THE INFLUENCE OF DISORDER ON THE GROUP-THEORETICALLY DERIVED SELECTION-RULES IN AMMONIUM HALIDES

Date

1988-05-01

Author

Yurtseven, Hasan Hamit

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

107
views

0
downloads

There is no significant disagreement about the basic selection rules operating in the ferro-ordered (δ) and antiferro-ordered (γ) phases of the ammonium halides. The effects of residual disorder just below the transition temperature (Tc) are still treated differently by different research groups and therefore this remains a subject of some interest. In this study it will be shown how our approaches lead to assignments of the modes observed in the disordered β - phase, Raman spectrum at temperatures just below Tc will be discussed. The self-consistancy of the various possible approaches to this problem will be shown.

Subject Keywords

Chemistry, Physical

URI

https://hdl.handle.net/11511/57456

Journal

JOURNAL OF MOLECULAR STRUCTURE

DOI

https://doi.org/10.1016/s0022-2860(98)80120-8

Collections

Department of Physics, Article

Suggestions

OpenMETU
Core

GENERAL THERMODYNAMIC TREATMENT OF AMMONIUM-CHLORIDE SYSTEM CLOSE TO PHASE-TRANSITIONS Yurtseven, Hasan Hamit (1986-03-01) In ammonium halides the optical and acoustical phonons may be represented by the Einstein and Debye models. Close to the λ-phase-transition, the model for the lattice vibrations in these crystals requires an extra component which can be described by an Ising model. In this study we have developed an Ising model superimposed on an Einstein and/or Debye model and have applied it to the NH4Cl system. In this application we have used the Raman frequency of the ν5(174cm−1) phonon of NH4Cl to characterize the cor...
Synthesis, characterization, and catalytic activity of supported molybdenum Schiff base complex as a magnetically recoverable nanocatalyst in epoxidation reaction Moradi-Shoeili, Zeinab; Zare, Maryam; Bagherzadeh, Mojtaba; Özkar, Saim; Akbayrak, Serdar (Informa UK Limited, 2016-01-01) A heterogeneous nanocatalyst was prepared via covalent anchoring of dioxomolybdenum(VI) Schiff base complex on core-shell structured Fe3O4@SiO2. The properties and the nature of the surface-fixed complex have been identified by a series of characterization techniques such as SEM, EDX, XRD, TGA, FT-IR, and VSM. The synthesized hybrid material was an efficient nanocatalyst for selective oxidation of olefins to corresponding epoxides with t-BuOOH in high yields and selectivity. The catalyst could be convenient...
The positional effect of dodecagonal holes on C-56 structure Türker, Burhan Lemi (Elsevier BV, 2004-05-14) Some C-56 isomers obtained theoretically from C-60 structure by deleting two C-2 units and bonds adjacent to those have been subjected to AM1 (UHF) type semiempirical quantum chemical calculations. Positional effects of dodecagonal (cyclododecahexaene rings) holes on the stabilities are discussed in the case of neutral as well as monovalent cationic form of these species which are all stable but endothermic in nature.
An asymmetric synthesis of both enantiomers of 2,2,2-trifluoro-1-furan-2-yl-ethylamine and 3,3,3-trifluoroalanine from 2,2,2-trifluoro-1-furan-2-yl-ethanone Demir, Ayhan Sıtkı; Sesenoglu, O; Gercek-Arkin, Z (Elsevier BV, 2001-09-13) The selective conversion of 2,2,2-trifluoro-1-furan-2-yl-ethanone into (E)- and (Z)-oximes and oxime ethers and subsequent oxazaborolidine-catalyzed enantioselective reduction using different amino alcohols furnished both enantiomers of the important chiral building block 2,2,2-trifluoro-1-furan-2-yl-ethylamine with e.e. of up to 88%. Oxidation of the furan ring afforded both enantiomers of 3,3,3-trifluoroalanine in 91-93% yields.
CHARACTERIZATION OF SILICA CATALYST SUPPORTS BY SINGLE AND MULTIPLE-QUANTUM PROTON NMR-SPECTROSCOPY HWANG, SJ; Üner, Deniz; KING, TS; PRUSKI, M; GERSTEIN, BC (American Chemical Society (ACS), 1995-03-16) Cab-O-Sil HS5, used as the support in silica supported ruthenium (Ru/SiO2) catalysts, was characterized via single and multiple quantum (MQ) H-1 NMR spectroscopy. The samples were studied both in the presence and in the absence of ruthenium. Single quantum spin counting of protons on silica support with and without ruthenium metal indicated that the total number of hydroxyl groups decreased significantly with increasing reduction temperature over the range of 350-530 degrees C. Two different components show...

Citation Formats

H. H. Yurtseven, “THE INFLUENCE OF DISORDER ON THE GROUP-THEORETICALLY DERIVED SELECTION-RULES IN AMMONIUM HALIDES,” JOURNAL OF MOLECULAR STRUCTURE, pp. 459–464, 1988, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/57456.