Laser technique

Miller R E 1995 Near-Infrared laser optothermal techniques Laser Techniques in Chemistry 23, ed A B Myers and T R Rizzo (New York Wiley) pp 43-69... 

Kohse-Hdinghaus K 1994 Laser techniques for the quantitative detection of reactive intermediates in combustion systems Proc. Energy Combust. Sc/. 20 203-79... 

Bernstein R B (ed) 1982 Chemical dynamics via molecular beam and laser techniques The Hinshelwood Lectures (Oxford, 1980) (Oxford Oxford University Press)... 

In Section 9.2.2 we saw that a pulsed Tp sapphire laser can produce pulses less then 10 fs in length. There are also other laser techniques which can be used to produce pulse lengths... 

Scaiano and Kim-Thuan (1983) searched without success for the electronic spectrum of the phenyl cation using laser techniques. Ambroz et al. (1980) photolysed solutions of three arenediazonium salts in a glass matrix of 3 M LiCl in 1 1 (v/v) water/acetone at 77 K. With 2,4,5-trimethoxybenzenediazonium hexafluorophos-phate Ambroz et al. observed two relatively weak absorption bands at 415 and 442 nm (no e-values given) and a reduction in the intensity of the 370 nm band of the diazonium ion. The absence of any ESR signals indicates that these new bands are not due to aryl radicals, but to the aryl cation in its triplet ground state. 

In order to further extend the utility of fluorescence methods the use of time-resolution methods, fluorescence polarization, and laser techniques should be explored. The addition of other dyes with enhanced fluorescence properties on binding and increased selectivity to various types of nucleic acids will be necessary to further develop more useful analytical methods. 

Up to the present, a number of conventional film preparation methods like PVD, CVD, electro-chemical deposition, etc., have been reported to be used in synthesis of CNx films. Muhl et al. [57] reviewed the works performed worldwide, before the year 1998, on the methods and results of preparing carbon nitride hlms. They divided the preparation techniques into several sections including atmospheric-pressure chemical processes, ion-beam deposition, laser techniques, chemical vapor deposition, and reactive sputtering [57]. The methods used in succeeding research work basically did not... 

Smyth, K.C. and Crosley, D.R., Detection of minor species with laser techniques, in Applied Combustion Diagnostics, Kohse-Hoinghaus, K. and Jeffries, J.B. (Eds.), Taylor Francis, New York, 2002, Chapter 2. 

Temporal sequence of OH-LIF measurements captures a localized extinction event in a turbulent nonpremixed CH4/H2/N2 jet flame (Re 20,000) as a vortex perturbs the reaction zone. The time between frames is 125 ps. The velocity field from PIV measurements is superimposed on the second frame and has the mean vertical velocity of 9m/s subtracted. (From Hult, J. et al.. Paper No. 26-2, in 10th International Symposium on Applications of Laser Techniques to Fluid Mechanics, Lisbon, 2000. With permission.)... 

This chapter discusses the apphcation of femtosecond lasers to the study of the dynamics of molecular motion, and attempts to portray how a synergic combination of theory and experiment enables the interaction of matter with extremely short bursts of light, and the ultrafast processes that subsequently occur, to be understood in terms of fundamental quantum theory. This is illustrated through consideration of a hierarchy of laser-induced events in molecules in the gas phase and in clusters. A speculative conclusion forecasts developments in new laser techniques, highlighting how the exploitation of ever shorter laser pulses would permit the study and possible manipulation of the nuclear and electronic dynamics in molecules. 

The vibrational spectrum of a metal complex is one of the most convenient and unambigious methods of characterization. However, it has not been possible to study the interactions of metal ions and biological polymers in this way since the number of vibrational bands from the polymer obscure the metal spectrum. The use of laser techniques for Raman spectroscopy now make it very likely that the Raman spectra of metals in the presence of large amounts of biological material will be measured (34). The intensity of Raman lines from metal-ligand vibrations can be... 

The historical development and elementary operating principles of lasers are briefly summarized. An overview of the characteristics and capabilities of various lasers is provided. Selected applications of lasers to spectroscopic and dynamical problems in chemistry, as well as the role of lasers as effectors of chemical reactivity, are discussed. Studies from these laboratories concerning time-resolved resonance Raman spectroscopy of electronically excited states of metal polypyridine complexes are presented, exemplifying applications of modern laser techniques to problems in inorganic chemistry. 

The following case study contains examples of several topics discussed in previous sections, including some aspects of laser technology, laser spectroscopy and laser chemistry. A variety of lasers and laser techniques are applied in a straightforward manner to the problem of ascertaining structural and dynamical information on an excited electronic state of wide chemical interest. This information is obtained rather simply, illustrating the potential of laser techniques in the resolution of problems in solution chemistry. 

Diphenylmethylene was the first carbene to be studied using fast, time-resolved spectroscopic methods (Closs and Rabinow, 1976). Since then both nanosecond and picosecond laser techniques have been used to probe this intermediate (Eisenthal et al., 1980, 1984 Hadel et al., 1984a,b Griller et al., 1984b Langan et al., 1984 Sitzmann et al., 1984). The results of these experiments are essentially undisputed, but the interpretation of them still remains somewhat controversial. 

Omrane, A. Santesson, S. Alden, M. Nilsson, S., Laser techniques in acoustically levitated micro droplets, Lab. Chip. 2004, 4, 287 291... 

In addition to the techniques outlined above, many other methods have been developed for droplet sizing. These include, for example, intensity ratio method, phase optical-microwave method, and dual-cylindrical wave laser technique)1(n etc. 

It is now possible to design the experiments using molecular beams and laser techniques such that the initial vibrational, rotational, translational or electronic states of the reagent are selected or final states of products are specified. In contrast to the measurement of overall rate constants in a bulk kinetics experiment, state-to-state differential and integral cross sections can be measured for different initial states of reactants and final states of products in these sophisticated experiments. Molecular beam studies have become more common, lasers have been used to excite the reagent molecules and it has become possible to detect the product molecules by laser-induced fluorescence . These experimental studies have put forward a dramatic change in experimental study of chemical reactions at the molecular level and has culminated in what is now called state-to-state chemistry. 

Bernstein, R.B. (ed) (a) Chemical Dynamics via Molecular Beam and Laser Techniques, Clarendon Press, Oxford, New York (1982). (b) Atom-Molecule Collision Theory A guide to experimentalist, Plenum Press, New York (1979). 

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