Laser fluorescence spectroscopy

After the laser flash, one then monitors the progress of events by some rapidly responding method. Conductivity, absorption spectroscopy, and fluorescence spectroscopy are the methods most commonly used. If a reaction product has a characteristic absorption band of sufficient intensity, one can monitor its buildup with time. This might be a UV, visible, or IR band. The need for a band with a high molar absorptivity arises because the reactive transient is usually present at a relatively low concentration, KT6-lCr5 M being typical. If the species of interest is phosphorescent, then the timed decay of its phosphorescence intensity can be recorded. 

In addition to measuring total recombination coefficients, experimentalists seek to determine absolute or relative yields of specific recombination products by emission spectroscopy, laser induced fluorescence, and optical absorption. In most such measurements, the products suffer many collisions between their creation and detection and nothing can be deduced about their initial translational energies. Limited, but important, information on the kinetic energies of the nascent products can be obtained by examination of the widths of emitted spectral lines and by... 

This agrees quite well with the rate constants for intramolecular proton transfer in 2,4-bis(dimethyl-amino )-6-(2-hydroxy-5-methylphenyl)-5-triazine which had been measured by Shizuka et al. ( l6) using laser picosecond spectroscopy. The fluorescence decay constant t of (TIN) was found to be 60 20 ps. Because of the weak intensity all fluorescence lifetimes refer to the pure substance in crystalline form at room temperature. 

Fig. 7. Potential mechanisms of actinide (represented by Cm(ni)) interaction with colloids as interpreted from laser fluorescence spectroscopy (TRLFS) experiments. Spectra are taken from Stumpf et al. (2001o, b) and Chung et al. (1998).

Chung, K. H., Klenze, R., Park, K. K., Paviet-Hartmann, P. Kim, J. I. 1998. A study of the surface sorption process of Cm(III) on silica by time-resolved laser fluorescence spectroscopy (I). Radiochimica Acta, 82, 215-219. 

Stumpf, Th., Bauer, A., Coppin, F. Kim, J. I. 200]a. Time-resolved laser fluorescence spectroscopy study of the sorption of Cm(III) onto smectite and kaolinite. Environmental Science and Technology, 35, 3691 -3694. 

Stumpf, Th. Fanghanel, Th. 2002. A time-resolved laser fluorescence spectroscopy (TRLFS) study of the interaction of trivalent actinides (Cm(III)) with calcite. Journal of Colloid and Interface Science, 249, 119-122. 

TCLP TDB TDF THC TBP TEM TLM TM-AFM TOC TRLFS TRU TSP TST TVS Toxicity characteristics leaching procedure Thermodynamic database Tyre-derived fuel Total hydrocarbon Tri-n-butyl phosphate Transmission electron microscopy Triple layer model Tapping mode atomic force microscopy Total organic carbon Time-resolved laser fluorescence spectroscopy Transuranic Total suspended particles Transition state theory Transportable vitrification system... 

Some of the most powerful tools for in situ discharge diagnostics are optical (62). Plasma-induced emission spectroscopy, laser-induced fluorescence, laser absorption, and laser optogalvanic spectroscopy have all been... 

Chemical state characterization IR and Raman Spectroscopy, FT-IR, EELS, XPS, SIMS, ESDIAD, ellipsometry, and laser fluorescence... 

Abbreviations AOD, Acousto-optical deflection BCB, bisbenzyocyclobutadiene CCD, indirect contact conductivity detection CL, chemiluminescence ECD, electron capture detector FCS, fluorescence correlation spectroscopy FRET, fluorescence resonance energy transfer ICCD, integrated contact conductivity detection GMR, giant magnetoresistive LED-CFD, light emitting diode confocal fluorescence detector LIF, laser-induced fluorescence LOD, limit of detection MALDI, matrix-assisted laser desorption ionization PDMS, poly(dimethylsiloxane) PMMA, poly(methylmetha-crylate) SPR, surface plasmon resonance SVD, sinusoidal voltammetric detection TLS, thermal lens spectroscopy. 

By contrast, laser scattering methods now permit temperature composition and flow measurements that are both nonintrusive and give very high spatial resolution. These light scattering methods include laser Raman spectroscopy, laser-induced fluorescence, coherent Raman spectroscopy as well as laser velocimetry... 

The measurements of temperature and species concentrations profiles in premixed, laminar flames play a key role in the development of detailed models of hydrocarbon combustion. Systematic comparisons are given here between a recent laminar methane-air flame model and laser measurements of temperature and species concentrations. These results are obtained by both laser Raman spectroscopy and laser fluorescence. These laser probes provide nonintrusive measurements of combustion species for combustion processes that require high spatial resolution. The measurements reported here demonstrate that the comparison between a model and the measured concentrations of CH, O2,... 

Two techniques, which appear well suited to the diagnostic probing of practical flames with good spatial and temporal resolution, are coherent anti-Stokes Raman spectroscopy (CARS) and saturated laser fluorescence. The two techniques are complementary in regard to their measurement capabilities. CARS appears most appropriate for thermometry and major species concentration measurements, saturated laser fluorescence to trace radical concentrations. With electronic resonant enhancement (6), CARS may be potentially useful for the latter as well. Fluorescence thermometry is also possible (7, 8) but generally, is more tedious to use than CARS. In this paper, recent research investi-... 

Optical spectroscopies. These techniques are the least intrusive in situ plasma diagnostic methods. The most commonly used techniques are emission spectroscopy, absorption spectroscopy, laser-induced fluorescence. 

Characterization of collected fractions using spectroscopic techniques Electrochemical detection On-line mass spectrometry and IR spectroscopy Laser-induced fluorescence Photodiode array detectors Radioactivity detectors... 

Laser Fluorescence Spectroscopy of Molecular Molybdenum Isolated in Rare Gas Matrices... 

Kogure T, Karasawa S, Araki T, Saito K, Kinjo M, Miyawaki A. A fluorescent variant of a protein from the stony coral Montipora facilitates dual-color single-laser fluorescence cross-correlation spectroscopy. Nat. Biotechnol. 2006 24 577-581. 

We can now look at single molecules in room temperature solutions and see them by laser fluorescence spectroscopy. We can also capture them with light and move them about. The whole area of single-molecule detection is exciting because it breaks the averaging that you normally get when you look at ensembles. It allows you to see rare events that otherwise get lost in the average over observation of all the members of an ensemble. 

Graphite furnace AAS Atomic fluorescence spectroscopy Inductively-coupled-plasma optical-emission spectroscopy Glow-discharge optical-emission spectroscopy Laser-excited resonance ionization spectroscopy Laser-excited atomic-fluorescence spectroscopy Laser-induced-breakdown spectroscopy Laser-induced photocoustic spectroscopy Resonance-ionization spectroscopy... 

Fig. 2.4. (A) Sketch of the cryostat insert for single-molecule spectroscopy by fluorescence excitation. The focus of lens L is placed in the sample S by the magnet/coil pair M, C. (B) Scan over the inhomogeneous line (a) with a 2 GHz region expanded (b) to show isolated single-molecule absorption profiles. (C) Three-dimensional pseudo-image of single molecules of pentacene in p-terphenyl. The measured fluorescence signal (z-axis) is shown over a range of 300 MHz in excitation frequency (horizontal axis, center = 592.544 nm) and 40 pm in spatial position (axis into the page). (D) Rotation of the data in (c) to show that in the spatial domain, the single molecule maps out the shape of the laser focal spot. Bar, 5 pm. For details, see [33]...

In the last two decades the coordination chemistry of these elements has benefited greatly from advances in time-resolved laser fluorescence (TRLIFS) and synchrotron-based X-ray absorbance spectroscopies (XANES and XAFS). The advantageous luminescence properties of Am and... 

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