Alignment tolerances for off-plane reflection grating spectroscopy: theoretical calculations and laboratory techniques

2013 ◽  
Author(s):  
Ryan Allured ◽  
Benjamin D. Donovan ◽  
Randall McEntaffer
Keyword(s):  
Theoretical Calculations ◽  
Laboratory Techniques ◽  
Grating Spectroscopy ◽  
Reflection Grating

RESONANCES IN THE SMITH–PURCELL EFFECT

1964 ◽  
Vol 42 (6) ◽  
pp. 1195-1211 ◽  
Author(s):  
A. Hessel
Keyword(s):  
Millimeter Waves ◽  
Current Sheath ◽  
Rigorous Solution ◽  
Resonance Effects ◽  
Optical Reflection ◽  
Electromagnetic Resonance ◽  
Optical Grating ◽  
Surface Reactance ◽  
Grating Spectroscopy ◽  
Reflection Grating

A rigorous solution is derived for the problem of radiation of the Smith–Purcell type (Smith and Purcell 1953) extracted from a radio-frequency bunched electric-current sheath, above a plane exhibiting a periodically varying surface reactance. The plane is regarded as a model of an optical reflection grating. The solution indicates that the presence of the grating will give rise to electromagnetic resonance effects which are closely related to the so-called Wood anomalies (Wood 1935; Twersky 1956; Hessel 1960; Hessel and Oliner 1962; Stewart and Gallaway 1962), encountered in optical-grating spectroscopy. Utilization of these resonances may be advantageous in the generation of millimeter waves.

scholarly journals Analytical alignment tolerances for off-plane reflection grating spectroscopy

2013 ◽  
Vol 36 (3) ◽  
pp. 661-677 ◽  
Author(s):  
Ryan Allured ◽  
Randall T. McEntaffer
Keyword(s):  
Grating Spectroscopy ◽  
Reflection Grating

XUV Absorption Spectra of Carbon Ions

1988 ◽  
Vol 102 ◽  
pp. 71-73
Author(s):  
E. Jannitti ◽  
P. Nicolosi ◽  
G. Tondello
Keyword(s):  
Absorption Spectra ◽  
Cross Section ◽  
Theoretical Calculations ◽  
Photoionization Cross Section ◽  
Carbon Ions

AbstractThe photoabsorption spectra of the carbon ions have been obtained by using two laser-produced plasmas. The photoionization cross-section of the CV has been absolutely measured and the value at threshold, σ=(4.7±0.5) × 10−19cm2, as well as its behaviour at higher energies agrees quite well with the theoretical calculations.

Relative Intensities in ED Patterns From Thin Gold Films

1972 ◽  
Vol 30 ◽  
pp. 636-637
Author(s):  
R. H. Morriss ◽  
J. D. C. Peng ◽  
C. D. Melvin
Keyword(s):  
Theoretical Calculations ◽  
Diffraction Theory ◽  
Gold Films ◽  
Reasonable Accuracy ◽  
Experimental Conditions ◽  
Crystal Perfection ◽  
Heavy Atoms ◽  
Fine Focus ◽  
Convergent Beam ◽  
Beam Diffraction

Although dynamical diffraction theory was modified for electrons by Bethe in 1928, relatively few calculations have been carried out because of computational difficulties. Even fewer attempts have been made to correlate experimental data with theoretical calculations. The experimental conditions are indeed stringent - not only is a knowledge of crystal perfection, morphology, and orientation necessary, but other factors such as specimen contamination are important and must be carefully controlled. The experimental method of fine-focus convergent-beam electron diffraction has been successfully applied by Goodman and Lehmpfuhl to single crystals of MgO containing light atoms and more recently by Lynch to single crystalline (111) gold films which contain heavy atoms. In both experiments intensity distributions were calculated using the multislice method of n-beam diffraction theory. In order to obtain reasonable accuracy Lynch found it necessary to include 139 beams in the calculations for gold with all but 43 corresponding to beams out of the [111] zone.

Effects of Higher-Order Laue Zone reflections on structure images

1993 ◽  
Vol 51 ◽  
pp. 450-451
Author(s):  
H. S. Kim ◽  
S. S. Sheinin
Keyword(s):  
Wave Vector ◽  
Theoretical Calculations ◽  
Reciprocal Lattice ◽  
Image Plane ◽  
Bloch Wave ◽  
Dynamical Theory ◽  
Higher Order ◽  
Lattice Image ◽  
Lattice Vector ◽  
Image Position

The importance of image simulation in interpreting experimental lattice images is well established. Normally, in carrying out the required theoretical calculations, only zero order Laue zone reflections are taken into account. In this paper we assess the conditions for which this procedure is valid and indicate circumstances in which higher order Laue zone reflections may be important. Our work is based on an analysis of the requirements for obtaining structure images i.e. images directly related to the projected potential. In the considerations to follow, the Bloch wave formulation of the dynamical theory has been used.The intensity in a lattice image can be obtained from the total wave function at the image plane is given by: where ϕg(z) is the diffracted beam amplitide given by In these equations,the z direction is perpendicular to the entrance surface, g is a reciprocal lattice vector, the Cg(i) are Fourier coefficients in the expression for a Bloch wave, b(i), X(i) is the Bloch wave excitation coefficient, ϒ(i)=k(i)-K, k(i) is a Bloch wave vector, K is the electron wave vector after correction for the mean inner potential of the crystal, T(q) and D(q) are the transfer function and damping function respectively, q is a scattering vector and the summation is over i=l,N where N is the number of beams taken into account.

The Adaptation of Medical Records to Epidemiological Use

1965 ◽  
Vol 04 (03) ◽  
pp. 136-140
Author(s):  
Cl Jeanty
Keyword(s):  
Medical Records ◽  
Clinical Pathology ◽  
Time Variable ◽  
Special Care ◽  
General Description ◽  
Causal Relations ◽  
Laboratory Techniques ◽  
Original Record ◽  
Statistical Studies

A method is described in an attempt to make medical records suitable for epidemiologigri: purposes. Every case of a disease is recorded on an appropriate punched card with the object of working towards a general description of a disease through the collation of several cases of the same diagnosis. This punched card represents a very great condensation of the original record. Special care has been applied to state as precisely as possible the time variable, particularly as far as its origin and unit of measure are concerned, in order to demonstrate the existence of causal relations between diseases. Such cards are also intended to make easier statistical studies in clinical pathology, in evaluation of new laboratory techniques, and in therapeutical trials.

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