Local symmetry breaking in SnO2 nanocrystals with cobalt doping and its effect on optical properties

Nanoscale ◽  
2018 ◽  
Vol 10 (22) ◽  
pp. 10664-10682 ◽  
Author(s):  
S. Roy ◽  
Amish G. Joshi ◽  
S. Chatterjee ◽  
Anup K. Ghosh

Local symmetry breaking in Sn1−xCoxO2 (0.00 ≤ x ≤ 0.04) nanocrystals as evident from Raman spectra (a), and its effect on UV- and green- emissions (b).

Nanoscale ◽  
2020 ◽  
Author(s):  
Feifei ZHANG ◽  
Jérôme Plain ◽  
Davy Gerard ◽  
Jérôme Martin

The surface topography is known to play an important role on the near- and far- field optical properties of metallic nanoparticles. In particular, aluminum (Al) nanoparticles are commonly fabricated through...


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aadil Ahmad Bhat ◽  
Shakeel Ahmad Khandy ◽  
Ishtihadah Islam ◽  
Radha Tomar

AbstractThe present manuscript aims at the synthesis of cesium based halide perovskite nanostructures and the effect of cobalt doping on the structural, optical, lumnisent, charge storage and photocatalytic properties. In a very first attempt, we report the solvothermal synthesis of Co doped CsPbCl3 nanostructures under subcritical conditions. The structural features were demonstrated by X-ray diffraction (XRD) Surface morphology determined cubic shape of the synthesized particles. Doping is an excellent way to modify the properties of host material in particular to the electronic structure or optical properties. Incorporation of Co2+ ions in the perovskite structure tunes the optical properties of the nanostructures making this perovskite a visible light active material (Eg = 1.6 eV). This modification in the optical behaviour is the result of size effect, the crystallite size of the doped nanostructures increases with cobalt doping concentration. Photolumniscance (PL) study indicated that CsPbCl3 exhibited Blue emission. Thermogravametric analysis (TGA) revealed that the nanostructures are quite stable at elavated temperatures. The electrochemical performance depicts the pseudocapacative nature of the synthesized nanostructures and can used for charge storage devices. The charge storage capability showed direct proportionality with cobalt ion concentration. And Finally the photocatalytic performance of synthesized material shows superior catalytic ability degrading 90% of methylene blue (MB) dye in 180 min under visible light conditions.


1983 ◽  
Vol 213 (2) ◽  
pp. 503-506 ◽  
Author(s):  
G Musci ◽  
A Desideri ◽  
L Morpurgo ◽  
A Garnier-Suillerot ◽  
L Tosi

Resonance-Raman spectra of Japanese-lacquer-tree (Rhus vernicifera) laccase, type-2-copper-depleted laccase and the latter form treated with H2O2 were measured in liquid and frozen solution, on excitation into the 600 nm absorption band. Significant changes in intensity and/or frequency of the bands lying in the 370-430 cm-1 region were observed on freezing, indicating local structural rearrangements taking place at the blue copper site. These findings corroborate previous suggestions based on e.p.r. measurements and redox data [Morpurgo, Calabrese, Desideri & Rotilio (1981) Biochem. J. 193, 639-642]. They show the strong dependence of the physical properties of blue copper centres on local symmetry. Some conclusions on the origin of the Raman bands are also drawn.


MRS Advances ◽  
2018 ◽  
Vol 3 (14) ◽  
pp. 711-716 ◽  
Author(s):  
Peter C. Sercel ◽  
Andrew Shabaev ◽  
Alexander L. Efros

ABSTRACTWe have analysed the effect of symmetry breaking on the optical properties of semiconductor nanocrystals due to doping by charged impurities. Using doped CdSe nanocrystals as an example, we show the effects of a Coulomb center on the exciton fine-structure and optical selection rules using symmetry theory and then quantify the effect of symmetry breaking on the exciton fine structure, modelling the charged center using a multipole expansion. The model shows that the presence of a Coulomb center breaks the nanocrystal symmetry and affects its optical properties through mixing and shifting of the hole spin and parity sublevels. This symmetry breaking, particularly for positively charged centers, shortens the radiative lifetime of CdSe nanocrystals even at room temperature, in qualitative agreement with the increase in PL efficiency observed in CdSe nanocrystals doped with positive Ag charge centers [A. Sahu et.al., Nano Lett. 12, 2587, (2012)]. The effect of the charged center on the photoluminescence and the absorption spectra is shown, with and without the presence of compensating charges on the nanocrystal surface. While spectra of individual nanocrystals are expected to shift and broaden with the introduction of a charged center, configuration averaging and inhomogeneous broadening are shown to wash out these effects. The presence of compensating charges at the NC surface also serves to stabilize the band edge transition energies relative to NCs with no charge centers.


2019 ◽  
Vol 150 (11) ◽  
pp. 114501 ◽  
Author(s):  
Kazuhiro Fuchizaki ◽  
Takahiro Sakagami ◽  
Hiroshi Iwayama

2012 ◽  
Vol 583 ◽  
pp. 399-402
Author(s):  
Dong Mei Zhao ◽  
Xue Peng Liu

On the basis of measuring its Raman spectra in material engineering with four kinds of geometrical configurations laser scattering method is utilized. Compared with other scheelite scintillators crystals, the blue luminescent center is the regular lattice ,green luminescent center is (WO3+F). Finally the crystal’s luminescent spectra is measured


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