Optical and vibronic spectra of MnO in cesium bromide

Radhakrishna, S.; Hariharan, K.

doi:10.1002/pssb.2220920134

Cited by 9 publications

(3 citation statements)

References 12 publications

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“…Our conclusion about the nature of the chromophores and luminophores in MnO 4 2- -doped halides is at variance with earlier studies in which it was assumed that MnO 4 2- ions were substituting for halide ions in the host lattice . No luminescence spectra were available in these earlier investigations, whereas the most conclusive evidence for the presence of Cs 2 MnO 4 cystallites in our work is the spectral and temporal behavior of the luminescence.…”

Section: Discussioncontrasting

confidence: 59%

“…But the first luminescence spectra of MnO 4 2- doped into a variety of host lattices such as K 2 MO 4 (M = S, Cr, Se), Cs 2 SO 4 , and BaMO 4 (M = S, Cr, Se) were reported only very recently. , From a thorough analysis of the absorption and luminescence spectra of MnO 4 2- in the Cs 2 SO 4 and BaSO 4 hosts, a detailed picture of the electronic structure and vibronic interactions in the 2 E and 2 T 2 LF states could be derived. Optical absorption, ESR, and Raman spectra of MnO 4 2- doped into CsBr and CsI and other alkali-metal halides were reported; but a detailed analysis of their optical spectra is still lacking, likely due to the poorly resolved absorption spectra and the lack of luminescence spectra.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and Optical Spectroscopy of MnO₄²^--Doped Crystals of Cs₂CrO₄, SrCrO₄, CsBr, and CsI

1998

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The first low-temperature absorption and luminescence spectra of MnO4 2--doped crystals of Cs2CrO4, SrCrO4, CsBr, and CsI are reported. Single crystals of Cs2CrO4:MnO4 2-, which crystallize in the orthorhombic β-K2SO4 structure, were grown from basic aqueous solutions. An alkali−chloride flux composition was used to obtain single crystals of SrCrO4:MnO4 2- with the monoclinic monazite structure. Crystals of CsBr:MnO4 2- and CsI:MnO4 2- were prepared by slowly cooling the melt. The site symmetry in SrCrO4 is C 1, but the deviations from D 2 symmetry are small, and the spectra are analyzed in the approximate D 2 symmetry. The 2E ↔ 2T2 ligand-field transitions are strongly c polarized, and in absorption only the transition to the lowest-energy component of the split 2T2 state is observed with its origin at 10 303 cm-1. Luminescence is exclusively observed to the lower-energy component of the 2E state. By a combination of absorption and luminescence data, it is shown that, in the cubic CsBr and CsI lattices, MnO4 2- is partly incorporated in the form of Cs2MnO4 crystallites. The observed nonexponential luminescence decay for these systems indicates the existence of several manganese(VI) species with different relaxation times. Within isomorphous host lattices, a correlation is established between the temperature-quenching behavior and the size of the M6+ host ion: the efficiency of multiphonon relaxation processes increases with increasing ionic radius of M6+.

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Section: Discussioncontrasting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Synthesis and Optical Spectroscopy of MnO₄²^--Doped Crystals of Cs₂CrO₄, SrCrO₄, CsBr, and CsI

1998

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“…12 Mn 6+ can easily substitute for S 6+ , Cr 6+ , Se 6+ , and Mo 6+ in host lattices such as SO 4 2− , CrO 4 2− , SeO 4 2− , and MoO 4 2− , respectively. [13][14][15][16][17][18][19][20][21][22] (Mn 6+ , Mn 5+ )-doped BaSO 4 crystal is considered as one of the most promising candidates for tunable NIR solid-state laser materials among the Mn ion doped systems investigated due to broad emission range in the NIR wavelength region, low solubility in water and higher quantum efficiency. 23,24 Mn 2+ and Mn 4+ ions are known as efficient activator ions in various hosts, and these Mn ions usually emit light only in the visible region.…”

mentioning

confidence: 99%

Spectroscopic Investigation on BaSO₄:(Mn⁶⁺, Mn⁵⁺) Crystal

Cao

Qiu

et al. 2013

ECS J. Solid State Sci. Technol.

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BaSO4:(Mn6+, Mn5+) crystal was grown using MnCO3 as manganese source at high temperature from 650 to 750°C by the NaCl-KCl flux method in air and its spectroscopic properties were investigated. The experimental results indicate that Mn6+ and Mn5+ ions coexisted in the crystal. A broadband emission band peaking at ∼1060 nm due to the 2T2 → 2E transition of Mn6+ ion and a sharp emission band peaking at ∼1183 nm due to the 1E → 3A2 transition of Mn5+ ion were observed. Mn-doped BaSO4 single crystal may be a promising candidate as tunable near-infrared solid-state laser material.

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Sulphur molecular ion centers in cesium bromide

Radhakrishna

Hariharan

1981

Cryst Res and Technol

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IatroducticnlThe study of the properties of molecular impurities in different crystalline matrices has acquired specialinterest becausetheabovestudy givesinformation abouttheorientationofthe vation of forbidden modes in Raman or IR rncBsWements and splitting of degenerate modes due to lowering of symmetry. It is known (VANOTIT, MORTEN; HOLZER et al.) that the homonuclear diatomic molecule $ -occupies a single halogen vacancy in alkalihalide lattices and has only one vibrational frequency which is Raman active and IR inactive. The above impumolecule, changes in vibrational tkquencies from those characterizing a free ion, actirity is paramagnetic and has c h t e r i s t i c absorption and emission bands @om; IKBZAWA, Rom). In the process of doping a crystal with S ; , one cannot avoid the presence of &-ions also. &-is a bent triatomic molecule and has three vibrational frequencies. It occupies a trivacancy (SWALSKI, S~E L ) (one cation, two anions) in the crystal lattice. Several studies on alkali halides doped with sulphur molecular centres have shown simultaneous existence of both these impurities. While a good deal of work (VANOTTI, MORTW; SWALSKI, SEIDEL) has been done on negative molecular centers such as O; , S ; and !k$-embedded in fcc crystalline matrices such as NaI, KI etc., little work has been reported on the behaviour of such centres in cesium halides. H e n c e in the present study, optical and infrared absorption studies on cesium bromide doped with 5&-and S ; ions have been carried out. ExperimentalSingle crystals doped with S ; and S; molecular ions were obtained by heating the crystal in the presence of sulphur vapour. Cesium bromide crystals Were grown by Bridgmao technique. Small crystals (typically 5 x 2 x 10 mm3) were placed in quartz tubes, with small amount of sulphur which were sealed off after evacuation. The above system was heated in a furnace for I20 hours at a temperature of 600 "C.Curve 1 of Figure 1 shows the optical absorption spectrum of CsBr doped with sulphur at room temperature. There are two well defined bands around 6050 A and 4OOO A. The IR absorption spectrum of the crystal shows a line ai 580 cm-'. When the crystal is subjected to W irradiation, the band at 6050 A vanishes and the IR line at 580 cm-' also vanishes. This shows that the band at 4ooo A is due to one origin and the band at 6050 A with IR line at 580 an-' is due to another origin. It is kwwn (HOLZER et al.) that S ; ion has a simple Raman active vibrational frequency at 594 cm-', while S ; ion has noncoincident Raman and IR active modes at 546 cm-' and 585 cm-'. Since %-ion species is symmetrical and diatomic, no infrared absorption band is observed. Hence, one can conclude from the above discussion that the species which disappears on UV irradiation is attributed to &-with a broad band at 6050 A and IR line at 580 cm-' and the absorption band at 4OOO A to

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Optical and vibronic spectra of MnO in cesium bromide

Cited by 9 publications

References 12 publications

Synthesis and Optical Spectroscopy of MnO₄²^--Doped Crystals of Cs₂CrO₄, SrCrO₄, CsBr, and CsI

Synthesis and Optical Spectroscopy of MnO₄²^--Doped Crystals of Cs₂CrO₄, SrCrO₄, CsBr, and CsI

Spectroscopic Investigation on BaSO₄:(Mn⁶⁺, Mn⁵⁺) Crystal

Sulphur molecular ion centers in cesium bromide

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Optical and vibronic spectra of MnO in cesium bromide

Cited by 9 publications

References 12 publications

Synthesis and Optical Spectroscopy of MnO42--Doped Crystals of Cs2CrO4, SrCrO4, CsBr, and CsI

Synthesis and Optical Spectroscopy of MnO42--Doped Crystals of Cs2CrO4, SrCrO4, CsBr, and CsI

Spectroscopic Investigation on BaSO4:(Mn6+, Mn5+) Crystal

Sulphur molecular ion centers in cesium bromide

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Synthesis and Optical Spectroscopy of MnO₄²^--Doped Crystals of Cs₂CrO₄, SrCrO₄, CsBr, and CsI

Synthesis and Optical Spectroscopy of MnO₄²^--Doped Crystals of Cs₂CrO₄, SrCrO₄, CsBr, and CsI

Spectroscopic Investigation on BaSO₄:(Mn⁶⁺, Mn⁵⁺) Crystal