Infrared band shape and intensity studies on molecular motions and interactions in condensed phases. Part 2.—Effects of vibrational relaxation and collisional broadening on the spectra of ICl and IBr in benzene and cyclohexane

1975 ◽  
Vol 71 (0) ◽  
pp. 714-727 ◽  
Author(s):  
Jack Yarwood
Keyword(s):  
Vibrational Relaxation ◽  
Condensed Phases ◽  
Molecular Motions ◽  
Infrared Band ◽  
Band Shape ◽  
Collisional Broadening

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.

Studies of molecular motions and vibrational relaxation in acetonitrile

1979 ◽  
Vol 38 (3) ◽  
pp. 699-716 ◽  
Author(s):  
M.W. Evans ◽  
G.J. Evans ◽  
J. Yarwood ◽  
P.L. James ◽  
R. Arndt
Keyword(s):  
Vibrational Relaxation ◽  
Molecular Motions

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
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