Chemical relaxation methods principles

Provided also that the concentration changes are small compared with the equilibrium concentrations the differential equations governing the approach to the new equilibrium can always be linearised such that the kinetic progress curves are exponential or the sums of exponentials. In principle, the number of relaxations which may be observed, equals the number of independent equilibria involved in the mechanism of the reaction. Each relaxation is characterised by a relaxation time (t) with (1/t) being equivalent to /c bs (see above). The theoretical basis of chemical relaxation has been extensively discussed by Eigen and de Maeyer [18] and the temperature jump method by Brunori [19]. In this section we will briefly illustrate some applications of temperature-jump methods to proteins and enzymes. 

Solid-state NMR magnetisation relaxation experiments provide a good method for the analysis of network structures. In the past two decades considerable progress has been made in the field of elastomer characterisation using transverse or spin-spin (T2) relaxation data [36-42]. The principle of the use of such relaxation experiments is based on the high sensitivity of the relaxation process to chain dynamics involving large spatial-scale chain motion in elastomers at temperatures well above the Tg and in swollen networks. Since chain motion is closely coupled to elastomer structure, chemical information can also be obtained in this way. 

Other experimental methods for obtaining chemical shift anisotropies are the spin-lattice relaxation, molecular beam, and clathrate methods. The spin-lattice relaxation time, T, measures how soon a nuclear spin or assemblage of spins returns to its equilibrium position by releasing eneigy to the total system. Any mechanism that provides a fluctuating magnetic field can, in principle, contain the proper Fourier... 

This book is divided into two parts the basic principles of solid state NMR and its application to polymer systems in the solid state. In the former part, the principles of NMR, important NMR parameters such as chemical shifts, relaxation times, dipolar interactions, quadrupolar interactions, pulse techniques and new NMR methods are covered. In the latter part, applications of NMR... 

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