Raman scattering under extreme conditions<xref rid="cpb_27_7_077801_fn1" ref-type="fn">*</xref><fn id="cpb_27_7_077801_fn1"> <label>*</label><p>Project supported by the Ministry of Science and Technology of China (Grant Nos. 2016YFA0300504 and 2017YFA0302904) and the National Natural Science Foundation of China (Grant Nos. 11474357, 11774419, 11604383, and 11704401). Y. Y. was supported by the Scientific Equipment Development Project of Chinese Academy of Sciences (Grant No. YJKYYQ20170027).</p></fn>

Raman scattering under extreme conditions* *

Project supported by the Ministry of Science and Technology of China (Grant Nos. 2016YFA0300504 and 2017YFA0302904) and the National Natural Science Foundation of China (Grant Nos. 11474357, 11774419, 11604383, and 11704401). Y. Y. was supported by the Scientific Equipment Development Project of Chinese Academy of Sciences (Grant No. YJKYYQ20170027).

Jin Feng¹, Yang Yang², Zhang An-Min¹, Ji Jian-Ting^{1, 2}, Zhang Qing-Ming^{1, 2, 3, †}

(color online) (a) Temperature-dependent Raman spectra of TiSe₂. The inset shows the displacement pattern associated with the CDW distortion, for Ti atoms (solid circles), Se atoms above Ti layer (open circles), and Se atoms below Ti layer (shaded circles). Pressure dependence of Raman spectra at T = 3.5 K for E_g CDW mode (b), A_1g CDW and E_g optical phonon modes (c), and A_1g optical phonon mode (d). The inset of panel (d) shows the pressure dependence of A_1g (red circles) and A_1g-CDW (blue squares) phonon linewidths (FWHM). Pressure dependence of peak energies (circles) and normalized intensities, I(P)/I(P = 0) (squares) at T = 3.5 K for A_1g (e), E_g (f), A_1g-CDW (g), and E_g-CDW (h) modes. The hatched lines denote rough boundaries between crystalline CDW, soft CDW, and disordered CDW regimes. Reprinted with permission from Ref. [13], copyright 2003 by the American Physical Society.