Raman phonon scattering

Keywords layered cobaltites, Co3+ ion spin state, Raman light scattering, phonon... 

To evaluate the crystallinity of the films, Raman spectroscopy is used. A typical Raman spectrum is presented in Fig. 4. Of the crystalline diamond, a narrow peak at a frequency of 1332 cur1 is characteristic, which is caused by the first-order phonon scattering by the crystal lattice. The non-diamond carbon is represented in the spectrum by two diffuse bands at ca. 1350 and 1550 cm-1. When comparing the peaks height, one should keep in mind that the Raman signal is 50 times more sensitive to the non-diamond carbon than to the crystalline diamond [20], In the high-quality diamond films used as electrodes, the non-diamond carbon component rarely exceeds 1%. Raman spectroscopy data have been corroborated by the independent impedance spectroscopy measurements (see below). According to [21], the inner layer of a diamond film is enriched with the admixture of non-diamond carbon as compared to its outer layer. 

Fig. 3.7. Polarized micro-Raman spectra of a (0001) ZnO bulk sample (a) and a (0001) ZnO thin film (d 1,970 nm) on (0001) sapphire (b). The vertical dotted and dashed lines mark ZnO and sapphire (S) phonon modes, respectively. MP denotes modes due to multi-phonon scattering processes in ZnO. Excitation with Ar+-laser line A = 514.5 nm and laser power P < 40 mW. Reprinted with permission from [38]...

The fundamental role of the dynamic electron-phonon coupling in the Jahn-Teller crystals was clearly demonstrated by the Raman light scattering experiments [18],... 

This is an appropriate place to mention that besides the low-frequency bands associated with some adsorbed species, there are several other Raman features which are related to the (rough) metal itself. Macomber and Furtak have reported weak and broad features at 160 and 110 cm which they associated with silver bulk phonon scattering. These bands, and, in addition, one at 73 cm have been seen earlier by Pockrand and Otto, in an UHV system. 

Fig. 3. Electronic Raman scattering from the /-multiplet levels of Smj Yj.Se at 80 K for sl.O for = 0.05, the La-substituted Sm jjLao ojSe is shown. The scattering configuration is the same as in fig. 2. The hatched area indicates the electronic scattering from the J-0-> 1 excitation. Phonon scattering is seen below 200 cm ...

Fig. 4. Polarized Raman spectra of Sm, Y S (x = 0, 0.10, 0.25) and of SmogjGdojjS in the black and pressure-transformed (p>4kbar) gold phase at 80 K. The scattering configuration is the same as in fig. 2. Dashed line below 300 cm , phonon scattering hatched area, electronic scattering form the / = 0— 1 excitation.

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