Heating laser

Yoo C S, Akella J and Nicol M 1996 Chemistry at high pressures and temperatures in-situ synthesis and characterization of p-SijN by DAC x-ray/laser-heating studies Advanced Materials 96 ed M Akaishi et al (Tsukuba National Institute for Research in Inorganic Materials) p 175... 

Ditmire T, Zweiback J, Yanovsky V P, Cowan T E, Hays G and Wharton K B 1999 Nuclear fusion from explosions of femtosecond laser-heated deuterium clusters Nature 389 489-92... 

Other vapor introduction systems are discussed in Parts B and C (Chapters 16 and 17) because, although liquids and solids are ultimately introduced to the plasma flame as vapors, these samples are usually prepared differently from naturally gaseous ones. For example, electrothermal (oven) or laser heating of solids and liquids to form vapors is used extensively to get the samples into the plasma flame. At one extreme with very volatile liquids, no heating is necessary, but, at the other extreme, very high temperatures are needed to vaporize a sample. For convenience, the electrothermal and laser devices are discussed in Part C (Chapter 17) rather than here. 

Suffice it to say at this stage that the surfaces of most solids subjected to such laser heating will be heated rapidly to very high temperatures and will vaporize as a mix of gas, molten droplets, and small particulate matter. For ICP/MS, it is then only necessary to sweep the ablated aerosol into the plasma flame using a flow of argon gas this is the basis of an ablation cell. It is usual to include a TV monitor and small camera to view the sample and to help direct the laser beam to where it is needed on the surface of the sample. 

Fig. 4. Hardness—depth curve for case hardening of 0.6 wt % C steel by laser heating (7).

Fig. I. Field emission dala from a mounted nanotube. An activated nanotube emits a higher current when heated by the laser than when the laser beam is bloeked (a). When aetivated by exposing the nanotube to oxygen while heating the tip, this behavior is reversed, and the emission current increases dramatically when the laser is blocked. The activated state can also be achieved by laser heating while maintaining a bias voltage of —75 V. Note that the scale of the two plots is different the activated current is always higher than the inactivated current. As discussed in the text, these dala led to the conclusion that the emitting feature is a chain of carbon atoms pulled from a single layer of the nanotube —an atomic wire.

T-Jumps can also be produced by microwave heating and by laser pulse absorption. These methods remove the restriction to low-resistance solvents any solvent capable of absorbing energy of the applied frequency may be used. The heating time can be extremely short with laser heating. ... 

The predominant gaseous products of the decomposition [1108] of copper maleate at 443—613 K and copper fumarate at 443—653 K were C02 and ethylene. The very rapid temperature rise resulting from laser heating [1108] is thought to result in simultaneous decarboxylation to form acetylene via the intermediate —CH=CH—. Preliminary isothermal measurements [487] for both these solid reactants (and including also copper malonate) found the occurrence of an initial acceleratory process, ascribed to a nucleation and growth reaction. Thereafter, there was a discontinuous diminution in rate (a 0.4), ascribed to the deposition of carbon at the active surfaces of growing copper nuclei. Bassi and Kalsi [1282] report that the isothermal decomposition of copper(II) adipate at 483—503 K obeyed the Prout—Tompkins equation [eqn. (9)] with E = 191 kJ mole-1. Studies of the isothermal decompositions of the copper(II) salts of benzoic, salicylic and malonic acids are also cited in this article. 

Valley, J.W., Kitchen, N., Kohn, M.J., Niendorf, C.R. and Spicuzza, M.J. 1995 UWG-2, a garnet standard for oxygen isotope ratios strategies for high precision and accuracy with laser heating. Geochimica et Cosmochimica Acta 59 5223-5231. 

Photodissociation of Diiodoethane Hydrodynamics of Laser-Heated Liquids Gold Nanoparticles in Water... 

Filming of atomic motions in liquids was thus accomplished. More specifically, the above experiment provides atom-atom distribution functions gpv(F, t) as they change during a chemical reaction. It also permits one to monitor temporal variations in the mean density of laser-heated solutions. Finally, it shows that motions of reactive and solvent molecules are strongly correlated the solvent is not an inert medium hosting the reaction [58]. 

C. Rischel, A. Rousse, 1. Uschmann, P. A. Albouy, J.-P. Geindre, P. Audebert, J.-C. Gauthier, E. Froster, J.-L. Martin, and A. Antonetti, Femtosecond time-resolved X-ray diffraction from laser-heated organic films. Nature 390, 490 92 (1997). 

The laser we use in these experiments is an exclmer laser with a pulse width of approximately 20 nsec. In this time regime the laser heating can be treated using the differential equation for heat flow with a well defined value for the thermal diffusivity (k) and the thermal conductivity (K) (4). 

Desorption Rates. Using the above model for the temperature jump associated with pulsed laser heating, the rate of desorption versus time and the total number of molecules desorbed from a finite surface area heated by the laser can be calculated. For the particular case of first-order desorption kinetics, the desorption rate is ... 

Turgor pressure of single leaf cells was measured by an improved version of the cell pressure probe according to Husken et al. (7). Mikrocapillaries were pulled on a laser heated pulling device. 

Climent V, Coles BA, Compton RG. 2002b. Coulostatic potential transients induced by laser heating of a Pt(lll) single-crystal electrode in aqueous acid solutions. Rate of hydrogen adsorption and potential of maximum entropy. J Phys Chem B 106 5988-5996. 

Temperatures as high as 2,500 K have been achieved by laser heating (LH). For such LHDAC experiments, the sample size was around 50-100 pm, the laser beam was focused to about 40 pm, and the synchrotron beam was microfocused to about 10 pm in diameter [70]. The photon-flux for the 14.4 keV ( Fe) synchrotron radiation at the focusing spot was about 10 photons s with a 1 meV energy bandwidth. This flux was reduced by a 5 mm path through diamond, via photo absorption, to 25% of its original value. For comparison the flux of the 21.5 keV radiation of Eu would be reduced to only 60%. 

A number of terms in this area will be unfamiliar to most chemists. Cavitation is the formation of gas bubbles in a liquid and occurs when the pressure within the liquid drops significantly below the vapor pressure of the liquid. Cavitation can occur from a variety of causes turbulent flow, laser heating, electrical discharge, boiling, radiolysis, or acoustic irradiation. We will be concerned... 

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