Phosphor systems

The storage phosphor system was a design prototype developed by AGFA. It consisted of the following components ... 

Some of the conditions to be satisfied by phosphor material are (i) the phosphor should absorb at the emission wavelength of the diode, (ii) the quantum yield should be high and (iii) the full width at half maximum of the emission band should be small to achieve high luminous output. Some of the promising phosphor systems containing Eu3+ and Tb3+... 

Figure 1. Radiochromatograms obtained using TLC a) 2lIAt distribution after oxidation and subsequent reduction of astatine in the absence of closo-dodecaborate and sodium iodide b) 2,1 At distribution after oxidation and subsequent reduction of astatine in the absence of closo-dodecaborate c) 2"At distribution after oxidation and subsequent reduction of astatine in the presence of closo-dodecaborate. d) Spontaneous labelling closo-dodecaborate in the absence of oxidising agent Sodium iodide carrier was added to the reaction mixture before analysis in samples b) c) and d). Merck silica gel 60F 254 TLC aluminium sheets were used and the eluent was acetone/0.1 M ammonia (9/1, v/v). The TLC strips (15x140 mm, elution path 120 mm) were measured on the Cyclone Storage Phosphor System and analysed on the OptiQuant Image Analysis Software.

A quantitative determination of fluorescence intensity as a function of cycling temperature is more complex. It was decided to use a ratio of 0.2 (20%) of the maximum emission intensity as the criteria to determine the viability of fluorescence for a given TSP sample. If the fluorescence emission is small, it will be difficult to measure the decay time and obtain a corresponding surface temperature. There will come a point in intensity where a phosphor system cannot be used to measure temperature. The decision ratio of 0.2 was completely arbitrary and was based on the observation that the apparent fluorescence measurement uncertainty was about 10% (intensity fraction of 0.1), which was two times the measured error for the 611 nm line for Y2O3 Eu. 

Manges, W.W. Allison, S.W. Vehec, J.R. Galvanneal thermometry with a thermographic phosphor system. Iron Steel Engineer 1997, 74 (12), 33-36. 

A two-input INHIBIT gate can be as simple as a receptor-phosphor system. With their inherent sensitivity to molecular oxygen, these systems can be... 

It is easily seen that while the CaW04 W phosphor has its maximum efficiency of emission close to room temperature, the BaW04 W is most efficient close to liquid nitrogen temperature. Therefore, the former is nearly inert at the temperature of maximum emission of the latter and vice-versa. This phenomenon is quite common for many phosphor systems, particularly the self-activated ones. 

The lamp has an internal gas-fill pressure of about 1 -2 mm pressure and contains a mixture of Ne, A, and Kr gases. The internal radiation generated is mostly (85%) 2537 A, which is the resonamce wavelength of the mercury vapor discharge. The other 15% is distributed between 1850 A, 3150 A, 3650 A, 4300 A, 5460 A, and 5785 A. The general phosphor system used has the apatite structure with the general composition ... 

Robbins M (1983) The collectors book of fluorescent minerals. Van Nostrand Reinhold, New York Robbins M (1994) Fluorescence Gems and Minerals Under Ultraviolet Light. Geoscience Press, Phoenix Roeder PL, MacArthur D, Ma X-P, Palmer GR, Mariano AN (1987) Cathodoluminescence and microprobe study of rare-earth elements in apatite. Am Mineral 72 801-811 Ronsbo JG (1989) Coupled substitutions involving REEs and Na and Si in apatites in alkaline rocks from the Ilimaussaq intrusion, South Greenland, and the petrological implications. Am Mineral 74 896-901 Ropp RC (1971) The emission colors of the strontium apatite phosphor system. J Electrochem Soc 118 1510-1512... 

Fig. 4.7. Temperature dependence of the luminescence quantum efficiency (q) according to calculations on a model phosphor system. In (a) the eneigy difference between the parabola minima (Ezp) is varied (values in cm ). In b) the vibrational frequency is varied (values in cm ). In (c) the parabola offset (AR) varies it decreases from left to right 6%...

In (La,Ce)P04 the Stokes shift of the emission is smaller 60(X) cm ), and the emi.sston of CeP04 is partly concentration quenched. Energy migration over the Ce ions assists in the transfer to iV and less Tb is needed. Nevertheless the UV output is relatively high (see Table 6.1). This is due to the fact that the Ce -Ce transfer is more efficient than the Ce +-Tb + transfer. At the shortest intemuclear rare-earth distance the transfer rates amount to 10"s and 3 x lO s, respectively. This phosphor system has been discussed at length recently [21]. 

A new class of phosphors based on ceramic materials has been introduced by several groups [26,27]. These materials are derivatives of the well-known lare-eaith phosphor systems of oxides and oxysulfides. The most promising ceramic host lattices are (Y,Gd)203, Gd202S and Gd3Ga50 2. 

A photostimulable phosphor system for digital mammography was originally introduced commercially by Fuji Film. Several other PSP systems are now available and these are listed in Table 2.2. The dels are of a nominal size of 50 pm. 

Fig. 2.12. Photostimulable phosphor system (a) mechanism of the PSP, (b) double-side d readout to increase efficiency (from Digital Mammography, eds. ED Pisano, MJ Yaffe, CM Kuzmiac. Lippincott, Williams and Wilkins, a Walters Kluwer Company, 2004. Used with permission)...

To increase sensitivity and improve SNR, some photostimulable phosphor system manufacturers have refined their plate technology to reduce laser scattering and increased the efficiency of light collection by reading from both the top and bottom surfaces of the phosphor plate (Fig. 2.12b). 

In photostimulable phosphor systems, the spread of Ught from its point of emission does not affect spatial resolution. The spatial localization is determined initially by the size of the laser spot that is used to read out the signal. As the laser Ught travels through the phosphor, it causes electrons trapped in the phosphor during the X-ray exposure to be freed from the traps. Some of these tiien produce Ught The emitted Ught is collected by an optical system and a photodetector (Fig. 2.17a). 

Rag] Raghavan, V., The C-Fe-P (Carbon-Iron-Phosphorous) System , Phase Diagrams of Ternary Iron Alloys. Part 3 Ternary Systems Containing Iron and Phosphorous, Indian Institute of Metals, 3, 33-44 (1988) (Phase Diagram, Phase Relations, Review, 22)... 

In this chapter, we will first summarize the binary oxyhalide phosphors represented by Sr40Cl6 Eu phosphor then the main topic is focused on the ternary oxyhalide-based phosphors such as halo-silicate phosphors, halo-phosphate phosphors, halo-borate phosphors, halo-aluminate phosphors, and other oxyhalide-based phosphors systems. Finally, we sum up the representative work on crystal-structure and luminescence-property studies for the oxyhalide-based phosphors in oiu group. 

First, the exploration of the oxyhalide phosphors expands the phase spaces to include oxyhalide hosts, thus offering additional opportunities for new phosphor materials. The crystal chemistry study verified that the lower electronegativity of cr versus F leads to lower energy 4/ —> Aj 5d transitions through a larger Sd centroid shift, which will help in discovering some new phosphor systems. The appearance of the new phase, such asBaaPsNioBr, will further enrich such a system. 

Xia Z, Liu J, Li Q, Sun J (2007) Comparative Investigation of Photoluminescence and Long-Lasting Phosphorescence Properties in the (Ca0-CaBr2-Si02) Eu Phosphor System. Electrochem Solid State Lett 10 J4... 

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