Temperature laser-induced

Hg.8. Schematic layout of high temperature laser-induced photoacoustic spectroscopy (R S reference and sample cells, PM power meter, PA preamplifier, and DA differential amplifier) [20]... 

A good example of room temperature laser induced phosphorescence is presented in Figure 4. 

Research has led to alloys which undergo laser-induced crystallization within about 50 ns. This is possible, for example, with TeGe alloys, which also possess the necessary temperature stability up to 180°C and exhibit sufficient reflection (crystalline phase) and transmission characteristics (amorphous phase), respectively. TeGe alloys have not found a practical use because of the formation of depressions in the memory layer typical for them after repeated... 

Figure 4. Experimental laser-induced fluorescence, upper plot, and calculated spectra, lower plot, of the linear He P Cl feature in the ICl B—X, 3-0 region. An P Cl(X,v" = 0) rotational temperature of 0.19 K was measured for the experimental spectrum, and a temperature of 0.20 K was used in the calculations. Adapted from Ref. [51].

Laser-Induced Temperature Jumps and Molecular Desorption... 

The objective of the present work was to determine the influence of the light intensity on the polymerization kinetics and on the temperature profile of acrylate and vinyl ether monomers exposed to UV radiation as thin films, as well as the effect of the sample initial temperature on the polymerization rate and final degree of cure. For this purpose, a new method has been developed, based on real-time infrared (RTIR) spectroscopy 14, which permits to monitor in-situ the temperature of thin films undergoing high-speed photopolymerization, without introducing any additive in the UV-curable formulation 15. This technique proved particularly well suited to addressing the issue of thermal runaway which was recently considered to occur in laser-induced polymerization of divinyl ethers 13>16. 

The photolysis of methyl nitrite at low temperature in an argon matrix was studied157. The products include formaldehyde, and nitroxyl HNO which also reacts to form N2O and water. The 355-nm photodissociation of gaseous methyl nitrite has been studied by monitoring the nascent NO product using a two-photon laser-induced fluorescence... 

The synthesis of a new near-infrared cyanine dye was monitored by CE and fluorescence detection. The chemicals structure of the dye and its synthetic precursor are depicted in Fig. 3.165. The analysis of the dye was realized in fused-silica capillaries of 75 and 100 /an i.d. The total and effective lengths of capillaries were 75 and 60 cm, respectively. The separation voltage was 30 kV and separations were carried out at ambient temperature. The running buffer was 2.5 mM Na2B407 (pH = 9.2). A near-infrared laser-induced fluorescence detector was applied. Electropherograms illustrating the separation of the dye are shown in Fig. 3.166. 

A. R. Bugos, S. W. Allison, and M. R. Cates, Laser-induced fluorescent properties of europium-doped scandium orthophosphate phosphors for high-temperature sensing applications, Proc. of IEEE 1991 Southeast Conf, 1143-1147 (1991). 

Unfortunately, some of the analyzed molecules, as most biologically related molecules (e.g., amino acids), are solids with extremely low vapor pressures at room temperature and rapidly decompose when they are heated. For these molecules, which cannot be thermally vaporized, laser ablation or desorption have been alternatively used to produce neutral species in the gas phase.Both methodologies refer to laser-induced particle removal (laser sputtering) from a surface under the two extremes of massive and negligible rates of surface erosion, respectively. 

Fig. 4. Laser-induced nuorescence detected TPD for NO/Pt(l 11) for 0 , = 0.40 (saturation coverage). NO(i = 0 F, J = 4.S, n(A ) , s=40cm ) was probed. The instantaneous rotational temperatures obtained for 20 K intervals in are plotted against 7. The solid line corresponds to full rotational accommodation, Tf = Tj.

Laser-induced desorption can be utilized quantitatively to remove adsorbates in a localized area of a surface, without substantially altering the temperature of the surrounding sample. This provides a viable technique for measuring surface diffusion kinetics . Alternatively, sampling different... 

Fig, 7. Laser-induced heating model. The solid line represents the temperature transient calculated from Eq. (3) for a S ns FWHM laser pulse (dott trace). The instantaneous desorption rate calculated from Eq. (4) is represented by the... 

A simple model for the dynamics of nonresonant laser-induced desorption of adsorbates from surfaces has been formulated by Lucchese and Tully (LT). LT present the result of stochastic, classical trajectory calculations for thermal and laser-induced desorption of NO from LiF(100). For the LID simulations the initial temperature was set at 0 K and temperature Jumps of several thousand degrees were driven in a few picoseconds through nonspecific heating of the substrate. The interaction potential for these calculations... 

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