Raman and absorption spectra of the zeolites A and X containing selenium and tellurium in the nanopores

Poborchii, Vladimir; Ivanova, M. S.; Petranovskii, Vitalii; Barnakov, Yu. A.; Kasuya, A.; Nishina, Y.

doi:10.1016/s0921-5093(96)10365-8

Cited by 29 publications

(36 citation statements)

References 8 publications

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“…As a result, a detailed average structural model is presented for the Se/Nd-Y system. Our results are favorably compared with the Raman studies of Poborchii et al 18 and the theoretical studies of Demkov and Sankey 19 on Se/ zeolite-A system ͑the zeolite-A framework contains ϳ11.4 Å diameter cages͒. Pronounced diffuse scattering present in our x-ray-diffraction pattern will also be discussed in terms of intramolecular disorder, another feature of our data ͑and of the HgSe data 3,10 ͒.…”

Section: Introductionsupporting

confidence: 83%

Structure of selenium clusters in the framework of zeolite Nd-Y

Abeykoon

Li²,

Castro-Colín

et al. 2009

Phys. Rev. B

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A detailed model for the structure of selenium clusters in the framework of zeolite Nd-Y has been determined by x-ray powder diffraction. The model, which is consistent with previous theoretical and Raman studies, was determined by analysis of the data. We propose the coexistence of isolated Se 12-membered rings and Se nanoclusters made out of these 12 rings in the ␣ cages of zeolite-Y. Our x-ray data also show substantial diffuse scattering associated with considerable disorder within the pores of the Se/zeolite-Y system. Our work on these systems has made use of a total Rietveld refinement to obtain the average nanomolecular structure.

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Section: Introductionsupporting

confidence: 83%

Structure of selenium clusters in the framework of zeolite Nd-Y

Abeykoon

Li²,

Castro-Colín

et al. 2009

Phys. Rev. B

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“…Nanopores of zeolites have also been used to capture nanoparticles of Se and Te. 118 Raman spectra showed evidence of trapping of either a molecular Se 8 or Te 8 or formation of an irregular array of chains and clusters depending on the size and connectivity of pores.…”

Section: Monoatomic Systemsmentioning

confidence: 99%

Raman spectroscopy of optical phonon confinement in nanostructured materials

Arora

Rajalakshmi

Ravindran

et al. 2007

J Raman Spectroscopy

349

294

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If the medium surrounding a nano-grain does not support the vibrational wavenumbers of a material, the optical and acoustic phonons get confined within the grain of the nanostructured material. This leads to interesting changes in the vibrational spectrum of the nanostructured material as compared to that of the bulk. Absence of periodicity beyond the particle dimension relaxes the zone-centre optical phonon selection rule, causing the Raman spectrum to have contributions also from phonons away from the Brillouin-zone centre. Theoretical models and calculations suggest that the confinement results in asymmetric broadening and shift of the optical phonon Raman line, the magnitude of which depends on the widths of the corresponding phonon dispersion curves. This has been confirmed for zinc oxide nanoparticles. Microscopic lattice dynamical calculations of the phonon amplitude and Raman spectra using the bond-polarizability model suggest a power-law dependence of the peak-shift on the particle size. This article reviews recent results on the Raman spectroscopic investigations of optical phonon confinement in several nanocrystalline semiconductor and ceramic/dielectric materials, including those in selenium, cadmium sulphide, zinc oxide, thorium oxide, and nano-diamond. Resonance Raman scattering from confined optical phonons is also discussed.

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“…0.14 a.u. for the Se 8 and Se 12 clusters incorporated in zeolite A [23,29]. The ha e i(-x;x) values are given in Table 6 together with the static figures for comparison.…”

Section: Dipole Polarizabilitiesmentioning

confidence: 99%

“…The structure of evennumbered Se 6 , Se 8 and Se 12 clusters introduced into monodimensional channels of AlPO 4 -5 single crystals, mordenite and zeolite cavities were extensively characterized by Raman spectroscopy [12,13,[23][24][25][26][27][28][29][30][31][32][33][34]. Selenium clusters adsorbed into zeolite channels are bonded to each other and to the host matrices by van der Waals forces controlled by the polarizabilities of the clusters [21,35].…”

Section: Introductionmentioning

confidence: 99%

Structural, energetic and response electric properties of cyclic selenium clusters: an ab initio and density functional theory study

Alparone

2012

Theor Chem Acc

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The geometries, relative stabilities, binding energies, second-order difference of total energy (D 2 E), vertical ionization energies (VIEs), vertical electron affinities (VEAs) and dipole polarizabilities of neutral Se 2 and cyclic Se n (n = 3-12) clusters have been systematically investigated using conventional ab initio [HF, MP2, MP3, MP4, CCSD, CCSD(T)] and density functional theory (B3LYP, CAM-B3LYP) levels with the Dunning's correlation-consistent (cc-pVDZ, aug-cc-pVDZ, d-aug-ccpVDZ and aug-cc-pVTZ) and Sadlej (POL and POL-DK) basis sets. For each cluster size, various structural isomers have been considered and optimized to search for the lowest-energy structure. The effects of the geometry, basis set and theoretical level on the calculated properties have been discussed. The relative stability of the clusters has been analyzed using binding energy per atom, D 2 E and VIE-VEA gap. The computed binding energies and VIEs have been compared with the available observed data. The calculated properties show a strong dependence upon the size and geometry of the cluster. The even-numbered Se n with n = 6 and 8 are predicted to be relatively stable clusters. The physico-chemical properties of selenium clusters have been compared to those of the sulphur homologues. On passing from sulphur to selenium clusters the binding energy per atom decreases, whereas the mean dipole polarizability per atom increases.

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Raman and absorption spectra of the zeolites A and X containing selenium and tellurium in the nanopores

Cited by 29 publications

References 8 publications

Structure of selenium clusters in the framework of zeolite Nd-Y

Structure of selenium clusters in the framework of zeolite Nd-Y

Raman spectroscopy of optical phonon confinement in nanostructured materials

Structural, energetic and response electric properties of cyclic selenium clusters: an ab initio and density functional theory study

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