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) Structure of A7 semimetals and photo-induced reversed Peierls transition. Photo-excitation reduces the population of valence bands, hence reducing the electronic energy gain of Peierls distortion, and driving the system toward the undistorted phase. (b) A_1g phonon frequency in Sb measured at 15 ps after photo-excitation. The agreement between the model and the data indicates that electronic heat diffusion plays a minor role in the relaxation processes. (c) The symmetry reduction due to the photo-induced phase transition leads to the emergence of an additional phonon mode on the low-energy side of A_g mode for excitation densities larger than 5 mJ/cm². Reprinted with permission from Ref. [53], copyright 2009 by the American Physical Society.