Popov Mikhail, Khorobrykh Fedor, Klimin Sergei, Churkin Valentin, Ovsyannikov Danila, Kvashnin Alexander
Technological Institute for Superhard and Novel Carbon Materials, 7a Tsentralnaya, 108840 Troitsk, Moscow, Russia.
Phystech School of Electronics, Photonics and Molecular Physics, Moscow Institute of Physics and Technology Institutskiy per. 9, 141700 Dolgoprudny, Moscow, Russia.
Nanomaterials (Basel). 2023 Feb 10;13(4):696. doi: 10.3390/nano13040696.
We observed resonance effects in the Raman scattering of nanodiamonds with an average size of 2-5 nm excited at a wavelength of 1064 nm (1.16 eV). The resonant Raman spectrum of the 2-5 nm nanodiamonds consists of bands at wavelengths of 1325 and 1600 cm, a band at 1100-1250 cm, and a plateau in the range from 1420 to 1630 cm. When excited away from the resonance (at a wavelength of 405 nm, 3.1 eV), the Raman spectrum consists of only three bands at 1325, 1500, and 1600 cm. It is important to note that the additional lines (1500 and 1600 cm) belong to the sp-hybridized carbon bonds. The phonon density of states for the nanodiamonds (~1 nm) was calculated using moment tensor potentials (MTP), a class of machine-learning interatomic potentials. The presence of these modes in agreement with the lattice dynamics indicates the existence of bonds with force constants higher than in single-crystal diamonds. The observed resonant phenomena of the Raman scattering and the increase in the bulk modulus are explained by the presence of Tamm states with an energy of electronic transitions of approximately 1 eV, previously observed on the surface of single-crystal diamonds.
我们在平均尺寸为2 - 5纳米的纳米金刚石的拉曼散射中观察到共振效应，这些纳米金刚石在波长为1064纳米（1.16电子伏特）的光激发下产生散射。2 - 5纳米纳米金刚石的共振拉曼光谱由波长为1325和1600厘米⁻¹处的谱带、1100 - 1250厘米⁻¹处的谱带以及1420至1630厘米⁻¹范围内的一个平台组成。当在非共振波长（405纳米，3.1电子伏特）激发时，拉曼光谱仅由1325、1500和1600厘米⁻¹处的三个谱带组成。需要注意的是，额外的谱线（1500和1600厘米⁻¹）属于sp杂化碳键。使用矩张量势（MTP，一类机器学习原子间势）计算了纳米金刚石（~1纳米）的声子态密度。这些模式与晶格动力学一致的存在表明存在力常数高于单晶金刚石的键。拉曼散射中观察到的共振现象以及体积模量的增加是由能量约为1电子伏特的电子跃迁的塔姆态的存在来解释的，此前在单晶金刚石表面已观察到这种塔姆态。
