Energy transfer in polyatomic molecules. II. Relative catalytic efficiency for energy transfer to different vibrations to the same molecule

1961 ◽  
Vol 264 (1318) ◽  
pp. 299-308 ◽  
Keyword(s):  
Energy Transfer ◽  
Sulphur Dioxide ◽  
Deuterium Oxide ◽  
Relaxation Times ◽  
Catalytic Efficiency ◽  
Polyatomic Molecules ◽  
Fair Agreement ◽  
Water Molecules ◽  
Relaxation Processes ◽  
Ultrasonic Measurements

Vibrations of sulphur dioxide show two separate relaxation times. Values of r 1 = 6.0 × 10 -8 s for the vibrations of 519 cm -1 and r 2 = 1.2 × 10 -6 s for the vibrations of 1151 and 1361 cm -1 have been derived from new ultrasonic measurements, in fair agreement with earlier work. Molecules studied as possible vibration-translation catalysts included ethane, ethylene, water, and n -hexane. No enhanced efficiency of energy transfer was observed with ethylene. Ethane and water molecules were found to be only moderately efficient catalysts; proportionally, they exert a greater effect for processes associated with r 1 . Deuterium oxide is found to be somewhat more efficient than water. n -Hexane is highly efficient for both the r 1 and r 2 relaxation processes of sulphur dioxide. These observations are discussed in relation to various mechanisms for the catalysis of energy transfer.

Energy transfer in polyatomic molecules I. Catalysis of energy transfer with isotopic molecules

1961 ◽  
Vol 264 (1318) ◽  
pp. 289-298 ◽  
Keyword(s):  
Energy Transfer ◽  
Vibrational Mode ◽  
General Trend ◽  
Relaxation Times ◽  
Polyatomic Molecules ◽  
Higher Modes ◽  
Quantitative Account ◽  
Rate Of Activation

Dispersion of sound has been com pared for ethylene and tetradeutero-ethylene. Relaxation times of 0.26 and 0.14 u s for these molecules follow the general trend with molecular frequencies predicted by theory. A quantitative account of th e observed ratio 1:2 of relaxation times can best be given by introducing the notion of ‘complex collisions’ and by abandoning the concept that the rate of activation of the lowest vibrational mode fully controls the rate of activation of higher modes. Small amounts of C 2 D 4 or C 2 D 2 H 2 act as energy transfer catalysts for ethylene. Both H 2 O and D 2 O likewise act as catalysts, approximately to the same extent. Theoretical interpretations of these findings are discussed.

Temperature dependence of vibrational relaxation times in gases

1958 ◽  
Vol 244 (1237) ◽  
pp. 212-219 ◽  
Keyword(s):  
Energy Transfer ◽  
Methyl Bromide ◽  
Sulphur Dioxide ◽  
Vibrational Relaxation ◽  
Transition Probability ◽  
Relaxation Times ◽  
Methyl Chloride ◽  
Collision Theory ◽  
Ultrasonic Dispersion ◽  
Carbon Tetrafluoride

Ultrasonic dispersion measurements at varying temperatures, extending over the range 290 to 580° K, have been made on gaseous ethylene, cyclo propane, carbon tetrafluoride, methyl chloride and methyl bromide. The results are correlated with previous measurements on methyl fluoride and sulphur dioxide. The non-polar gases show a steady rise in the probability of energy transfer between translation and vibration with rise in temperature. The transition probability, P 10 , is found to vary with exp — T -½ in accordance with current collision theory, but the quantitative dependence cannot be predicted from molecular properties. The polar gases behave in a similar way at higher temperatures, but at lower temperatures the transition probability increases with falling temperature. This is interpreted as due to increasing predominance of oriented collisions, which are specially favourable for energy transfer, between polar molecules at lower temperatures.

scholarly journals Activating cement mixing water with the relaxation processes

2020 ◽  
Vol 8 (4) ◽  
pp. 43-48
Author(s):  
Andrei Pavlov ◽  
Yurii Gol'tsov ◽  
Levon Mailyan ◽  
Evgeniy Shcherban' ◽  
Sergey Stel'makh ◽  
...  
Keyword(s):  
Relaxation Times ◽  
Free Water ◽  
Water Molecules ◽  
Relaxation Processes ◽  
Activity Time ◽  
Thermodynamically Equilibrium ◽  
Melt Water ◽  
Radiation Activation ◽  
The Common ◽  
Mixing Water

The analysis of relaxation processes in water activated by thermal or ultraviolet radiation has been carried out. The activation of the mixing water leads to an earlier hardening of the cement. At the same time, activated water loses its properties with a relaxation time, which is equal to the activity time of melt water, which is explained by the common reasons for the origin of the increased reaction properties of activated water and melt water. These properties are due to the fact that activation increases the content of free water molecules. In the normal state, some of the water molecules enter the voids of fractal-clathrate structures. During thermal or radiation activation processes, characterized by certain relaxation times, these structures are destroyed, and free water molecules are released. But after the termination of activation, relaxation processes take place to restore thermodynamically equilibrium fractal-clathrate structures, and part of the free water is again captured by these structures. Therefore, the reactivity of water after the termination of activation decreases.

Notizen:Kernmagnetische Relaxationszeit-Messungen an OH-Protonen einer kristallinen Kieselsäure/ Nuclear Magnetic Relaxation Measurements on the OH-Protons of a Crystalline Silicic Acid

1975 ◽  
Vol 30 (10) ◽  
pp. 1330-1332 ◽  
Author(s):  
E. K.-H. Wittich ◽  
J. Voitländer ◽  
G. Lagaly
Keyword(s):  
Thermal Decomposition ◽  
Silicic Acid ◽  
Magnetic Relaxation ◽  
Interlayer Space ◽  
Relaxation Times ◽  
Water Molecules ◽  
Relaxation Processes ◽  
Relaxation Measurements ◽  
Silicate Layers ◽  
Crystalline Silicic Acid

Abstract The transversal relaxation times of the OH-protons of a crystalline silicic acid were measured. Two relaxation processes, clearly separated from each other, are related to the OH-protons in the silicate layers and to the OH-protons of water molecules in the interlayer spaces. From the initial magnetizations information is obtained about the water content in the interlayer space which does well agree with results given in thermal decomposition curves.

Relaxation processes of some simple aliphatic molecules in dilute solutions

1977 ◽  
Vol 55 (4) ◽  
pp. 297-301 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Carbon Tetrachloride ◽  
Dielectric Relaxation ◽  
Thermodynamic Parameters ◽  
Relaxation Times ◽  
Relaxation Processes ◽  
Dilute Solutions ◽  
Microwave Region ◽  
Nonpolar Solvents ◽  
Dielectric Data ◽  
Intramolecular Rotation

The dielectric relaxation processes of acetone, cyclohexanone, 4-methyl-2-pentanone, and 4-heptanone in dilute nonpolar solvents, n-heptane, cyclohexane, benzene, and carbon tetrachloride have been studied in the microwave region over a temperature range 10 to 60 °C. The relaxation times and the thermodynamic parameters for the activated states have been determined using the measured dielectric data. The results have been discussed in terms of dipole reorientation by molecular and intramolecular rotation and compared, wherever possible, with other similar studies on aliphatic molecules.

Relaxation processes of quinoline, isoquinoline, and their mixtures

1980 ◽  
Vol 58 (1) ◽  
pp. 20-24 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Thermodynamic Parameters ◽  
Molecular Motion ◽  
Polar Solvent ◽  
Relaxation Times ◽  
Relaxation Processes ◽  
Polar Components ◽  
Dielectric Absorption ◽  
System A ◽  
Dielectric Data ◽  
Activated State

The dielectric absorption of quinoline, isoquinoline, and their binary mixtures has been studied in the microwave region over a range of temperatures in dilute benzene and n-heptane solutions. The relaxation times and the thermodynamic parameters for the activated state have been determined using the measured dielectric data. The results obtained have been discussed in terms of the molecular motion of the system. A relation has been proposed to represent the relaxation behavior of a system of two Debye-type polar components in a non-polar solvent. The relation has been tested by comparing the calculated values with those determined experimentally for a few systems consisting of similar, simple rigid polar molecules.

Temperature Dependence of Dynamic Properties of Elastomers. Relaxation Distributions

1952 ◽  
Vol 25 (4) ◽  
pp. 720-729 ◽  
Author(s):  
John D. Ferry ◽  
Edwin R. Fitzgerald ◽  
Lester D. Grandine ◽  
Malcolm L. Williams
Keyword(s):  
Distribution Function ◽  
Temperature Dependence ◽  
Dynamic Properties ◽  
Relaxation Times ◽  
Dynamic Mechanical Properties ◽  
Relaxation Processes ◽  
The Real ◽  
Reduced Frequency ◽  
Dynamic Rigidity ◽  
Composite Curve

Abstract By the use of reduced variables, the temperature dependence and frequency dependence of dynamic mechanical properties of rubberlike materials can be interrelated without any arbitrary assumptions about the functional form of either The definitions of the reduced variables are based on some simple assumptions regarding the nature of relaxation processes. The real part of the reduced dynamic rigidity, plotted against the reduced frequency, gives a single composite curve for data over wide ranges of frequency and temperature; this is true also for the imaginary part of the rigidity or the dynamic viscosity. The real and imaginary parts of the rigidity, although independent measurements, are interrelated through the distribution function of relaxation times, and this relation provides a check on experimental results. First and second approximation methods of calculating the distribution function from dynamic data are given. The use of the distribution function to predict various types of time-dependent mechanical behavior is illustrated.

Estimation in vivo of the chemical composition of the bodies of mature cows

1984 ◽  
Vol 38 (1) ◽  
pp. 33-44 ◽  
Author(s):  
I. A. Wright ◽  
A. J. F. Russel
Keyword(s):  
Body Composition ◽  
Body Fat ◽  
Body Condition ◽  
Body Condition Score ◽  
Deuterium Oxide ◽  
Subcutaneous Fat ◽  
Live Weight ◽  
Eye Muscle ◽  
Ultrasonic Measurements ◽  
Condition Score

ABSTRACTA number of possible indices of body composition (live weight, skeletal size, total body water as estimated by deuterium oxide dilution, blood and red cell volumes as estimated by Evans Blue dilution, ultrasonic measurements of subcutaneous fat depth and eye-muscle area, and body condition scoring) was examined using 73 non-pregnant, non-lactating, mature cows of Hereford × Friesian, Blue-Grey, British Friesian, Galloway and Luing genotypes, ranging in body condition score from 0·75 to 4·5. Direct measurements of body composition in terms of water, fat, protein and ash were made following slaughter.Live weight, deuterium oxide dilution, ultrasonic measurements of subcutaneous fat depth and eyemuscle area, and body condition score were all considered to be potentially useful predictors of body composition. Combinations of techniques offered better predictions than did any single index. Using a combination of measurements it was possible to predict body fat and protein with a residual s.d. of 13·1 kg and 3·15 kg respectively. Breed differences in the partition of fat among the main adipose tissue depots necessitated the development of specific prediction equations for body fat based on condition score and subcutaneous fat depth for different breeds. Equations remain to be developed for predicting body composition in cows in different physiological states.

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