Analytical Laser Spectroscopy Research Articles

Nanoparticles in analytical laser and plasma spectroscopy – a review of recent developments in methodology and applications

There is a mutually supportive relationship between materials science (nanoparticles) and analytical laser/plasma spectroscopy.

Recent Developments of Analytical Laser Spectroscopy Investigated through an Analysis of Patent Applications

Patent applications submitted between Jan. 1 of 1982 and Dec. 31 of 2005 and published before Oct. 4 of 2007 have been analyzed to investigate recent developments of analytical laser spectroscopy. Out of 9892 patent publications found through keyword searches, 658 patent applications have been concluded to be relevant. Major laser techniques are fluorescence, absorption, emission, Raman and photoacoustic. Fluorecences pectroscopy has the largest contribution. Absorption and emission spectroscopy follow. The peak in the number of applications occurs around 1996, but a recent increase is remarkable especially among foreign applicants. The difference between domestic applicants and foreign applicants lies largely in fluorescence spectrosopy, especially in its biological applications. If analytical laser spectroscopy is going to be useful for the diagonolysis of disease, this report suggests a need for extended research in this field in Japan.

Application of frustrated total internal reflection devices to analytical laser spectroscopy.

Novel implementations of single-fiber laser-induced breakdown spectroscopy and laser-induced fluorescence spectroscopy systems that gated light switches based on frustrated total internal reflection are described. The switching devices are largely wavelength independent, with full temporal and spatial separation of laser and fluorescence light. Wavelength-independent beam separation or beam combination schemes can be implemented for coaxial optical setups, e.g., in single-fiber or telescopic experimental arrangements. Selected practical examples of schemes for qualitative and quantitative analytical spectroscopy are discussed.

Cancellation of Matrix Effects and Calibration by Isotope Dilution in Isotope-Selective Diode Laser Atomic Absorption Spectrometry

High-resolution atomic absorption measurements of lead isotopes are performed in a graphite tube atomizer with integrated low-pressure dc discharge using frequency-doubled laser diode radiation at 405.78 nm. For the first time, calibration by isotope dilution is demonstrated in analytical laser spectroscopy. Furthermore, isotope dilution is proved to be an effective technique for cancellation of chemical as well as physical matrix effects in optical spectrochemistry.

Laser spectroscopy on organic molecules.

Various laser spectrometric methods have been developed until now. Especially, laser fluorometry is most sensitive and is frequently combined with a separation technique such as capillary electrophoresis. For non-fluorescent compounds, photothermal spectrometry may be used instead. A diode laser is potentially useful for practical trace analysis, because of its low cost and long-term trouble-free operation. On the other hand, monochromaticity of the laser is essential in high-resolution spectrometry, e.g. in low temperature spectrometry providing a very sharp spectral feature. Closely-related compounds such as isomers can easily be differentiated, and information for assignment is obtained from the spectrum. Multiphoton ionization mass spectrometry is useful for soft ionization, providing additional information concerned with molecular weight and chemical structure. A short laser pulse with a sufficient energy is suitable for rapid heating of the solid surface. A matrix-assisted laser desorption/ion-ization technique is recently employed for introduction of a large biological molecule into a vacuum for mass analysis. In the future, laser spectrometry will be developed by a combination with state-of-the-art laser technology. In the 21st century, new laser spectrometry will be developed, which may be based on revolutionary ideas or unexpected discoveries. Such studies will open new frontiers in analytical laser spectroscopy.

Detection of trace concentrations of elements by intra-cavity frequency- dispersion laser atomic spectroscopy

A new method of analytical laser spectroscopy is suggested. It is based on transformation of resonance linear dispersion of absorbing atoms inside the cavity of a two-mode laser with homogeneous super-broad gain profile into mode beats frequency variation. The detection sensitivity with respect to absorption in the probing volume as high as 10 10 Hz cm −1 has been achieved. This value is in excellent agreement with the theoretical prediction. A sensitivity of about 10 12 Hz ( g ml ) −1 has been demonstrated in experiments with aqueous sodium standards. The experimentally achieved limit of detection of approximately 10 ng ml −1 was limited by the purity of the distilled water. It has been estimated by extrapolation that a limit of detection of the order of 0.1–1.0 pg ml −1 can be achieved when using ultrapure water and registering beats frequency shifts of the order of 1 Hz. The method is shown to be independent of intensity and stationary lasing time.

Theoretical considerations of laser induced fluorescence and ionization spectrometry: how close to single atom detection

The potential capability of detecting single atoms and/or of approaching the intrinsic detection limit, i.e. the limit where all external causes of noise in the system are eliminated, is discussed with respect to laser induced fluorescence and ionization spectrometry. These approaches have been chosen because of their widespread use in laboratories involved in analytical laser spectroscopy. Among the lasers, tunable dye lasers pumped by N 2, Nd-YAG, Excimer, Cu vapor lasers and flashlamps are considered, and flames, graphite furnaces, plasmas and low pressure glow discharges are considered as atom reservoirs. From practical considerations, it is shown that none of the conventional analytical approaches used can satisfy the requirement of a true single atom detection technique, the only exception being provided by the ionization method coupled with atomization under vacuum.

Characteristics of laser applications in precision analytical measurements (review)

Analytical laser spectroscopy is undergoing a great deal of progress and a large number of original and review work is published in which the development of different aspects of analytical laser spectroscopy is discussed (see [2, 82-102]). In practical analytical measurements, nontraditional methods find increasing acceptance based on the well-known physical models of the process of measurement and the indirect relation of the measured values with a standard which reproduces principal units in terms of fundamental, atomic and molecular constants. Development of absolute methods for the measurement of components of materials is a very relevant task when one is concerned with such a small number of probes or with trace concentrations that the making or using of standard gas mixture is practically not feasible. On the other hand, obtaining and saving the given gas mixtures for later use, as usual, introduces significant systematic error especially when we are concerned with unstable and corrosive gaseous components or ultra-microconcentrations. The universal method for the measurement of component concentration in the atmosphere is the direct absorption method. In order to determine the concentration of the component under measurement, it is necessary to know its coefficient of absorption under similar conditions. High sensitivity and accuracy as determined by the accuracy in the measurement of the absorption coefficient may be attained when laser radiation sources with a radiation power stabilization system are used.

Book reviews

Book reviews

Analytical Laser Spectroscopy: Volume 50 in ‘Chemical Analysis’ – a Series of Monographs on Analytical Chemistry and its Applications

N Omenetto (ed) 1979 New York: John Wiley 550 pp price £24.50 This book interprets analytical laser spectroscopy somewhat widely in the context of chemical analysis, and comprises eight chapters contributed by various authors. These are: Basic principles of lasers; Analytical laser spectroscopy using laser atomisers; Atomic absorption spectroscopy with laser primary sources; Atomic fluorescence spectroscopy with laser excitation; Molecular absorption and fluorescence spectroscopy with lasers; Analytical use of lasers in remote sensing; An introduction to signals, noise and measurement; and Recent advances in analytical laser spectroscopy.