9-扶手椅石墨烯纳米带阵列中的表面依赖声子动力学
Surface-Dependent Phonon Dynamics in 9-Armchair Graphene Nanoribbon Arrays
- Swiss Federal Laboratories for Materials Science and Technology (Empa)（瑞士联邦材料科技研究所）
- University of Basel（巴塞尔大学）
- Swiss Nanoscience Institute, University of Basel（巴塞尔大学瑞士纳米科学研究所）
- University of Zürich（苏黎世大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究通过变温拉曼光谱研究9-AGNRs阵列，发现D/G模红移主要由衬底-纳米带热膨胀失配主导，而非Klemens非谐项，且密集Au阵列存在异常线宽最小值。
AI中文摘要：
我们利用变温拉曼光谱研究了五种原子级精确的9-扶手椅石墨烯纳米带（9-AGNRs）构型，这些构型在衬底、排列方式和覆盖率上有所不同。在70至300 K的温度范围内进行测量，并通过全窗口洛伦兹拟合获得了径向呼吸类模式（RBLM）、限域激活的D模和G模的位置与线宽。D模和G模在加热过程中以依赖于构型的速率发生软化。对于同一未排列的高覆盖率薄膜，在无聚合物转移前后，测得的D模和G模红移速率在拉曼优化衬底上分别比在Au上小4.7倍和5.6倍。我们将频率位移建模为来自衬底-纳米带热膨胀失配的热弹性贡献加上Klemens型非谐项。在80至290 K之间，该模型给出的D模和G模红移范围为0.305至6.322 cm⁻¹，而以零K为参考的Klemens型贡献保持在0.050 cm⁻¹以下。在所采用的假设下，热膨胀失配因此主导了这些位移。模拟的RBLM变化保持在1 cm⁻¹以下，无法稳健地将其分离为两种贡献。此外，密集排列的Au阵列在D模和G模线宽中表现出中间温度最小值，这与传统的单调非谐展宽不一致，表明存在额外的温度依赖展宽或线形贡献。
英文摘要：
Atomically precise graphene nanoribbons (GNRs) have electronic properties tunable through their width and edge structure, making them promising building blocks for nanoscale electronics and optoelectronics. Their integration into devices also requires understanding how the supporting surface and neighbouring ribbons affect their vibrations. Here, we use temperature-dependent Raman spectroscopy to compare five configurations of 9-armchair GNR arrays differing in substrate, alignment and coverage. Transferring the same unaligned film from Au to a Raman-optimised Al$_2$O$_3$-coated support reduces the measured $D$- and $G$-mode redshift rates by about 80\%. This reduction is consistent with a substantial thermoelastic contribution. The fitted strain and anharmonic contributions depend on the assumed thermal expansion and strain transfer. Compared with the low-coverage array, the dense aligned Au array has higher extrapolated reference frequencies ($ω_0$). On first heating, its $G$-mode linewidth decreases and then increases, forming an unusual intermediate-temperature minimum. The $D$-mode linewidth shows a similar, less pronounced variation. These findings establish substrate choice and array arrangement as routes to engineer nanoribbon vibrations, extending control beyond the atomic structure defined during synthesis.
