Plasma edge/frequency

TTF type. The optical anisotropy of such two-dimensional conductors and their electron parameters may also be deduced from reflectance studies. As an example, from the (TMTSF)2X family we present the polarized reflectance of (TMTSF)2PF6 at three temperatures (Fig. 7). It is evident that optical anisotropy decreases at low temperature, and a reasonably well-defined plasma edge appears in the b direction at 25 K. The transverse reflectance edge appears at the frequency about 10 times lower than that of the stacking axis edge (tb< = 22 meV, about 10 times smaller than ta) [46]. Drude parameters for typical (TMTSF)2X salt are eq = 3.5, 1500 cm-1 < cop < 2000 cm-1, 250 cm-1 < y < 500 cm-1, and tb = 0.02 eV. 

The metallic component r(e ] c displays the expected plasma edge with a minimum at 9200 cm and high, metallic reflectance in the infrared. Apart from a shift of plasma frequency, no significant difference is found between TTF-TCNQ and HMTSF-TCNQ in the reflectance data. For example, a small dip in the reflectance around 1600 cm is seen in both materials. 

Finally, in case n, fi are small, optical measurements can be replaced by measurements of e (measure of capacity in which the material is placed). In semiconductors, optics is the convenient tool to measure rwp since it is located at frequencies that are of easy access to optical devices. In metals where the plasma frequency is in the near UV, it may be more convenient to if the plasma edge is the near UV, it may be more convenient to send an electron beam on the metal, at normal incidence, and look at the spectral energy of the reflected beam. Normal incidence is needed to excite the plasma wave at the plasma frequency, because it is a longitudinal wave. Like any wave, the electron motion must be quantified, which means that the incident beam can create quanta of vibrations of the plasma, quasiparticles named plasmons, of energy hwp. In the process, some of the reflected electrons have lost the kinetic energy hcop, which can be detected by analysis of the energy profile of the reflected beam. 

TMS deposition rate profiles in DC, 40-kHz, and 13.56-MHz discharges are shown for electrode in Figure 13.2. It can be seen that, regardless of the frequency of electrical power source used, a uniform deposition of TMS polymers was observed in the three plasma processes, although an appreciable edge effect occurred in the DC and a less pronounced effect occurred in the 40-kHz discharge when the substrate was used as the cathode or powered electrode. The uniform distribution of deposition rates justifies the use of single measurement at the center of the electrode to represent the characteristic deposition rate of a system. 

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