Laser-induced emission

R. E. Honig and J. R. Woolston. Laser-Induced Emission of Electrons, Ions, and Neutral Atoms from Solid Surfaces. Appl. Phys. Lett., 2(1963) 138-139. 

Figure 15 Laser-induced emission spectra of polymer 3 before (solid line) and after (dashed line) a one second exposure to DNT vapor.

Vander Wal, R. L., K. A. Jensen, and M. Y. Choi, Simultaneous Laser-Induced Emission of Soot and Polycyclic Aromatic Hydrocarbons within a Gas-Jet Diffusion Flame, Combust. Flame, 109, 399-414 (1997). 

Laser techniques can be used to produce extreme temperatures for short durations, possibly as high as several thousand degrees centigrade. Honig and Woolston described a combined laser mass spectrographic technique to study laser-induced emission from solids (3). 

This volume of the Handbook illustrates the rich variety of topics covered by rare earth science. Three chapters are devoted to the description of solid state compounds skutteru-dites (Chapter 211), rare earth-antimony systems (Chapter 212), and rare earth-manganese perovskites (Chapter 214). Two other reviews deal with solid state properties one contribution includes information on existing thermodynamic data of lanthanide trihalides (Chapter 213) while the other one describes optical properties of rare earth compounds under pressure (Chapter 217). Finally, two chapters focus on solution chemistry. The state of the art in unraveling solution structure of lanthanide-containing coordination compounds by paramagnetic nuclear magnetic resonance is outlined in Chapter 215. The potential of time-resolved, laser-induced emission spectroscopy for the analysis of lanthanide and actinide solutions is presented and critically discussed in Chapter 216. 

I. BiUard, HRE, 2003, 33, 465 (time-resolved, laser-induced emission spectroscopy). 

Laser induced emission techniques with sensitivity to mass concentrations down to 0.5 ppb have been used. They are based on the measurement of the laser induced fluorescence and incandescence from the particles. 

Honig, R.E., Woolston, J.R. (1963) Laser-induced emission of electrons, ions, and neutral atoms from sohd surfaces. Appl. Phys. Lett., 2,138. 

Other spectrometry technologies include sliding spark (AGR and the University of Duisberg, Germany), identifying a wide range of plastics and additives, and laser-induced emission (LIESA), by Krupp, the University of Kaiserslautern, and BASF Magnetics. 

Laser-induced emission spectroscopy analysis (LIESA) is a similar technology, in which a beam of laser light is directed onto the surface of the specimen. This induces a short-lived hot plasma that comprises free electrons, excited atoms, and ions of very high electric charge. 

In spite of these considerations MIR proved to be by far the most effective of a range of techniques studied in a wide ranging assessment of recognition methods that also considered NIR, FT Raman spectroscopy. Pyrolysis Mass Spectrometry, Pyrolysis Infrared Spectroscopy and Laser Induced Emission Spectral analysis [6]. 

Laser induced emission is a rapid non-contact method [9],that is extremely useful in identifying heteroatoms present in additives in polymers. 

Lorentzen, C.J., Carlhoff, C., Hahn, U., Jogwich, M. (1992) Applications of laser induced emission spectral analysis for industrial process and quality control. Journal of Analytical Atomic Spectroscopy,... 

Principles and Characteristics The analytical capabilities of the conventional fluorescence (CF) technique (c/r. Chp. 1.4.2) are enhanced by the use of lasers as excitation sources. These allow precise activation of fluorophores with finely tuned laser-induced emission. The laser provides a very selective means of populating excited states and the study of the spectra of radiation emitted as these states decay is generally known as laser-induced fluorescence (LIF, either atomic or molecular fluorescence) [105] or laser-excited atomic fluorescence spectrometry (LEAFS). In LIF an absorption spectrum is obtained by measuring the excitation spectrum for creating fluorescing excited state... 

Principles and Characteristics Simultaneous multi-element analysis based on emission from a plasma generated by focussing a powerful laser beam on a sample (solid, liquid, or gas) is known as laser-induced breakdown spectroscopy (LIBS) and under a variety of semantic variations time-resolved LIBS (TRELIBS), laser ablation emission spectroscopy (LAES), laser ablation atomic emission spectrometry (LA-AES), laser ablation optical emission spectrometry (LA-OES), laser plasma emission spectrometry (L-PES), laser-induced plasma spectroscopy (LIPS), laser spark spectroscopy (LSS), and laser-induced emission spectral analysis (LIESA ). Commercial LIBS analysers were already available in the 60/70s the technique now enjoys a renaissance. 

The inherent complexities of LIBS make it one of the most frustrating of all atomic reservoirs. The following experimental conditions and parameters are best suited to laser-induced emission spectral analysis (i) argon as a buffer gas at reduced pressure (140 hPa) (ii) reduced laser irradiance (Hi) long delay times (>30 /xs) between laser pulse and detector gate pulse and (iv) use of analyte and reference spectral lines with comparable excitation energies [127]. 

LAMMA Laser microprobe mass analysis LIESA Laser-induced emission spectral... 

There are other spectroscopic techniques that could find utility in the recycling industry. Laser acoustic, laser-induced emission spectral analysis, plasma emission spectroscopy, polarized light, phase contrast illumination, UV light, and fluorescent tagging have all been reported [27]. 

The laser-induced emission experiments for BZP/C12- 1500/H20 also showed a special emission of BZP in the nanosecond time scale, very similar to the one reported in [20, Figure 3(b)] for BZP on MCM-41. This emission peaks at ca. 430 nm, and therefore it originates from hydrogenbonded BZP (data not shown). In the case of the BZP/C12- 1700/EtOH sample, no hydrogen-bonded BZP emission in the nanosecond time scale could be detected. 

The RELMA method is a laser induced emission spectral analysis, which is applicable as an instrament for quality assurance in the rubber mixing room. With the RELMA technique, relative element concentrations and their distribution can be determined in a macroscopic scale in usual cycle times of internal mixers. Therefore, quality statements about the compound or even end products can be drawn very fast. Within this paper the optimised RELMA method will be presented and some examples for the application will be shown. In the second part of the application, the RELMA method as a quality assurance instrament for liquids (plasticisers) and disperse solids (carbon black) will be described. 11 refs. 

A wide range of spectroscopic techniques can be used with low-temperature matrices, and fairly routine spectrometers will usually suffice. Nevertheless, NMR spectroscopy is, for aU practical purposes, unavailable. A few research groups have developed special forms of NMR for matrices, but the solid-state spectra obtained are of low resolution, lacking the coupling information that makes conventional NMR in liquids such a powerful structural tool. Usually, matrix chemists make do with IR and UV-visible spectroscopy, supplemented where appropriate with less common techniques such as Raman spectroscopy, laser-induced emission, and EPR. 

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