Ionic Raman Effect. III. First- and Second-Order Ionic Raman Effects

1972 ◽  
Vol 6 (10) ◽  
pp. 3886-3897 ◽  
Author(s):  
L. B. Humphreys
Keyword(s):  
Raman Effect ◽  
Second Order

Second-Order Raman Effect in AlP, AlAs, and AlSb

1974 ◽  
pp. 509-513 ◽  
Author(s):  
H. Masui ◽  
P. B. Klein ◽  
R. K. Chang ◽  
R. H. Callender ◽  
R. J. Chicotka
Keyword(s):  
Raman Effect ◽  
Second Order

scholarly journals The theory of the Raman effect in crystals, in particular rock-salt

1947 ◽  
Vol 188 (1013) ◽  
pp. 161-178 ◽  
Keyword(s):  
Rock Salt ◽  
Lattice Dynamics ◽  
Raman Effect ◽  
Order Effect ◽  
Second Order ◽  
Coupling Constants ◽  
Combination Frequency ◽  
First Order ◽  
Combination Frequencies ◽  
Arbitrary Assumption

The Raman effect in crystals is treated in this paper with the help of Placzek’s approximation. It consists of contributions of different orders with respect to the amplitudes of the vibrations; the first-order effect is a line spectrum depending only on the vibrations of infinite wavelength, the second-order effect is a continuous spectrum depending on combination frequencies of all pairs of branches of the lattice vibrations, each pair taken for the same wave vector. In highly symmetrical crystals like rock-salt the first-order effect is zero. The second order effect can be calculated for rock-salt with the help of the tables of the lattice frequencies published by Kellermann. It consists of thirty-six peaks, each belonging to a combination frequency. The superposition of these allows us to determine without any arbitrary assumption about the coupling constants, the frequency of the observable maxima in fair agreement with Krishnan’s measurements. By adapting three coupling constants one can also determine the relative intensities of the most prominent peaks and obtain a curve which in its main features agrees with the observed one. The results show that lattice dynamics can account quantitatively for the Raman effect in crystals and that Raman’s attacks against the theory are unfounded.

Second-order Raman effect in alkaline earth oxides

1974 ◽  
Vol 7 (2) ◽  
pp. 439-444 ◽  
Author(s):  
M Buchanan ◽  
H Bilz ◽  
R Haberkorn
Keyword(s):  
Alkaline Earth ◽  
Raman Effect ◽  
Second Order

Disappearance Voltage Determinations Using a Convergent Beam

1971 ◽  
Vol 29 ◽  
pp. 184-185
Author(s):  
W. L. Bell
Keyword(s):  
Second Order ◽  
Objective Method ◽  
Uniform Thickness ◽  
Rocking Curve ◽  
Crystal Perfection ◽  
Kikuchi Line ◽  
Central Maximum ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Beam Technique

Disappearance voltages for second order reflections can be determined experimentally in a variety of ways. The more subjective methods, such as Kikuchi line disappearance and bend contour imaging, involve comparing a series of diffraction patterns or micrographs taken at intervals throughout the disappearance range and selecting that voltage which gives the strongest disappearance effect. The estimated accuracies of these methods are both to within 10 kV, or about 2-4%, of the true disappearance voltage, which is quite sufficient for using these voltages in further calculations. However, it is the necessity of determining this information by comparisons of exposed plates rather than while operating the microscope that detracts from the immediate usefulness of these methods if there is reason to perform experiments at an unknown disappearance voltage.The convergent beam technique for determining the disappearance voltage has been found to be a highly objective method when it is applicable, i.e. when reasonable crystal perfection exists and an area of uniform thickness can be found. The criterion for determining this voltage is that the central maximum disappear from the rocking curve for the second order spot.

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