Infrared band shape and intermolecular interactions studied on the Sih valence vibration of organosilanes

1984 ◽  
Vol 114 ◽  
pp. 143-150 ◽  
Author(s):  
A. Reklat ◽  
H. Kriegsmann
Keyword(s):  
Intermolecular Interactions ◽  
Valence Vibration ◽  
Infrared Band ◽  
Band Shape

Infrared Band-Shape Studies of Sulphate Glasses

1982 ◽  
Vol 37 (2) ◽  
pp. 191-195
Author(s):  
H. G. K. Sundar ◽  
R. Parthasarathy ◽  
K. J. Rao
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Shape Analysis ◽  
Cluster Model ◽  
Deformation Band ◽  
Infrared Band ◽  
Band Shape ◽  
Correlation Times ◽  
Second Moments

Abstract IR band-shape analysis has been carried out on the 620 cm-1 deformation band of the sulphate ion in several Na2SO4-K2SO4-ZnSO4 glasses. Variations of correlation times and second moments suggest that reorientational motions of sulphate ions begin to evolve prior to the glass-transition temperature. The correlation times may support a cluster model for the glass-transition.

A COMPARISON OF OPTIMIZATION METHODS FOR FITTING CURVES TO INFRARED BAND ENVELOPES

1966 ◽  
Vol 44 (24) ◽  
pp. 3031-3050 ◽  
Author(s):  
J. Pitha ◽  
R. Norman Jones
Keyword(s):  
Least Squares ◽  
Computation Time ◽  
Direct Methods ◽  
Nonlinear Least Squares ◽  
Optimization Methods ◽  
Infrared Band ◽  
Band Shape ◽  
Analytical Functions ◽  
Degree Of Convergence ◽  
Better Than

A comparison has been made of seven numerical methods of fitting infrared absorption band envelopes with analytical functions using nonlinear least squares approximations. Gauss and Cauchy (Lorentz) band shape functions are used, and also sum and product combinations of the two. The methods have been compared with respect to both the degree of convergence and to the computation time needed to achieve an acceptable fit.The most effective method has matched the overlap envelope of a steroid spectrum containing 16 bands; this necessitated the optimization of 65 variables. More complex spectra can be dealt with by a "moving subspace" modification in which only the parameters of a group of adjacent bands are adjusted at one time. Automatic computer programs have been written for five of the methods, and for the moving subspace modification. These will be published elsewhere.If the computed curve is convoluted with the spectral slit function before making the least squares calculations, the distortion of the observed spectrum caused by the finite spectral slit width can be corrected. In some cases this method of diminishing the slit distortion is better than direct methods, particularly when dealing with strongly overlapped bands.

scholarly journals Infrared Band Shape of the C–I Stretching Vibration of Methyl Iodide in Solutions

1975 ◽  
Vol 48 (12) ◽  
pp. 3464-3468 ◽  
Author(s):  
Kenji Fujiwara ◽  
Kohji Fukushi ◽  
Shun-ichi Ikawa ◽  
Masao Kimura
Keyword(s):  
Methyl Iodide ◽  
Infrared Band ◽  
Band Shape ◽  
Stretching Vibration

Size distribution of self assembled Ge nanocrystals determined by photoluminescence

2008 ◽  
Vol 1145 ◽  
Author(s):  
Nelson Rowell ◽  
David Lockwood ◽  
Isabelle Berbezier ◽  
Pierre David Szkutnik ◽  
Antoine Ronda
Keyword(s):  
Size Distribution ◽  
Near Infrared ◽  
Tight Binding ◽  
Theoretical Models ◽  
Theoretical Description ◽  
Infrared Band ◽  
Band Shape ◽  
Transmission Electron Microscopy Analysis ◽  
Electron Microscopy Analysis

AbstractGermanium nanocrystals (NCs) were formed by in-situ thermal annealing of an amorphous Ge layer deposited by molecular beam epitaxy on a thin SiO2 layer on Si(001). The Ge NCs were then capped in situ with a thin layer of amorphous Si to prevent oxidation. For the present range of particle sizes (2.5 to 60 nm), the NC photoluminescence (PL) appeared primarily as a wide near-infrared band peaked near 800 meV. The peak energy of the PL band reflects the average NC size and its shape depends on the NC size distribution. Using both the k·p and tight binding theoretical models, we have analyzed the PL spectrum in terms of the NC size distribution required to reproduce the observed asymmetric band shape, which includes, for the smaller diameter NCs, a band gap enlargement due to quantum confinement. The observed size distribution determined from transmission electron microscopy analysis allowed the determination of the nonlinear increase in the PL quantum efficiency with decreasing NC diameter. This implies that, given a good theoretical description of the system, it is possible to evaluate the size distribution of semiconductor NCs from their PL energy dependence.

Molecular orientational motions in liquid crystals: A study by Raman and infrared band-shape analysis

1986 ◽  
Vol 33 (6) ◽  
pp. 4132-4142 ◽  
Author(s):  
M. P. Fontana ◽  
B. Rosi ◽  
N. Kirov ◽  
I. Dozov
Keyword(s):  
Liquid Crystals ◽  
Shape Analysis ◽  
Infrared Band ◽  
Band Shape
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