This article couples chemical exchange to rotational relaxation in l~quids. W~ found that the relat!ve rates of exchange and molecular rotation have a profound effect on relaxatIon behaVIor. S~tet,ns exchangmg more slowly than the rate of molecular rotation can be distinguished from systems expenencmg faster exchange. This leads to a novel class of experiments using molecular rotation as a frequency ~tandard fo~ the ex~h~~ge process. Since rotational correlation times are typically 1O-10-1~12 sec. these exp.enment,s provIde senSltlVl.ty on a time scale not easily achieved by other techniques. AnalYSIS of these e~nmen.ts IS pre~nted. Studies of NMR spin-lattice relaxation in iodine charge-transfer complexes substantIate thIS analYSIS.

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Contents 1. Introduction . 2. Holography in general . 2.1. Theory , 2.2. General holographic techniques . 2.3. Holographic recording media . 2.4. Techniques for maximum light utilization 3.1. Theory , 3.2. The basic stroboscopic method and its uses . 3.3. Live and frozen fringe techniques. 3.4. Strobing techniques . 3.5. Advantages of the stroboscopic method 3.6. Disadvantages of the stroboscopic method 4.1. Theory .4.2. Advantages and disadvantages of the time-averaged method 4.3. Modifications . 4.4. An application of time-averaged holography. 5 . Alterations in sensitivity, and related methods . 5.1. Methods for increasing sensitivity . 5.2. Methods for reducing sensitivity . 5.3. Related methods of vibration analysis . 5.4. Conclusion..

By selecting particular types of currently available plastic coned miniature loudspeakers, and appropriately configuring each device with a suitable closed oscillatory circuit, it is possible to construct a liquid density transducer. Whereas current resonant densitometers operating in either the transverse, radial, torsional, or longitudinal resonance mode, are subject to relatively costly manufacturing and calibration procedures, the present development promises a very low-cost, easily calibrated, high-resolution [10−4] instrument with potentially very wide applications hitherto unavailable because of cost and size limitations. We show that this essentially simple apparatus embodies all the physical and operational requirements of established instruments.