Alternating fields circularly polarized

Plane or linear polarization of radiation, given in Eqs. (7.4) and (7.5), is not the only possibility. One alternative is circular polarization in the form of left-circularly polarized and right-circularly polarized waves whose electric-field vectors are given as... 

Radiation which induces NMR transitions is usually produced by radiofrequency (RF) coils wound around the sample. These are energized by alternating currents approximately matching the Larmor frequency. The coils are arranged so that the magnetic field of the radiation Bi is perpendicular to the static field Bq. In contrast to other types of spectroscopy, the electric field of the radiation plays no role here. The simplest case is a circularly polarized RF field, such that, in the laboratory frame,... 

Quadrupole mass analyzers consist of four parallel circular or hyperbolic rods (Figure 1.17). Each pair of opposite rods are electrically connected and supplied voltages of the same magnitude but different polarity. The voltage applied to each pair consists of a direct current (DC), U, and a radiofrequency (rf) component, Vcosot. Typical values are several himdred volts for U, several ttiousand volts for V, and megahertz for m. Since the total potential of each rod is -i-(U + V cos tot) or -(U + Vcostot), the rf field periodically alternates the rods polarity. ... 

Figure 2 Intensity versus magnetic field traces for the Frederik s distortion of MBBA as monitored by (A) alternate senses of circularly polarized light as in Figure 1 and (B) the conventional method using linearly polarized light at a fixed angle with respect to the analyzer. Arrows indicate the onset of the distortion. (The intensity scales are identical for both traces and the sample was undisturbed between the two measurements).

There are a number of methods to overcome this loss of atoms by optical pumping. For example, there could be two laser beams tuned for excitation out of each hfs state, the laser spectrum could be sufficiently broad to excite both hfs states, there could be an rf or microwave field that would induce hfs transitions to return atoms to the appropriate hfs state, or optical pumping could be inhibited by careful choice of experimental conditions. For a variety of carefully considered technical reasons, we employ the last of these alternatives. We use circularly polarized light and the axis provided by the magnetic tuning field to allow only excitations to a particular sublevel of the atomic excited state. The only strongly allowed decay process returns the atom to the original state. 

The paper by Hunyh et al. (1978) on the Mossbauer effect of low-spin Fe " in cytochrome c from Rhodospirillum rubrum highlights the value of analyses that search out fundamental properties of the system. While measurements of the sign of the product QxQyQz can be made using ESR with circularly polarized radiation (see Section 2.2.3), the measurements and analysis by Hunyh et al (1978) provides a valuable alternative. They noted that in Mossbauer spectroscopy under weak magnetic field conditions. 

The two circularly-polarized waves form an alternative set of independent field polarizations which is especially useful in many problems concerning the interaction of light with atoms subjected to external magnetic fields. If we define the basis of spherical orthogonal unit vectors by the relations... 

Cyclotrons are also used as heavy-ion sources. In a cyclotron, ions are confined to circular or spiral orbits by a dipolar magnetic field. The ions are accelerated by an alternating electric field projected by a series of plates above and below the orbital plane of the ions. In the simplest case, there are two sets of half-circular plates called "dees , which alternate in polarity to accelerate the ions. 

---