Lanthanum(III) bromide

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Lanthanum(III) bromide
UCl3 without caption.png
Lanthanum bromide (space filling) 1.png
Names
IUPAC names
Lanthanum(III) bromide
Lanthanum tribromide
Identifiers
13536-79-3 YesY
ChemSpider 75393 YesY
EC number 36-896-7
Jmol-3D images Image
PubChem 83563
Properties
LaBr3
Molar mass 378.62 g/mol (anhydrous)
Appearance white solid, hygroscopic
Density 5.06 g/cm3, solid
Melting point 783 °C (1,441 °F; 1,056 K)
Boiling point 1,577 °C (2,871 °F; 1,850 K)
Not Published Yet (very soluble in water)
Structure
Crystal structure hexagonal (UCl3 type), hP8
Space group P63/m, No. 176
Tricapped trigonal prismatic
(nine-coordinate)
Hazards
EU classification not listed
Flash point not flammable
Related compounds
Other anions
Lanthanum(III) fluoride
Lanthanum(III) chloride
Lanthanum(III) iodide
Other cations
Cerium(III) bromide
Praseodymium(III) bromide
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Lanthanum(III) bromide (LaBr3) is an inorganic halide salt of lanthanum. When pure, it is a colorless white powder. The single crystals of LaBr3 are hexagonal crystals with melting point of 783 °C. It is highly hygroscopic and water soluble. There are several hydrates, La3Br·X H2O, of the salt also known. It is often used as a source of lanthanum in chemical synthesis, and is being evaluated for use as a scintillation material in certain applications.

Uses[edit]

Cerium activated lanthanum bromide is the recent inorganic scintillator which has a combination of high light yield and the best energy resolution.

Lanthanum bromide scintillation detector[edit]

Recent advances in scintillator material have resulted in the development of cerium activated lanthanum bromide (LaBr3) detectors. LaBr3 was discovered in 2001.[1] These detectors offer improved energy resolution, fast emission and excellent temperature and linearity characteristics. Typical energy resolution at 662 keV is 3% as compared to sodium iodide detectors at 7%.[2] The improved resolution is due to a photoelectron yield of 160% that achieved with sodium iodide. Another advantage of LaBr3 is the nearly flat photo emission over a 70 °C temperature range (~1% change in light output)[citation needed].

Today LaBr3 detectors are offered with bialkali photomultiplier tubes (PMT) that can be two inches in diameter and 10 or more inches long[citation needed] . However, miniature packaging can be obtained by the use of a silicon drift detector (SDD). These UV enhanced diodes provide excellent wavelength matching to the 380 nm emission of LaBr3. A paper presented at the 2005 IEEE Nuclear Science Symposium shows that the SDD has a higher quantum efficiency over the PMT[citation needed]. Moreover the SDD is not as sensitive to temperature and bias drift. The reported spectroscopy performance of the SDD configuration resulted in a 2.8% energy resolution at 662 keV for the detector sizes considered.

LaBr3 introduces an enhanced set of capabilities to a range of gamma spectroscopy radioisotope detection and identification systems used in the homeland security market. Isotope identification utilizes several techniques (known as algorithms) which rely on the detector’s ability to discriminate peaks. The improvements in resolution allow more accurate peak discrimination in ranges where isotopes often have many overlapping peaks. This leads to better isotope classification. Screening of all types (pedestrians, cargo, conveyor belts, shipping containers, vehicles, etc.) often requires accurate isotopic identification to differentiate concerning materials from non-concerning materials (medical isotopes in patients, naturally occurring radioactive materials, etc.) Heavy R&D and deployment of instruments utilizing LaBr3 is expected in the upcoming years. (List of companies who manufacture commercial off-the-shelf Radiation Isotope Identifiers for Homeland Security: Canberra Industries, ORTEC, Berkeley Nucleonics, spectra sample and spectroscopy example])

References[edit]

  1. ^ E. V. D. van Loef, P. Dorenbos, C. W. E. van Eijk, K. W. Kraemer and H. U. Guedel Appl. Phys. Lett. 79 2001 1573
  2. ^ Knoll, Glenn F., Radiation Detection and Measurement 3rd ed. (Wiley, New York, 2000).