Amplitude Modulation Techniques

Haar. R-P., and Hiuaer, M., 1978, Phase fluorometer for measurement of picosecond processes. Rev. Sd. Instrwn. 49 632-633. Ougger, H., and Caizaferri, O., 1979, Kcosecood time resolution by a continuous wave laser amplitude modulation technique U A critical investigation, J, Photodiem. 13 21-33. 

As in the case of ICN, two transitions were detected in the zf ODMR spectrum of IBN in durene using amplitude-modulation techniques. These are shown in Fig. 2A,B. However, unlike ICN, each of these transitions shows additional structure at low microwave power. The separations of the two components in each of the multiplets are 6.0 and 7.5 MHz, respectively. In addition, the higher frequency components of the two transitions are markedly broader than the lower frequency ones (FWHM/s, in order of increasing V, are 3.0, 15, 2.6, and 6.0 MHz), show pronounced high-frequency tails, and increase in intensity relative to the lower-frequency components with increasing power. Each of these transitions is also flanked by two pairs of satellite lines at high power (Fig. 2C,D). The third zf transition was detected at 2695 MHz using MIDP techniques. 

The ionization efficiency curves of both products and reactants obtained in this way should be equivalent to the same curves obtained by the electron-amplitude-modulation technique described above. 

Sideband suppression An amplitude modulation technique wherein one of the AM sidebands is deliberately suppressed, usually to conserve bandwidth. 

S. K. Misra, Microwave Amplitude Modulation Technique to Measure Spin-Lattice and Spin-Spin (T2) Relaxation Tunes , in Biological Magnetic Resonance, eds. C. J. Bender and L. J. Berliner, Springer, 2006, vol. 25, Computational and Instrumental Methods in EPR, p. 1. 

MICROWAVE AMPLITUDE MODULATION TECHNIQUE TO MEASURE SPIN-LATTICE (Ti) AND SPIN-SPIN Ti) RELAXATION TIMES... 

The purpose of this chapter is to review the amplitude modulation technique, address the limitations of the classic studies in the light of these reeent technological advances, and present equations that can be used to make predictions about both the EPR response in the z- and x,j-directions. 

Misra SK. 2005. Microwave amplitude modulation technique to measure spin-lattice relaxation times solution of Bloch s equations by a matrix technique. Appl Magn Reson 28 55-67. 

Chapters 1 deals with the important problem of measiuing spin relaxation times over a broad temporal range. The author. Dr. Sushil Misra, has worked on a wide variety of solutions to problems in this area, with respect to both experimental and theoretical aspects, and Chapter 1 summarizes much of his recent work, which was enhanced by a fruitful collaboration with the late Professor Jacques Pescia. Chapter 2 presents solutions to the problem of measiuing short spin relaxation times. Again, in collaboration and tribute to the late Jacques Peseta s laboratory, part of the chapter represents a translation of the amplitude modulation technique section from a doctoral thesis by Robert Lopez in 1993 to The Paul Sabatier University. Experimental data that appeared in the original thesis are placed at the end of subsections that correspond to the described technique. 

The chopper modulation approach is an amplitude modulation technique, which uses square wave as a carrier signal. It works by shifting the sensor signals to higher frequencies to suppress the l//noise. The demodulation of modulated sensor signal is required to recover the original signal [51,58], Offset and noise compensation should be performed for better performance [51,58],... 

A variation on the amplitude modulation technique was also used to measure oscillatory surface forces with increased sensitivity in a branched hydrocarbon, squalene. In this technique, the sample was oscillated with low amplitude (c. 1 A), and both the cantilever static and dynamic (induced oscillation from a change in the tip-sample force gradient) deflection was measured. Figure 1.13 shows the static force measurement and Fig. 1.14 the dynamic measurement, shown as an interaction stiffness. The sensitivity of the dynamic force measurement is such that the interdigitation of the branched methyl groups can be detected (indicated by arrows in Fig. 1.14). 

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