Microwave resonators

Figure 3. Different geometries for microwave conductivity measurements, (a) Sample (black square) at end of microwave guide, (b) sample in microwave resonator, and (c) sample above dielectric microwave spiral. The electrical field E of the microwave is shown schematically.

Figure 40. PMC peak measured with a ZnO single-crystal electrode in a microwave resonator near the onset of the anodic photocurrent.5...

From a study of the microwave spectrum of 2-methylselenophene, the second-order Stark effect in the ground state was determined.11 The technique used was double radiofrequency-microwave resonance. For the identification by the double resonance method transitions of chiefly the A-state were chosen. From these observations the components of the dipole moment of 2-methylselenophene and the total dipole moment were determined. 

Functionalized Nanomaterials to Sense Toxins/Pollutant Gases Using Perturbed Microwave Resonant Cavities... 

Keywords Carbon nanotubes, chemical and biological sensors, microwave resonance, resonant cavities... 

A cylindrical microwave resonant cavity can be considered to be N LCR circuits arranged in parallel, where N tends to infinity. The cavity is constructed by A/4 sections of such circuits as described in the Air Force manual Radar Circuit Analysis (1950). 

Anand A (2007) studying interactions of gas molecules with nanomaterials loaded in a microwave resonant cavity, Ph.D. dissertation, University of North Texas, Texas, USA. 

C. Buschmilller, W. Wiedey, C. Doscher, J. Dressier and J. Breitkreutz, In-line monitoring of granule moisture in fluidized-bed dryers using microwave resonance technology, Eur. J. Pharm. Biopharm., 69, 380-387 (2008). 

Buschmuller et have demonstrated that microwave resonance can be used effectively as means to monitor the moisture levels in a fluidized-bed dryer during the granulation process. The penetration depth of microwave resonance may be limited to a few microns, and hence this technique may not have any real advantages over NIR which has also been used for monitoring moisture in dryers, and has the advantage of providing chemical information such as solvent levels in addition to water, and other important properties such as polymorphic form, and particle size. 

TM9-1910 (1955), 41-2 (Rate of deton) 55) E.F. Pound M.A. Cook, "The Measurement of Detonation Velocity by Microwave Resonator Techniques , Univ of Utah, TechRept 44(1955), Contract N7-onr-45107 56) H.T, Knight ... 

M.A.Cook, "The Measurement of Detonation Velocity by Microwave Resonator Techniques ,... 

Why microwave resonance techniques are so attractive for the spectroscopy of Rydberg states becomes clear when we estimate how much microwave power is required to drive the transitions. To drive the electric dipole ml— ni transition A... 

Measuring the M intervals by microwave resonance techniques generally yields the fine structure intervals as well. However, A = 0 transitions between the fine structure levels can also be examined by several other techniques. The first of these is rf resonance. Since the transition involves no change in Z it is not an electric dipole transition but rather a magnetic dipole transition, and a straightforward approach is magnetic resonance, which has been used by Farley and Gupta36 to measure the 6f and 7f fine structure intervals in Rb. Their approach is... 

Three different methods have been used to make microwave resonance measurements of intervals between alkaline earth Rydberg states. In all of these measurements state selective laser excitation of alkaline earth atoms in a beam was combined with one of three forms of state selective ionization of the final states. 

Since more than one rf interval has been measured, it is, in principle, possible to determine both the quadrupole and dipole polarizabilities from the microwave resonance data alone. The procedure is identical to that used earlier for alkali atoms,15 except that the factors kd and kq must be introduced. If we define... 

Most of the high precision spectroscopy of He Rydberg states has been done by microwave resonance, which is probably the best way of obtaining the zero field energies. Wing et a/.8-12 used a 30-1000pA/cm2 electron beam to bombard He gas at 10-5-10-2 Torr. As electron bombardment favors the production of low states, it is possible to detect A transitions driven by microwaves. The microwave power was square wave modulated at 40 Hz, and the optical emission from a specific Rydberg state was monitored. When microwave transitions occurred to or... 

The analysis system consisted of a Shimsdzu QC-6A gas chromatograph, a chemically deactivated four-way valve for solvent ventilation, a heated transfer tube interface, a Beenakker-type TM0i0 microwave resonance cavity, and an Ebert-type monochromator (0.5m focal length). 

Microwave resonant devices these operate between 0.5 and 50 GHz and require stabilities of better than +0.05% over the operational temperature range with dissipation factors better than 2 x 10 4. 

Fig. 5. 33 Fields in a microwave resonance dielectric in the simplest standing wave mode (a) magnetic field (b) electric field (c) variation in Ev and Ez with r at z — 0, with reference to cylindrical coordinates (the z axis is perpendicular to the plane of the disc and the origin is at the disc centre).

The experimental uncertainty of 0.06 MHz for the 2 3S state corresponds to an accuracy of 15 parts per million (ppm) in the total QED shift. This considerably exceeds the accuracy of the best microwave resonance measurement of the Lamb shift in the He+ hydrogenic ion ( 86 ppm) [57], and it matches the accuracy of the recent anisotropy measurement by van Wijngaarden et al. [58],... 

Fig. 12. Expected timespectra with laser spikes (left) and laser as well as microwave resonance curves (right)...

A method to observe microwave resonances in antiprotonic helium has been proposed and is being prepared for the coming antiproton decelerator (AD) ring at CERN [36]. It is called 2-laser-microwave triple resonance method, which has the following steps. 

Fig. 4. Two-laser microwave triple resonance experiment explained at the example of the already observed (n, L) = (37,35) — (38,34) transition. Left Simulated delayed annihilation time spectra of the laser/microwave triple resonance method. Right Simulated laser and microwave resonance profiles...

We have, we hope, provided enough detail about the Zeeman effect to show how almost every microwave resonance could be assigned, so far as the J values were concerned. A final remark should be made concerning the parity labels. These depend upon the identification of a J = 1 /2 <- 1/2 transition, and the measured g-factors for the two J = 1/2 levels which identify their e//, and hence total parities. The parities of all other levels then follow because all transitions are electric-dipole allowed, between states of opposite parity. As we have mentioned earlier, the combination of numerical relationships between the resonance frequencies, double resonance studies, and Zeeman effect measurements enabled the pattern of levels lying within 8 cm 1 of the dissociation limit to be established. The highest level, J = 7/2 (—parity), in figure 10.74, was thought to lie within 20 MHz (<0.001 cm-1) of the dissociation limit. 

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