-induced laser ablation technique to site-selectively doped thin diblock copolymer films with spheres (sea-island), cylinders (hole-network), and wormlike structures on the nanoscale [19, 20]. When the dye-doped component parts are ablated away by laser light, the films are modified selectively. Concerning the laser ablation of diblock copolymer films, Lengl et al. carried out the excimer laser ablation of diblock copolymer monolayer films, forming spherical micelles loaded with an Au salt to obtain metallic Au nanodots [21]. They used the laser ablation to remove the polymer matrix. In our experiment, however, the laser ablation is used to remove one component of block copolymers. Thereby, we can expect to obtain new functional materials with novel nanostmctures. 

Venkatakrishnan K, Tan B, Sivakumar NR. 2002. Sub-micron ablation of metallic thin film by femtosecond pulse laser. Opt Laser Tech 34 575-578. 

Historically, AuF has been one of the most elusive of all metal halides. At one time it was believed to be impossible to prepare, and theoretical papers speculating on how it might be observed or predicting spectroscopic and structural properties have been published until recently.3075- 1 The existence of AuF has been confirmed by microwave spectroscopy, the sample has been prepared by laser ablation of Au metal in the presence of a F precursor.3082 The gas-phase structure of Aul has also been determined by microwave spectroscopy.3083... 

Laser ablation of compounds of almost all elements in the periodic table will produce the bare ion M+. Laser ablation and other methods of producing bare metal ions have been discussed in Section II.C.5. The bare metal ion has a coordination number of 0 and for most elements these ions will aggressively seek molecules able to share or donate electrons. Thus most bare transition metal ions will increase their coordination number by reacting with any donor, this even includes the inert gas atoms such as Xe (96). 

Laser ablation of many metallic compounds will produce not only the bare metal ion M+ but also ions such as [MX]+, where X = O, S, Cl. The early bare transition metals ions react vigorously with background water in the mass spectrometers and the [MO]+ ion is always present when metals such as Ti are ablated. The [MX]+ ions can undergo several types of reaction and three types will be considered here substitution, addition, and polymerization reactions. Table II gives examples of the reactions of [MX]+ and [ML]+ ions. 

The reactivity of metal phosphide cations [MPJ+, and anions [MPJ , may also be studied in the gas phase. Laser ablation of mixtures of cobalt or nickel metal powders with red phosphorus gave a range of anions M PJ and cations [MPJ+ (185). The anions were unreactive, but the cations have been reacted with several neutral molecules. The ions [MPJ+, where M = Co, Ni and x = 2,4, 8, undergo five types of reactions. 

Laser Ablation of Contaminants from Concrete and Metal Surfaces... 

A Co/Ni alloy is the next active catalyst among the binary combinations within the iron-group metals in the arc discharge method (51). Laser vaporization of metal/ carbon composite in argon atmosphere at high temperature (1200°C) can also produce SWNTs (41). Guo et al. (41) reported that the Co/Ni alloy was the most effectual, with a yield of 50-90% in the laser ablation method. 

Later, McGlynn et al. (101) reported an extensive study of the gas-phase reaction of octaethylporphyrin with 12 metal monocations, which were produced by laser ablation of Al, V, Cr, Fe, Ni, Nb, Mo, Hf, W, Re, Pt, and Au targets. Three different processes were suggested charge transfer, metal-ion incorporation, and dimerization. ... 

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