Wave interaction effects

The third principal category of effects is that of wave interaction, which arises from the interaction of the electromagnetic field of the incident radiation with the sensing material. The principal wave interaction effects are optical heterodyne detection and optical parametric effects. Among the others are effects at Josephson junctions and metal-metal oxide-metal contacts. These are listed in Table 2.5 and discussed below. 

Whether optical heterodyne detection should be classed as a wave interaction effect or a photon effect is not obvious. Because it depends upon the interaction of the electric field vector of the signal radiation with that from a reference source, it is listed here as a wave interaction effect. 

The excitation rate of free carriers in a semiconductor depends upon the rate of absorption of photons, which is a measure of the intensity of the absorbed radiation. Because the intensity is proportional to the square of the electric field vector, a photoconductor or a photovoltaic detector is a square law detector. Therefore, an alternative to the conventional way of viewing photoexcitation is that the semiconductor acts as a mixer element, beating the electric field vector against itself in a homodyne manner. Thus if two coherent sources of radiation having different frequencies (wavelengths) are superimposed upon a semiconductor, mixing action will occur. The resultant intensity will contain the four terms shown below  

Here E and 2 are the amplitudes and cui and coj are the angular frequencies of the two waves. Electron lifetimes in semiconductors are orders of magnitude too large to permit photoexcitation at the sum frequency (of the order, say, of 10 Hz). However, if the difference frequency is less than, say, IGHz, then 

Optical heterodyne detection has become of practical use for systems in which the signal source is a laser, for example, in optical communication systems [2.123] and laser radar [2.124]. Teich [2.125] and Arams et al. [2.126] have reviewed the theoretical basis and experimental results. Keyes and Quist [2.127] include a discussion of optical heterodyne detection in their review of coherent detection. 

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There is a certain imbalance in the level of presentation of the several sections which is due to the nature of the following chapters. The discussion of the photon, thermal, and wave interaction effects is at an introductory level, the purpose of which is to present an overview of the many effects without a detailed analysis of them. Subsequent chapters will treat in depth the important ones. For a similar reason the discussion of noise mechanisms is also at an introductory level. On the other hand, the derivation of the fundamental limits has been reserved to this chapter, since it is common to the later chapters. Thus Section 2.4 is of a much more mathematical nature than the other sections. 

In addition to optical heterodyne detection and parametric effects, other wave interaction effects include those occurring at Josephson junctions and metal-metal oxide-metal contacts. 

In the presence of weak disorder, one should consider an additional contribution to the resistivity due to weak localisation resulting from quantum interference effects and/or that due to Coulomb interaction effects. A single-carrier weak localisation effect is produced by constructive quantum interference between elastically back-scattered partial-carrier-waves, while disorder attenuates the screening between charge carriers, thus increasing their Coulomb interaction. So, both effects are enhanced in the presence of weak disorder, or, in other words, by defect scattering. This was previously discussed for the case of carbons and graphites [7]. 

The curves in Figure B-1 represent primarily the transient nature of blast waves. They do not represent the interaction effects of blast waves and structures, such as multiple reflections and shielding due to the presence of other structures. 

The acceleration of reactions by exposure to microwaves results from material-wave interactions leading to thermal effects (which can easily be estimated by temperature measurement) and specific (not purely thermal) effects. Clearly, a combination of these two contributions can be responsible for the effects observed. 

Microwave effects result from material-wave interactions and, because of the dipolar polarization phenomenon, the greater the polarity of a molecule (such as the solvent) the more pronounced the microwave effect when the rise in temperature [43] is considered. In terms of reactivity and kinetics the specific effect has therefore to be considered according to the reaction mechanism and, particularly, with regard to how the... 

When an electromagnetic wave interacts with resonators, the effect of quantization of all possible stationary stable oscillating amplitudes arises without the requirement of any specifically organized conditions (like the inhomogeneous action of external harmonic force). 

Colloidal potassium has recently been proved as a more active reducer than the metal that has been conventionally powdered by shaking it in hot octane (Luche et al. 1984, Chou and You 1987, Wang et al. 1994). To prepare colloidal potassium, a piece of this metal in dry toluene or xylene under an argon atmosphere is submitted to ultrasonic irradiation at ca. 10°C. A silvery blue color rapidly develops, and in a few minutes the metal disappears. A common cleaning bath (e.g., Sono-clean, 35 kHz) filled with water and crushed ice can be used. A very fine suspension of potassium is thus obtained, which settles very slowly on standing. The same method did not work in THF (Luche et al. 1984). Ultrasonic waves interact with the metal by their cavitational effects. These effects are closely related to the physical constants of the medium, such as vapor pressure, viscosity, and surface tension (Sehgal et al. 1982). All of these factors have to be taken into account when one chooses a metal to be ultrasonically dispersed in a given solvent. 

By considering the extreme case of a crystal completely covered by a layer of foreign atoms, we have already seen in Sec. III,B that, if chemisorption involves the formation of localized electron pair bonds, some interesting interaction effects are to be expected. In this section, we approach the problem from the other extreme by considering just two atoms chemisorbed on a crystal surface. If the localized level formed by the interaction does not lie too far below the normal crystal band (or any surface band), the wave function for the localized level is damped only slowly in the crystal. Therefore, two chemisorbed atoms will be in interaction at distances when the interaction between the isolated atoms would be entirely negligible. To investigate this effect, we take the simplest model which may be expected to yield useful results 11). The crystal is represented by a straight... 

K /Na exchange in distal tubule Dose Adults. 5-10 mg PO daily Peds. 0.625 mg/kg/d X in renal impair Caution [B, ] Contra T K, SCr >1.5 mg/dL, BUN >30 mg/dL, diabetic neuropathy Disp Tabs SE T K HA, dizziness, dehydration, impotence Interactions T Risk of hyperkalemia W/ ACEI, K-sparing diuretics, NSAIDs, K salt substitutes T effects OF Li, digoxin, antihypertensives, amantadine T risk of hypokalemia W/ licorice EMS Monitor ECG for signs of hyperkalemia (peaked T waves) T effects of digoxin OD May cause bradycardia, light-headedness, and syncope symptomatic and supportive... 

The results obtained with the one-center expansion of the molecular spinors in the T1 core in either s p, s p d or s p d f partial waves are collected in Table 4. The first point to notice is the difference between spin-averaged SCF values and RCC-S values the latter include spin-orbit interaction effects. These effects increase X by 9% and decrease M by 21%. The RCC-S function can be written as a single determinant, and results may therefore be compared with DF values, even though the RCC-S function is not variational. The GRECP/RCC-S values of M indeed differ only by 1-3% from the corresponding DF values [89, 127] (see Table 4). 

For a strong primary shock wave, the reflected rarefaction wave propagates into water that has already been set in motion. Consequently, the rarefaction wave arrives earlier than predicted from the acoustic approximation, which ignores the particle velocity. Thus the pressure cutoff is not instantaneous. This effect typically gives a pulse shape shown by the solid line for Point A of Fig 33. The shallower the point at which pressure measurements are made, the sooner the primary shock pulse is truncated and the shorter its duration (see Fig 33, Point B). At shallow enough locations, the rarefaction wave interacts with the shock front and reduces the peak pressure (see Fig 33, Points C and D). The region in which the peak pressure is reduced is known as the anomalous region ... 

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