Organic Scintillators

The emitted P particles excite the organic molecules which, in returning to normal energy levels, emit light pulses that are detected by a photomultiplier tube, amplified, and electronically counted. Liquid scintillation counting is by far the most widely used technique in tritium tracer studies and has superseded most other analytical techniques for general use (70). 

Fig 1 Quenching of the Scintillation Process by Organic Nitrocompounds in Toluene-14C-PPO... 

Organic Scintillators and Liquid Scintillation Counting , Academic Press, NY (1971)... 

General procedure for Suzuki coupling. 4-Bromoanisole (125 pL, 1 mmol), phenylboronic acid (186 mg, 1.5 mmol), K2CO3 (0.55 g, 4 mmol) and the BaCei.j,Pdj,03.j, catalyst were mixed in a 20 ruL scintillation vial. A preheated 2-propanol/water solution (IPA/H2O, 1 1 v/v, 12 ruL, 80°C) was added, the vial was immediately placed on a hot plate stirrer and its temperature was maintained at (80 1) °C. The reaction mixture was stirred at 1000 rpm for 3 min, then cooled to room temperature. The 4-methoxybiphenyl product was extracted with diethyl ether (3 x 15 ruL). The organic fractions were washed with deionized water and dried with MgS04. After filtration, volatiles were removed under reduced pressure to yield the isolated product. 

Polyacrylamide gels were dissolved in 30% peroxide solution and added to a scintillation mixture in 1 1 2-ethoxy ethanol-toluene. After counting, the mixtures were bulked and evaporated intermittently with heat dining a 4 week period, and the accumulated peroxidised residues eventually exploded violently [1], A subsequent comment indicated that peroxidised materials may not necessarily have been formed, because solutions of organic materials in aqueous peroxide are themselves potentially explosive [2],... 

There are three classes of solid state scintillation phosphors organic crystals, inorganic crystals, and plastic phosphors. 

Organic scintillation phosphors include naphthalene, stilbene, and anthracene. The decay time of this type of phosphor is approximately 10 nanoseconds. This type of crystal is frequently used in the detection of beta particles. 

Concentrations of radiolabeled proteins, substrates, or products can be quantified by scintillation counters, which detect both emitters of weak (e. g., 3H) and high energy (e.g., 32P) by excitation of an organic solvent (e.g., toluene) which then emits fluorescence fight. In commercial systems the primary fluorescence is transformed via one or two additional fluorescent dyes in the solution into a visible emission signal which can easily be detected by conventional photomultipliers. 

Ross HJE, Noakes E, Spalding JD. Liquid Scintillation Counting and Organic Scintillators, Lewis, Chelsea, MI, 1991. 

Figure 5.5 Scintillants. A range of organic scintiilants is available with different solubility and emission characteristics, Scintillant cocktails or mixtures contain a primary scin-tillant such as PPO and often contain a secondary scintillant which absorbs the radiation produced by the primary scintillant and re-emits it at a longer wavelength, e.g, POPOP,...

DDT Metabolism.-- The metabolism of DDT has been studied in R and S fish, following similar protocols to chlorinated cyclodiene metabolism organic extraction (acetonitrile), thin layer chromatography of organic extracts, and liquid scintillation counting of the resultant spots (4). When S and R fish were exposed to 60 yg/l of 14C-labelled , -DDT for 4 hr, radioactivity was found in the spots which co-chromatographed with... 

Both the organic and water layers from the radioactive insecticides were counted in a liquid scintillation counter (Isocap/300, Searle). The results are expressed as nanomoles or micrograms equivalent of the substrate per mg protein. 

Uses Dyes starting material for the preparation of alizarin, phenanthrene, carbazole, 9,10-anthraquinone, 9,10-dihydroanthracene, and insecticides in calico printing as component of smoke screens scintillation counter crystals organic semiconductor research wood preservative. 

Organic media are suitable for detecting and counting radioactivity by scintillation methods, because the quenching of scintillation in organic... 

Other uses are to produce phosphorescence and fluorescence in organic compounds and for scintillation screens on instruments used to detect radiation. Radium salts were used in the past to paint the dials of luminous clock faces that glow in the dark. 

The combination of the picosecond single electron bunch with streak cameras, independently developed in 1979 at Argonne National Laboratory [55] and at University of Tokyo by us [56], enabled the very high time resolution for emission spectroscopy. The research fields have been extended to organic materials such as liquid scintillators [55-57], polymer systems [58], and pure organic solvents [59]. The kinetics of the geminate ion recombination were studied [55,57,59]. 

Hirayama, F. Lipsky, S. Saturated Hydrocarbons as Donors in Electronic Energy Transfer Processes New York. In Organic Scintillators and Liquid Scintillation Counting Horrocks, D.L., Peng, C.-T., Eds. Academic Press, 1971 205 pp. 

To extract the liberated fatty acids, 1.5 ml of 0.1 mM carbonate-bicarbonate buffer, pH 10.5 is added and the mixture is shaken for 10 s. Centrifugation for 45 min at 1500 xgin a swing-out rotor will separate the water from the lower organic phase. In a scintillation vial, 2 ml of the upper water phase are mixed with 50 pi of glacial acetic acid containing 500 pg ferric acid before the scintillation liquid is added (16 ml of Ecoscint toluene (7 1 volume). Liquid scintillation counting is done for 5 min and the LPL activity is calculated from the difference in counts between the blank and the sample vials [40]. 

In a conventional logging apparatus, the scintillation material is comprised of a specially formulated organic polymer or plastic. Many conventional plastic scintillators do not exhibit acceptable mechanical and optical properties when used at relatively high temperature of 75-175°C encountered in a borehole. 

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