Storage phosphors

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

Compounds that are radioactive can be located on a preparative layer by contact film autoradiography, electronic autoradiography, and storage phosphor screen imaging [21-23]. These methods differ in terms of factors such as simplicity, speed, sensitivity, and resolution, and the method of choice depends on the available equipment, reagents, and instrumentation. All are nondestructive, and the detected compounds can be recovered without change for later studies. 

Image plates use stimulated luminescence from storage phosphor materials. The commercially available plates are composed of extremely fine crystals of BaFBrEu2+. X-rays excite an electron of Eu2+ into the conduction band, where it is trapped in an F-center of the barium halide with a subsequent oxidation of Eu2+ to Eu3+. By exposing the BaFBrEu" complex to light from a HeNe laser the electrons are liberated with the emission of a photon at 390 nm [38]. 

Laser devices are the most sophisticated image-acquisition tools. They are particularly useful for gels labeled with fluorescent dyes because the lasers can be matched to the excitation wavelengths of the fluorophores. Detection is generally with photomultiplier tubes. Some instruments incorporate storage phosphor screens for detection of radiolabeled and chemiluminescent compounds (not discussed in this chapter). Resolution depends on the scanning speed of the illumination module and can be as low as 10 pm. 

A Storage Phosphor Detector (bnaging Plate) and its Application to Diffraction Studies Using Synchrotron Radiation... 

Amemiya, Y., Satow, Y., Matsushita, T., Chikawa, J., Wakabayashi, K., and Miyahara, J. A Storage Phosphor Detector (Imaging Plate) and Its Application to Diffraction Studies Using Synchrotron Radiation. 147,121-144 (1988). 

The production of such storage phosphors is carried out by the method described for BaFCl Eu2+. These phosphors are used for storage panels in X-ray diagnostics (see Section 5.5.4.2). 

Storage phosphors include Y202S Eu3+, Bi3 + GdOBr Sm3 + LaOBr Tb3 +, Bi3 + and the barium fluorohalides. 

The species to be compared are loaded in 6% Ficoll (w/v) onto an 8% or 10% polyacrylamide gel with 29 1 monomer bisacrylamide. We generally use 90 mM Tris—borate (pH 8.3) buffer containing either EDTA or added metal salts. Electrophoresis is typically performed for 1—2 days at 5 V/cm at room temperature. When salts are included in the electrophoresis buffer, this must be recirculated between the cathodic and anodic reservoirs at a rate of 1 L/h. This may require a little modification of commercial gel electrophoresis apparatus. Our RNA species generally include at least one strand that is radioactively [5/-32P] -labeled. When the electrophoresis is complete the gel is dried onto Whatman 3MM paper and exposed to storage phosphor plates at 4 °C followed by phosphorimaging to provide a gel image. 

Autoradiography Using Storage Phosphor Technology. Electrophoresis 11 355. 

Energy storage phosphors are materials in which an irradiation induces ionization of some ions followed by capture of the extracted electrons by vacancies, forming colour centres, or oxidizing cations. By irradiation in the absorption bands of the centres so created (photostimulation) or temperature rise, the trapped electrons can be released and the recombination energy with holes transferred to a luminescent ion. 

Barker D. L. (1990). Autoradiography using storage phosphor technology. Electrophoresis 11, 355-360. 

W. Chen, Luminescence, Storage Mechanisms, and Apphcations of R-ray Storage Phosphors, in Handbook of Luminescence, Display Materials and Devices , eds. H. S. Nalwa and L. S. Rohwer, ASP, 2003, Vol. 2,... 

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.

The barium fluorohalides BaFCl and BaFBr are of practical interest as matrices for X-ray storage phosphors. The Ba NMR spectra of both compounds have been reported and their NMR interaction parameters determined (B as tow and Stuart 1996). The room temperature xq value of BaFCl is relatively small but increases rapidly with temperature, possibly due to variations in the thermally averaged structure about the Ba nucleus. The room temperature xq value of BaFBr is larger by a factor of 10 than that of BaFCl, and its Ba linewidth was such that the spectrum had to be determined by the stepped-frequency method, by contrast with the static BaFCl spectrum which was sufficiently narrow that the whole transition could be excited by ordinary pulse spectroscopy (Bastow and Stuart 1996). 

BaFBr is an important storage phosphor material which forms solid solutions and gives rise to nonstoichiometric compositions such as (BaF)i iBro.g. The principal F MAS NMR resonance in BaFBr occurs at 150.9 ppm but the non-stoichiometric sample shows an additional line at 145.3 ppm with an intensity of 9%. The similarity of this intensity to the 10% excess fluorine in the sample led to the assignment of this resonance to fluorine on the antisites (the bromine sites) (Schweizer etal. 1998). 

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