Selective production of aggregate centers in LiF crystals by ionizing radiations

Baldacchini, G.; Nicola, E. De; Giubileo, G.; Menchini, Francesca; Messina, G.; Montereali, R. M.; Scacco, A.

doi:10.1016/s0168-583x(98)00054-8

Cited by 19 publications

(10 citation statements)

References 11 publications

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“…Lithium fluoride, LiF, due to its simple structure, chemical stability, cleaving properties and easy production, is presently among the best known material having lots of applications in the fields of tunable colour centre lasers, radiation dosimeters, optical isolators and a wide range of opto-electronic devices. Defect creation in LiF crystal under various types of irradiation like photons [2], electrons [3][4][5][6][7], neutrons [3] and ions [8][9][10][11][12][13][14][15] has been reported. Many types of primary defects have been observed in LiF crystals.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, the irradiation leads to the creation of single defects and defect aggregates consequently. A large number of studies have been done on colour centres in LiF crystals [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. However, little work exists on colour centres in LiF films [2,6,11,12], whereas only a few reports are available on SHI induced colour centres in LiF films [11,12].…”

Section: Introductionmentioning

confidence: 99%

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Studies of swift heavy ion induced colour centres in LIF thin films deposited on silica substrates

Kumar¹,

Singh²,

Khan³

et al. 2006

J. Phys. D: Appl. Phys.

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Swift heavy ion induced colour centres in polycrystalline LiF thin films deposited on silica substrate were studied. LiF thin films of 200 nm thickness, deposited by the electron beam evaporation method, and silica substrates were irradiated with 120 MeV Au9+ ions in the fluence range 5 × 1010–1 × 1013 ions cm−2. Optical absorption, photoluminescence (PL) and glancing angle x-ray diffraction (GAXRD) techniques were used for the characterization of the irradiated films. Optical absorption spectroscopy was performed on irradiated LiF films by using irradiated silica substrates as reference sample. The resulting spectra show three bands at 260 nm, 380 nm and 445 nm corresponding to F, F3 and F2 colour centres, respectively. Absorbance of colour centres increases with fluence and seems to saturate at higher fluences. PL spectra, performed by an excitation source of 442 nm, show two broad bands of F2 and colour centres. The intensity of both the centres increases upto 3 × 1011 ions cm−2 followed by some decrease. The GAXRD results show that the average grain size decreases systematically from 35 nm for the pristine film to 20 nm for the sample irradiated at a fluence of 1 × 1013 ions cm−2.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Studies of swift heavy ion induced colour centres in LIF thin films deposited on silica substrates

Kumar¹,

Singh²,

Khan³

et al. 2006

J. Phys. D: Appl. Phys.

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“…1 [4,5]. The LNT irradiated films also showed the same bands with a new band at 520 nm, corresponding to F 4 centers [4]. Absorption of CCs increases with fluence indicating an increase in their concentration.…”

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confidence: 71%

Swift heavy ion induced effects in LiF thin films

Kumar

Singh

Khan

et al. 2007

Phys. Status Solidi (c)

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Swift heavy ions induced effects on optical (color centers), structural and surface (electronic sputtering and morphology) modifications, in nano-grains LiF thin films were studied by glancing angle X-ray diffraction, optical absorption, photoluminescence and elastic recoil detection analysis techniques. Our results show that grain size and irradiation temperature play a crucial role in materials modifications as a function of fluence for the selected ion beam parameters. Also for the first time, lamellae formation was observed in LiF thin films after a high fluence irradiation of 5×10 13 ions/cm 2 at liquid nitrogen temperature with 120 MeV Ag ions irradiation under grazing incidence (~10°).1 Introduction The bombardment of solid surfaces by ionizing radiation has great deal of attraction due to many interesting fundamental and technical aspects of ion beam induced effects. Ionizing irradiation is known for synthesis, modifications and characterization of materials. The ions having kinetic energy in the range of few MeV/u, known as swift heavy ions (SHI), interact with the target materials mainly via electronic excitation resulting in interesting effects on physical and chemical properties of the materials. Lithium Fluoride (LiF) has lots of applications in the fields of tunable color center lasers, radiation dosimeters, optical isolators and in other wide range of opto-electronic devices. Ion induced effects in LiF has been studied, mostly in the form of bulk [1][2][3][4][5][6]. Aim of the present work is to study the effect of SHI irradiation on nanometer sized LiF thin films. In case of thin films, the structural and optical properties are strongly influenced by growth and irradiation parameters. Therefore, it would be interesting to study the SHI induced effects like color centers (CCs), electronic sputtering (i.e. the removal of target materials) and surface restructuring in nanometer sized thin films of LiF.

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“…18 Figure 10 shows the absorption spectra of two LiF crystals colored with the same irradiation dose, but at different temperatures. 18 Figure 10 shows the absorption spectra of two LiF crystals colored with the same irradiation dose, but at different temperatures.…”

Section: Resultsmentioning

confidence: 99%

Concentration Quenching of Photoluminescence

Baldacchini

Menchini

Montereali

2003

J. Electrochem. Soc.

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The relative emission efficiency of F 3 ϩ and F 2 centers as a function of their concentration has been investigated in LiF crystals colored at room temperature and Ϫ60°C with 3 MeV electrons. From a careful study of their absorption and emission spectra, we discovered that the emission efficiency of both F 3 ϩ and F 2 defects is constant up to ϳ10 16 centers/cm 3 . When increasing the concentration up to 10 18 centers/cm 3 , decreases slightly for the F 2 centers and considerably for the F 3 ϩ ones, a difference which is bigger at room temperature with respect to liquid nitrogen temperature. A thermally activated process is taking place, where the F 2 center and other aggregated defects play an important role.

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Selective production of aggregate centers in LiF crystals by ionizing radiations

Cited by 19 publications

References 11 publications

Studies of swift heavy ion induced colour centres in LIF thin films deposited on silica substrates

Studies of swift heavy ion induced colour centres in LIF thin films deposited on silica substrates

Swift heavy ion induced effects in LiF thin films

Concentration Quenching of Photoluminescence

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