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Semiconductor Detectors
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
The TlBr is a compound semiconductor material that currently mainly exists at an experimental stage: commercial TlBr crystals are available but are not yet as ready-to-use detector systems. TlBr used as a spectrometric detector for γ-radiation was first reported in the mid-eighties, although research on mixed thallium bromide/iodide as detector for ionizing radiation was initiated much earlier [43]. TlBr is a competitive future low-cost alternative to CZT for room-temperature use. CZT currently being the only room-temperature operated high-resolution semiconductor detector for γ-spectrometry. Properties of TlBr and the competitive scintillator materials BGO and LYSO are listed in Table 7.3
Plastics Properties and Testing
Published in Manas Chanda, Plastics Technology Handbook, 2017
Pelletization with potassium bromide powder is advantageous for insoluble samples. (The concentration of the sample in KBr should be in the range of 0.2% to 1%.) Instead of potassium bromide, other suitable materials such as thallium bromide, silver chloride, or polyethylene can be used as the basis of sample pellets. Mulls in nujol placed between AgCl, NaCl, KBr, or CsI plates or KBr pellets are also suitable for insoluble samples. (Nujol is a heavy paraffin oil with essentially alkane formula CnH2n+2, where n is very large.) The halides are ionic and usually do not have any absorption peaks in the range normally covered in the IR spectrum. However, the presence of absorption bands attributed to CH2 in nujols makes the analysis of vibrations of methylene groups impossible. Polymer samples can also be prepared as very thin platelets by cutting with a microtome, or in the form of fibers if special microscopic equipment is available.
Survey of Sensor Mechanisms
Published in Robert B. Northrop, Introduction to Instrumentation and Measurements, 2018
Crystal radiation sensors have used crystals of materials such as lightly chlorine-doped cadmium telluride (a p semiconductor), thallium chloride–thallium bromide, silver chloride, silver bromide, and diamond on which metallic electrodes have been deposited on opposite surfaces. A DC potential is applied to the electrodes, generating an internal electric field in the crystal of several kV/cm. If an ionizing particle enters the crystal and collides with its atoms, a burst of free electrons is released that then drift through the crystal to the positive electrode where their arrival causes a brief current pulse. Only 1.0 eV is required in a Cl-doped CdTe crystal to put an electron into the conduction band.
Varying the secondary coordination sphere: synthesis of cobalt and iron complexes of a tripodal ligand featuring two hydrogen-bond donors or acceptors
Published in Journal of Coordination Chemistry, 2020
Courtney L. Ford, Tabitha J. Miller, Yun Ji Park, Niknaz Iranmanesh, Danielle L. Gray, Alison R. Fout
To avoid contact with oxygen and water, all air- and moisture-sensitive manipulations were carried out under an atmosphere of dinitrogen in an MBraun inert atmosphere drybox or using standard Schlenk techniques. Solvents for air- and moisture-sensitive manipulations were dried and deoxygenated using a Glass Contour System and stored over 4 Å molecular sieves prior to use. Celite 545 was heated to 150 °C under dynamic vacuum for 24 h prior to use in the drybox. All reagents were purchased from commercial sources and used as received unless otherwise noted. Ferrous trifluoromethanesulfonate [22] and cobaltous trifluoromethanesulfonate [23] were synthesized according to literature procedure. NMR solvents (acetonitrile-d3, tetrahydrofuran-d8 and chloroform-d1) were degassed and stored over 4 Å molecular sieves prior to use. NMR spectra were recorded at ambient temperature on a Varian spectrometer operating at 500 MHz (1H-NMR), 126 MHz (13C-NMR), and 470 MHz (19F-NMR) and referenced to the peak of the residual solvent (δ parts per million and J in Hz). Solid-state infrared spectra were measured using a Perkin Elmer Frontier FTIR spectrophotometer equipped with a KRS5 thallium bromide/iodide universal attenuated total reflectance accessory. Electrospray ionization mass spectrometry (ESI) was performed using a Waters Q-TOF Ultima ESI instrument. Elemental analyses were performed by the University of Illinois at Urbana-Champaign School of Chemical Sciences Microanalysis Laboratory in Urbana, IL. Solid-state structural characterization was completed using a Bruker D8 Venture Duo or Bruker X8ApexII diffractometer at the George L. Clark X-Ray Facility and 3M Material Laboratory at the University of Illinois at Urbana-Champaign.