Luminescence Database I—Minerals and MaterialsColin M. MacRae* and Nicholas C. WilsonCSIRO Minerals, Microbeam Laboratory, Bayview Avenue, Clayton, Victoria 3168, AustraliaAbstract: A luminescence database for minerals and materials has been complied from the literature, the aimbeing to create a resource that will aid in the analysis of luminescence spectr al of ionic species in minerals andmaterials. The database is based on a range of excitation techniques and records both major and minor lines,and their activators. The luminescence techniques included in the database are cathodoluminescence, ionluminescence, and photoluminescence. When combined with other traditional X-ray measurements collectedon the same region, use of the luminescence database will give additional insight into the chemistry of mineralsand materials.Key words: luminescence, cathodoluminescence, photoluminescence, ion, mineralsINTRODUCTIONMinerals and materials can luminescence when they areexposed to an electron, X-ray, ion, or photon beam. Lumi-nescence is generally associated with light in the ultraviolet~UV! to infrared ~IR! region and can exhibit both broadand narrow band spectra. From the spectra it is possible toidentify both the activators responsible for the lumines-cence and their charge states. A large number of researchgroups routinely employ luminescence analysis as a keymacro- and micro-characterization techniques in the studyof minerals and materials.For many years the microanalyst has had availableKLM lines for identifying peaks in X-ray spectra; however,no such tool has been available for luminescence generatedby electrons, light, protons, or ions. To address this problema luminescence database of lines has been compiled thatcontains over 1,000 lines or bands from over 70 mineralsand synthetic materials. In this article the luminescencedatabase is described, and in a subsequent article softwaretools and web access will be described. It is the authors’intention to make the database easily accessible and providea procedure for external users to add new lines and spectrafrom minerals and mater ials.A number of minerals have distinguishing lumines-cence properties. These include: diamond, sulphides ~chalco-cite, sphaleri te!, oxides ~periclase, corundum, cassiterite!,halides ~fluorite, halite!, sulphates ~anhydrite, alunite!, wol-framates ~scheelite!, phosphates ~apatite!, carbonates ~cal-cite, dolomite, magnesite, witherite!, or silicates ~ albite,feldspar, quartz, zeolites, kaolinite, forsterite, zircon, garnet,titanite, thorite, willemite!. The presence of luminescence,in many cases, allows rapid identification of the differentmineral constituents using cathodoluminescence micros-copy. This is particularly important if samples consist offine-grained material and/or of minerals with similar opti-cal or crystallographic properties. These grains can then b efurther characterized by electron microprobe or opticalmicroscopy.Furthermore, many of the phases occurring in ceramics~Hagni & Karakus, 1989!, glasses, refractory materials ~Kara-kus, 2005!, and biomaterials show distinct luminescenceproperties allowing a rapid identification of phase distribu-tion and transformations. Luminescence spectroscopy isparticularly important in the characterization of materialsthat contain significant proportions of noncrystalline com-ponents, multiple phases, or low concentrations of mineralphases.LUMINESCENCE FUNDAMENTALSCharacteristic X-ray lines result from core level transitions,while the generation mechanism for luminescence is morecomplex. Characteristic X-rays are largely unaffected bybonding as the core orbitals do not take part and therefore aparticular elemental transition is independent of the hostlattice. However, the luminescence emission is sensitive tomaterial composition and structure of the host lattice, be-cause it originates from effects such as conduction to va-lence transitions and phonon modes ~Marfunin, 1979!. Thismakes luminescence sensitive to subtle effects such as traceReceived November 27, 2007; Accepted January 2, 2008*Corresponding author. E-mail: [email protected]. Microanal. 14, 184–204, 2008doi: 10.1017/S143192760808029XMicroscopyANDMicroanalysis© MICROSCOPY SOCIETY OF AMERIC A 2008level dopants and their valence, the host lattice, and quench-ing ions. This sensitivity results in luminescence providingextremely useful characterization information, but its inter-pretation is more difficult than that of characteristic X-rays.Dopant IonsMinerals and materials often contain optically active dop-ants ions. Generally there are considered to be three types ofdopant ions that influence and determine the net emissionof a particular mineral. They are referred to as activators,sensitizers, or quenchers. Activators produce emission byreleasing the absorbed energy as photons. The most com-mon activators are transition metal ions such as Cr3⫹,Mn2⫹,Mn4⫹,Sn2⫹,Pb2⫹,Fe3⫹~Gotze, 2002!, and rare earthelements ~Marfunin, 1979!. Sensitizers are ions that work incombination with an activator by absorbing the energy andsubsequently transferring the energy to the activator. Quench-ers trap part or all of the absorbed energy resulting innonradiative decay of the energy. As a result, quencherstend to eliminate the emission of light from minerals. Thepresence of the quencher causes new closely spaced energylevels to be set up, and the electron can easily return to theground state with the emission of a succession of low-energy photons ~IR! or by losing energy to the lattice as heat~Marshall, 1988!. An example of a well-recognized quencherion in minerals is Fe2⫹.Types of EmissionLuminescence emission is generally grouped into two types:intrinsic and extrinsic. Intrinsic luminescence is native tohost materials and involves band-to-band recombination ofelectron and hole pairs. Intrinsic luminescence emissionmay also be associated with lattice defects ~anion vacancies!within the minerals or material. This type of luminescenceis also referred to as “defect center” luminescence. Thesecond type of emission, referred to as extrinsic, is the mostcommon form of luminescence. Extrinsic emission is attrib-uted to the presence of trace element impurities, transitionmetal, and rare earth ions. This type of luminescence isreferred to as an “impurity center.”The emission process involves an electronic transitionfrom an excited state ~Ee! to a lower energy level or groundstate ~Eg!.
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