Theoretical and experimental vibrational spectra of ReSe₂ nanocrystals, synthesized by self‐limited chemical vapor deposition (CVD), are reported. Scanning electron microscopy reveals that the nanocrystals have the shape of polygon nanoplates (NPs), 20 nm thick and about 100–300 nm wide. X‐ray diffraction studies determined their triclinic structure (space group, P‐1 [no. 2]). The wavenumbers of the Raman‐ and infrared (IR)‐active phonon modes were calculated using the density functional perturbation theory (DFPT), along with the dispersion curves and phonon density of states. The set of theoretical phonon wavenumbers is found to correlate well with the experimental Raman and IR spectra. We established that, unlike ReS₂, ReSe₂ does not exhibit a “phonon gap.” Several “extra” bands in the experimental Raman spectrum of ReSe₂ are argued to be defect‐induced contributions of phonons from F and Q critical points of the Brillouin zone. In addition, the effect of Fermi resonance is observed in the Raman spectrum of the ReSe₂ NPs, which manifests itself in an increase of the intensity of second‐order bands due to their interaction with first‐order phonons.

中文翻译：

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ReSe2纳米板的结构和振动光谱

报告了通过自限化学气相沉积（CVD）合成的ReSe ₂纳米晶体的理论和实验振动光谱。扫描电子显微镜显示，纳米晶体具有多边形纳米板（NP）的形状，厚20 nm，宽约100-300 nm。X射线衍射研究确定了它们的三斜结构（空间群，P-1 [编号2]）。拉曼和红外（IR）激活声子模式的波数是使用密度泛函微扰理论（DFPT）以及色散曲线和声子密度来计算的。发现该组理论声子波数与实验拉曼光谱和红外光谱具有很好的相关性。我们确定，与ReS ₂不同，ReSe ₂没有“声子间隙”。ReSe ₂实验拉曼光谱中的几个“额外”谱带被认为是布里渊区F和Q临界点声子的缺陷诱导贡献。此外，在ReSe ₂ NPs的拉曼光谱中观察到了费米共振的影响，由于其与一阶声子的相互作用，其自身表现为二阶能带强度的增加。