Second-Order Raman Spectra of Fluorites. I. Critical Point Analysis

1972 ◽  
Vol 50 (8) ◽  
pp. 849-857 ◽  
Author(s):  
N. Krishnamurthy ◽  
V. Soots
Keyword(s):  
Critical Point ◽  
Single Crystals ◽  
Raman Spectra ◽  
Brillouin Zone ◽  
Critical Points ◽  
Photon Counting ◽  
Second Order ◽  
Selection Rules ◽  
Point Analysis ◽  
Critical Point Analysis

With the use of a high-powered Ar+ laser and conventional photon counting techniques it has been possible to observe the second-order Raman spectra of single crystals of CaF2, SrF2, BaF2, and PbF2. The symmetries of the various parts of the spectra of the latter two were determined by using oriented single crystals of these two fluorides. The main features of the observed spectra have been analyzed, with the aid of group-theoretical selection rules, in terms of calculated phonon frequencies at the critical points of the Brillouin zone of these crystals.

Critical point analysis of cubic ZnS

1970 ◽  
Vol 48 (21) ◽  
pp. 2477-2480 ◽  
Author(s):  
J. C. Irwin
Keyword(s):  
Theoretical Model ◽  
Critical Point ◽  
Infrared Spectra ◽  
Critical Points ◽  
Second Order ◽  
Experimental Results ◽  
Zone Boundary ◽  
Point Analysis ◽  
Critical Point Analysis

An interpretation of the second-order Raman and infrared spectra of cubic ZnS is given. A set of values is obtained for the phonon frequencies at the zone boundary critical points X, L, and W. These values are consistent with both the experimental results and a theoretical model. The frequencies obtained are compared with those proposed by previous workers.

Phonon Dispersion in ZnSe

1972 ◽  
Vol 50 (21) ◽  
pp. 2596-2604 ◽  
Author(s):  
J. C. Irwin ◽  
J. LaCombe
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Specific Heat ◽  
Single Crystals ◽  
Raman Spectra ◽  
Density Of States ◽  
Brillouin Zone ◽  
Critical Points ◽  
Phonon Dispersion ◽  
Zone Boundary

Second-order Raman spectra have been obtained from oriented single crystals of ZnSe. The spectra have been interpreted and the results have been used to determine the zone boundary frequencies at the critical points X, L, and W. The resulting set of frequencies are consistent with known polarization selection rules and with a theoretical model. The frequencies in turn serve to determine the parameters in the theoretical model and the resulting model has been used to calculate the phonon dispersion throughout the Brillouin zone, the density of states, and the specific heat. The results are compared to the small amount of experimental data that is available.

scholarly journals The emergent diseases in grapevine nursery: Critical point analysis for developing a protected and sustainable propagation process

2019 ◽  
Vol 15 ◽  
pp. 01026
Author(s):  
E. Battiston ◽  
S. Di Marco ◽  
E. Angelini ◽  
L. Mugnai
Keyword(s):  
Critical Point ◽  
Economic Impact ◽  
Environmental Sustainability ◽  
Plant Diseases ◽  
Propagation Process ◽  
Point Analysis ◽  
Propagation Material ◽  
Critical Point Analysis

The diffusion of emergent pathogens in grapevine nursery is increasingly compromising the sanitary quality of the propagation material. The complexity of the problem lies on the plurality of plant diseases involved and on the high environmental and economic impact of the conventional methods applied to comply the phytosanitary standards. By a critical point analysis, the study suggests the development of nursery strategies focused on the sanitary quality of the production and on its long-term environmental sustainability.

New Developments in Raman Spectroscopy with Lasers: Electronic Transitions

1968 ◽  
Vol 22 (5) ◽  
pp. 438-444 ◽  
Author(s):  
J. A. Koningstein
Keyword(s):  
Raman Spectroscopy ◽  
Single Crystals ◽  
Crystal Field ◽  
Raman Spectra ◽  
Raman Effect ◽  
Electronic Transitions ◽  
New Developments ◽  
Selection Rules ◽  
Phonon Spectra ◽  
Host Lattices

A discussion is given of the Raman spectra of single crystals of yttrium gallium garnet (YGaG), of ytterbrium gallium garnet (YbGaG), and of Yb:YGaG. From a comparison of the spectra it has been possible to separate the phonon spectra of the host lattices from that of an electronic Raman effect which occurs between the crystal field levels of the 2F7/2 manifold of Yb3+ in the garnet crystals. Information with respect to the selection rules governing both types of spectra is given.

scholarly journals Critical-Point Analysis For Three-Variable Cancer Angiogenesis Models

2005 ◽  
Vol 2 (3) ◽  
pp. 511-525 ◽  
Author(s):  
Urszula Foryś ◽  
◽  
Yuri Kheifetz ◽  
Yuri Kogan ◽  
Keyword(s):  
Critical Point ◽  
Point Analysis ◽  
Critical Point Analysis
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