Microwave saturation properties

The various maceral types exhibit distinctly different microwave saturation properties. 

The separation of signals from different species by means of different microwave saturation has been applied in work on irradiated spices [76]. A typical spectrum may contain contributions from transition metal ions, particularly, Mn, and a radiation organic radical, sometimes overlapped with another naturally occurring free radical spectrum. It was recommended that the microwave saturation properties should be considered in future protocols to survey the radiation history of soft foodstuffs. 

Procedures to obtain relaxation times T and T2 from microwave (CW) saturation curves of the type shown in Fig. 2.28 were developed many years ago [53-56], The method has recently been applied to characterize saturation properties of samples... 

Sengwa, R.J., Soni, A., 2006. Low-frequency dielectric dispersion and microwave dielectric properties of dry and water-saturated limestraies of the Jodhpur region. Geophysics 71 (5), 269-277. 

The saturation behavior of a spectrum - the variation of integrated intensity with microwave power - is related to the spin-lattice relaxation time, a measure of the rate of energy transfer between the electron spin and its surroundings. Saturation often depends on the same structural and dynamic properties as line widths. 

It should be pointed out that once the zf origin of the different bands is determined (in particular the true and false origins of the spectrum), a complete description could be given for the spin-orbit perturbations that give the lowest triplet state its radiative properties. A very extensive work was conducted by Tinti and El-Sayed (39) in which different perturbations—e.g., heating, applying a magnetic field, as well as saturation of the zf transitions with microwave radiation-were used to determine the property of the individual zf levels. The effect of these perturbations not only on the phosphorescence spectrum but also on the observed decays and polarizations has been examined. Limits on the importance of the different spin-orbit interactions are obtained. This spectroscopic work represents the type of experiments that can be done and the kind of information that can be obtained from PMDR and other methods. 

Microwave EDLs. In the microwave EDLs the pressure of the inert gas must be about 0.13 kPa when the temperature is 480 to 680 K. The material placed in the tube is pure metal or its chloride or iodide. The addition of 1 to 2 mg of mercury or saturation of the tube by mercury vapour prevents the adsorption of the metal, and hence improves the radiation properties of the lamp and adds to its lifetime. The intensity of the radiation is controlled by the temperature of the lamp, because the vaporization of metal is mainly thermally induced. Therefore, the microwave EDL must be temperature regulated by a thermostat in order to make the intensity stable enough for analytical use. 

---