Studies on rotational barriers in alkyl halogenides by means of vibrational spectroscopy

1980 ◽  
Vol 45 (4) ◽  
pp. 984-996 ◽  
Author(s):  
Michal Bureš ◽  
Čestmír Černý
Keyword(s):  
Simple Model ◽  
Internal Rotation ◽  
Infrared Spectra ◽  
Conformational Transitions ◽  
Gaseous State ◽  
Rotational Barriers ◽  
Halogenated Alkanes ◽  
Kinetics Of ◽  
The Ideal ◽  
Ideal Gaseous State

A simple model describing the influence of the neighbouring molecules on the mechanism of the internal rotation in a given molecule has been proposed which allows the calculation of the barrier hindering the internal rotation in the ideal gaseous state from the temperature dependencyof the infrared spectra. To ascertain its adequacy, the kinetics of conformational transitions in seven halogenated alkanes has been investigated, and values of the activation enthalpies accompanying the internal rotation in a solution as well as the rotational barriers in the ideal gaseous state have been determined.

Equilibria in the transport epitaxial formation of indium phosphide and arsenide

1986 ◽  
Vol 51 (6) ◽  
pp. 1213-1221 ◽  
Author(s):  
Ivo Braun ◽  
Přemysl Klíma ◽  
Josef Stejskal ◽  
Čestmír Černý ◽  
Petr Voňka ◽  
...  
Keyword(s):  
Indium Phosphide ◽  
Indium Arsenide ◽  
Theoretical Calculations ◽  
Equilibrium Mixture ◽  
Pure Liquid ◽  
Gaseous State ◽  
First Case ◽  
Other Substances ◽  
The Ideal ◽  
Ideal Gaseous State

From the data available in literature, equilibria were calculated of the reactions which come into consideration in the preparation of indium phosphide and indium arsenide. In the first case it was supposed that indium phosphide was formed as a pure solid substance, that indium might exist either as a pure liquid, or as a gas and that the remaining 16 components in the equilibrium mixture were in the ideal gaseous state. In the second case, the formation of pure solid indium arsenide and the existence of 18 other substances in the equilibrium mixture, also in the ideal gaseous state, were supposed. The results of these theoretical calculations for indium phosphide were compared with the experimental deposition temperatures and reasonable agreement has been found.

Description of a Simple Model for the Study of Bone Calcium Metabolism

1980 ◽  
Vol 19 (01) ◽  
pp. 11-15
Author(s):  
G. Roncari ◽  
L. Rapisardi ◽  
L. Conte ◽  
G. Pedroli
Keyword(s):  
Simple Model ◽  
Calcium Metabolism ◽  
Good Description ◽  
Radioactive Tracer ◽  
Normal Subjects ◽  
Bone Diseases ◽  
Compartment System ◽  
Bone Calcium ◽  
Finite Period ◽  
Kinetics Of

A simple model for the study of bone calcium metabolism is proposed. It describes the kinetics of a radioactive tracer in terms of an open single compartment system with an expanding volume for a finite period of time. In addition to the simplicity of the hypotheses introduced, the model is able to give a good description of the biological processes which regulate calcium kinetics. Moreover the functional parameters can be easily calculated, even just graphically. 15 normal subjects and 22 patients affected by various bone diseases were studied. The results were compared with those obtained by using the model proposed by Burkinshaw et al. and the method described by Reeve et al.

scholarly journals Structural Parameters and Internal Rotational Barriers of tert-Butylammonium Ion: AM1 and ab initio Calculations

1992 ◽  
Vol 47 (12) ◽  
pp. 1255-1256
Author(s):  
Hiroyuki Ishida ◽  
Yoshihiro Kubozono ◽  
Setsuo Kashino ◽  
Ryuichi Ikeda
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Internal Rotation ◽  
Barrier Height ◽  
Structural Parameters ◽  
Mo Calculations ◽  
Ab Initio Mo Calculations ◽  
Rotational Barriers ◽  
Ab Initio Mo ◽  
Internal Rotational Barriers

Semiempirical and ab initio MO calculations were performed to estimate the structural parameters of tert-butylammonium ion and its potential energies for the internal rotation of the CH3 and NH3+ groups. The barrier height for the rotation of NH3+ was found to be lower than for that of CH3 , corresponding to the C - N bond being longer than the C - C bond.

A simple model describing the kinetics of the xanthophyll cycle

1991 ◽  
Vol 41 (2) ◽  
pp. 125-129 ◽  
Author(s):  
Jan Sielewiesiuk ◽  
Wiesław I. Gruszecki
Keyword(s):  
Simple Model ◽  
Xanthophyll Cycle ◽  
Kinetics Of

GROWTH OF OXIDE LAYER ON GERMANIUM (011) SUBSTRATE UNDER DRY AND WET ATMOSPHERES

1999 ◽  
Vol 06 (06) ◽  
pp. 1053-1060 ◽  
Author(s):  
N. TABET ◽  
J. AL-SADAH ◽  
M. SALIM
Keyword(s):  
Simple Model ◽  
Oxide Film ◽  
Growth Kinetics ◽  
Photoelectron Spectroscopy ◽  
Early Stage ◽  
X Ray ◽  
Apparent Thickness ◽  
Different Temperatures ◽  
Kinetics Of

X-ray Photoelectron Spectroscopy (XPS) has been used to investigate the oxidation of (011) Ge substrates. The sample surfaces were CP4-etched, then annealed in situ, at different temperatures, for various durations. Dry and wet atmospheres were used. The oxidation rate during the early stage was increased by the presence of moisture in the atmosphere. A simple model was used to define and determine an apparent thickness of the oxide film from XPS measurements. The time dependence of the apparent thickness is consistent with a partial coverage of the surface by oxide islands. The growth kinetics of the oxide islands obeys a nearly cubic law.

Studies on metal hydroxy compounds. X. Thermal analyses, decomposition kinetics, and infrared spectra of lead halide (Cl, Br, I) derivatives

1970 ◽  
Vol 48 (16) ◽  
pp. 2617-2622 ◽  
Author(s):  
P. Ramamurthy ◽  
E. A. Secco ◽  
M. Badri
Keyword(s):  
Infrared Spectra ◽  
Rate Equation ◽  
Thermal Analyses ◽  
Decomposition Reaction ◽  
Diffusion Type ◽  
Type Rate ◽  
Hydroxy Compounds ◽  
Kinetics Of ◽  
Lead Halide ◽  
Order Rate Equation

The thermal analyses, thermogravimetry (TG), and differential thermal analysis (DTA) of PbOHCl, PbOHBr, and PbOHI reveal that the initial mode of decomposition is via dehydroxylation. Calorimetric measurements along with related enthalpy values for the decomposition reaction are given.The infrared spectra of these compounds are interpreted in terms of folded bands of (PbOH+)n tied together by halide ions consistent with their crystal structures.The kinetics of thermal decomposition of lead hydroxyhalides follow a diffusion-type rate equation which is in contrast to the simple first-order rate equation observed for most Cd, Zn, and Cu compounds. These two distinct rates are interpreted in terms of mobile OH or H species in the dehydroxylation step.

Kinetics of Internal Rotation of N,N-Dimethylacetamide: A Spin-Saturation Transfer Experiment

1997 ◽  
Vol 74 (8) ◽  
pp. 978 ◽  
Author(s):  
Russell L. Jarek ◽  
Robert J. Flesher ◽  
Seung Koo Shin
Keyword(s):  
Internal Rotation ◽  
Saturation Transfer ◽  
Transfer Experiment ◽  
Kinetics Of
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