EPR study of gamma-irradiated Na2S2O3·5H2O single crystals

Yıldırım, İlkay; Karabulut, Bünyamin; Bozkurt, Esat; Köksal, Fevzī

doi:10.1016/j.radphyschem.2008.11.007

Cited by 5 publications

(2 citation statements)

References 8 publications

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“…Further analysis of the EPR spectra reveals the presence of two distinct sulfur based radicals, specifically assigned to S 2 O − and S 2 O 2 − centers (see Figure S8 in the Supporting Information for details of the simulations). [ 25 ] The spin Hamiltonian parameters (Table 1) for these two sulfur radicals are slightly different compared to those reported previously in CaS powders, [ 15 ] and this may be an artefact of the different synthesis methods employed. No sharp isotropic signal due to any

V_{S}^{•}

centers were observed, which could indicate that such species are stabilized by cationic Eu 3+ defects,

{Eu}_{Ca}^{•}

, as suggested in previous EPR studies.…”

Section: Resultsmentioning

confidence: 66%

CW EPR Investigation of Red‐Emitting CaS:Eu Phosphors: Rationalization of Local Electronic Structure

Spencer

Merrikin

Pope

et al. 2020

Advanced Optical Materials

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It is the unique electronic structure of the f-block elements that is responsible for their desirable catalytic, magnetic and photophysical properties. These phosphors can be broadly classified into two groups, based on the desired electronic transition and emission band width required; namely, broad band 5d → 4f interelectronic transitions possessing a short radiative lifetime (cf. 1 µs) and sharp emission bands arising from 4f → 4f intraelectronic transitions, that are La-Porte forbidden, possessing a longer radiative lifetime (cf. 1 ms). [10] The 4f subshell is relatively insensitive to the local environment, due to the screening of occupied 5s and 5p subshells which reduce the electrostatic potential of the ligand field. Therefore, the sharp f-f band transitions are usually weakly affected by an external bias, although the relative intensities can be perturbed significantly. The relative energy and degeneracy of the 5d orbitals are in contrast significantly influenced by the crystal field. Consequently, the relative energy between the 4f and 5d states, and thus the corresponding emissive wavelength, is readily tuned by the coordination environment. After the Coulombic and crystal field effects, other important considerations include dopant concentration, particle size distribution, crystallinity and concentration of defects or impurities within the material which may compete with the lanthanide activator. As a result, the specific luminescent intensity of the broad band may be reduced via interaction with these impurities, either by competition for incident optical absorption, energy transfer processes, or quenching of luminescent emission at the desired wavelength. [11,12] The luminescent efficiency of phosphors is also highly dependent on the relaxation properties of the activator during absorption and emission, i.e., the amount of energy lost to the lattice as heat, [9] which must be minimized to preserve the overall quantum yield. Eu 2+-doped calcium sulfide (labeled hereafter as CaS:Eu) phosphors have in particular recently generated considerable interest as solid state light sources for algae growth, owing to the broad band red emission near λ = 645 nm. Eu is readily found in the divalent oxidation state due to a half-filled 4f subshell and resulting stabilization energy. Over 300 Eu 2+ compounds in different host matrices have been reported to date, where the emission color of the 5d-4f transition has been tuned A series of commercial and prepared CaS:Eu 2+ rare earth activated phosphors are investigated following different post-synthetic treatments. A number of species directly related to the function of the material are characterized using electron paramagnetic resonance (EPR) spectroscopy. Isolated Eu 2+ sites are identified and associated with the substitutional doping for Ca 2+ in the lattice which are responsible for the 645 nm emission of interest. Another inactive Eu 2+ site based within a "EuO" type phase aggregated on the surface of the material is also identified, as well as competitive F + ...

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V_{S}^{•}

centers were observed, which could indicate that such species are stabilized by cationic Eu 3+ defects,

{Eu}_{Ca}^{•}

, as suggested in previous EPR studies.…”

Section: Resultsmentioning

confidence: 66%

CW EPR Investigation of Red‐Emitting CaS:Eu Phosphors: Rationalization of Local Electronic Structure

Spencer

Merrikin

Pope

et al. 2020

Advanced Optical Materials

View full text Add to dashboard Cite

show abstract

“…Fourier Transform Infrared (FT-IR) spectral studies of nickel amine complexes showed significant changes in position and intensity of characteristic bands after irradiation [8,9]. Literature survey revealed that impact of irradiation on single crystals and subsequent changes in photoluminescence (PL) properties have been investigated [10,11]. PL studies of pure and gamma irradiated L-alanine, single crystal showed that the PL intensity was enhanced upon irradiation.…”

Section: Introductionmentioning

confidence: 99%

X-ray diffraction, spectroscopic, thermal and surface morphological studies of gamma-irradiated diaquamalonatomanganese(II) (DMM)

Sumithra

Jayashri

Krishnan

2015

J Radioanal Nucl Chem

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The effect of gamma irradiation on single crystal and powdered samples of diaquamalonatomanganese(II) was investigated. Thermal, spectral and surface morphological studies were also performed using the powdered samples before and after irradiation. Single crystal as well as PXRD studies showed that both unirradiated and irradiated samples are orthorhombic. Changes in lattice parameters upon irradiation are different in powder and single crystal of the same material. Thermal decomposition profiles of unirradiated and irradiated samples are found to be similar. Upon irradiation significant changes were observed in spectral features. AFM studies revealed morphological changes and enhanced roughness in the irradiated sample.

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Electron paramagnetic resonance of gamma-irradiated single crystals of ethan-1,2 disulfonic acid disodium

Karataş¹,

Aras²

2012

Journal of Molecular Structure

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EPR study of gamma-irradiated Na2S2O3·5H2O single crystals

Cited by 5 publications

References 8 publications

CW EPR Investigation of Red‐Emitting CaS:Eu Phosphors: Rationalization of Local Electronic Structure

CW EPR Investigation of Red‐Emitting CaS:Eu Phosphors: Rationalization of Local Electronic Structure

X-ray diffraction, spectroscopic, thermal and surface morphological studies of gamma-irradiated diaquamalonatomanganese(II) (DMM)

Electron paramagnetic resonance of gamma-irradiated single crystals of ethan-1,2 disulfonic acid disodium

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