Laser Induced Luminescence

Esperite is a calcium lead zinc-silicate mineral. The crystal structure is mono-clinic-prismatic (P21/m) with a B2 jm group. Steady-state laser-induced luminescence of esperite was ascribed to Mn " in Zn and Ca positions, accompanied by Dy " and Sm " lines. Besides that reabsorption lines of Nd " and have been found (Gorobets and Rogojine 2001). The laser-induced time-resolved... 

Fig. 4.47. Laser-induced luminescence spectrum of sUlimanite (Wojtowicz and Lempicki 1988)...

Fig. 4.60. Laser-induced luminescence spectra of eosphorite Vergara et al. (1990)...

Fig. 4.64. Laser-induced luminescence of chlorite with Cr emission (Czaja 1999)...

Neodymium in natural and artificial apatite is characterized by anomalous distribution of luminescence intensity in the groups at 1.06 and 1.3 pm. In each of these spectral groups there is one fine whose intensity exceeds many times the intensity of the remaining fines of said group (Morozov et al. 1970). In laser-induced luminescence of natural apatites we also found somewhat different luminescence spectra (Eig. 4.3). Decay times of these fines are rather close and it is possible to suppose that all Nd occupy the Ca(I) sites with different charge compensations. 

Fig. 5.10. a-d Laser-induced luminescence and excitation spectra of synthetic apatite artificially activated by Eu in vacuum (a) and in air (b)... 

Fig. 5.16. Laser-induced luminescence of barite 1 - after heating at 600 °C while violet luminescence of evidently Eu " appears 2 - after X-ray irradiation of the heated sample where blue shoulder appears, supposedly connected with Eu+ (Gaft and Rudenkova 1993)...

Fig. 5.35. Laser-induced luminescence of artificial apatite activated by Cr ...

Fig. 5.36. a-d Laser-induced luminescence of Mn " in artificially activated (a-c) and natural... 

Fig. 5.46. Polarized laser-induced luminescence of different Mn " centers in apatite...

Fig. 5.48. Laser-induced luminescence of Mn bearing minerals (1-helvine 2-severgenite 3-Mn-mUarite 4-triplite 5-rodonite 6-rhodochrosite 7-Mn-calcite 8-Mn-curchatovite 9- Mn-tantalite 10-dgimboite 11-Mn-apatite) and its connection with crystallochemical structure a-rhodonite fo-rhodochrosite c-Mn-apatite d-carpholite (MnAl2(Si206)(0H)4 (Gaftetal. 1981)...

We studied laser-induced time-resolved lirminescence of synthetic BaS04 artificially activated by Sn and foimd several intensive UV and blue bands evidently connected with Sn emission (Fig. 5.55). Similar bands have been also found in natural barite laser-induced luminescence spectra and we think that their connection with an Sn center is quite possible. 

Figure 4.29 represents a typical laser-induced luminescence spectra recorded from natural barite with orange luminescence. At room temperature imder 308, 337 and 355 nm excitations orange luminescence consists of a very broad band peaking at 635 nm with a half-width of approximately = 150 nm (Fig. 4.29a). At lower temperatures up to liquid hehum the spectriun is very similar and only the half-width of A = 130 nm becomes a httle narrower (Fig. 4.29b). At all temperatures the spectra are not dependent on delay times and gate widths. The possible conclusion is that only one liuninescence center is responsible for this orange band. The decay time of luminescence is approximately 225 ps at 300 K and 275 ps at 4.2 K.

The spectral-kinetic parameters of the green laser-induced luminescence of the sedimentary apatites allow its association with emission. The spectra... 

The spectra of the green laser-induced luminescence represented in Fig. 4.4a, together with their decay time, also allows its association with These luminescence spectra strongly differ from the spectral parameters of all known uranyl minerals. For this reason it is not possible to connect this type of green luminescence with finely dissipated uranyl phases. On the other hand, this luminescence is very similar in such different host minerals as sedimentary apatites, opalites, chalcedony, chert, quartz and barites. Luminescence independence from the minerals structure evidences that it may be connected with uranyl adsorption on the minerals surface, supposedly in the form of (UO2 X nH20)2+. 

Another aspect of minerals and rocks laser-induced luminescence became important recently, especially in Israel. Terrorists have intensively used roadside Ijombs, while the plastic covers simulating local rocks have been used for camouflage of explosive materials. The possibilities of the luminescence method have been checked for the remote detection and identification of such camouflage materials. The luminescence properties of the colored plastics have been investigated in comparison with the corresponding properties of the dolomite rocks, which are imitated. 

La is of interest in its relationship to biological hydroxyapatite because of their inhibitory effect on the demineralization of dental enamel. The form of La was not clear, namely surface adsorption or lattice incorporation. In an attempt to clarify it, laser-induced luminescence has been used (Mayer et al. 1999). La " is not luminescent, Gd-containing samples were prepared and studied. Figure 11.1 demonstrates Gd luminescence spectra with 266 nm laser excitation before and after heating at 800 °C. It is clearly seen that luminescence intensity is drastically stronger after thermal treatment. Thus precipitated samples must be heated to 800 °C to enable Gd " " to replace Ca and become luminescent and its incorporation form is surface adsorption. 

Fig. 11.1. Laser-induced luminescence of Gd in precipitated hydroxyapatite before and after heating at 800 °C...

The Applications of Laser-induced Time-resolved Spectroscopic Techniques chapter starts with a short description of laser-induced spectroscopies, which may be used in combination with laser-induced luminescence, namely Breakdown, Raman and Second Harmonic Generation. The chapter contains several examples of the application of laser-based spectroscopies in remote sensing and radiometric sorting of minerals. The proljlem of minerals as geomaterials for radioactive waste storage is also considered. 

Horrocks, W. de W. Jr. Sudnick, D. R. Lanthanide ion probes of structure in biology. Laser-induced luminescence decay constants provide a direct measure of the number of metal-coordinated water molecules. J. Am. Chem. Soc. 1979,101(2), 334-340. 

Investigation of Adsorption Mechanisms by Laser Induced Luminescence... 

Using benzophenone (BZP) as probing hosts, laser induced luminescence was employed to get a deeper understanding regarding the mechanism involved... 

Fig. 3. Schematic diagram of the laser induced luminescence system.

Chen J, Feng Z, Ying P, Li C (2004) ZnO cluster encapsulated inside micropores of zeohte studied by UV Raman and laser induced luminescence spectroscopies. J Phys Chem B 108 12669... 

Using time resolved laser induced luminescence spectroscopy the relative yields of T-T Intra-ET and S-S Intra-ET were determined. Typical examples are shown in Figs. 3-6 where comparison is made between the relative quantum yields of fluorescence and phosphorescence of the o-diketone chromophore upon direct excitation of the a-diketone chromophore at 430 nm to that obtained by exciting the aromatic moiety at 266nm followed by S-S and T-T Intra-ET. The results indicate competition between T-T Intra-ET and S-S Intra-ET leading to a more efficient T-T process whenever S-S Intra-ET becomes less efficient. 

These results were used also in geosciences, remote sensing, exploration, natural dosimetry, mineral processing etc. Starting from approximately 20 years ago, UV lasers have been used as luminescence of minerals excitation source. By such a way, not only luminescence spectra, but decay times also have been determined. The main motivation was to use laser-induced luminescence for remote sensing of mineral deposits (Kasdan et al. 1981 Seigel and Robbins 1985). Systematical... 

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