Kamali K, Irshad K A, Sundaramoorthy Muthukumaran, Joseph Boby, Das Dipti P
CSIR-Institute of Minerals and Materials Technology, Odisha, India.
Elettra - Sincrotrone Trieste S.C. p. A., S.S. 14, Km 163.5 in Area Science Park, Basovizza 34149, Italy.
Nanoscale. 2025 Jun 19;17(24):14874-14886. doi: 10.1039/d5nr00831j.
The high-pressure (HP) effect on surface-enhanced Raman spectroscopy (SERS) is a new horizon due to the importance of pressure, an external stimulus that can tune the lattice and electronic band structure of the SERS substrate and the analyte molecule. Here, we have used nano-ZIF-67 as the pressure induced (PI)-SERS substrate and R6G molecules as the analyte to explore the SERS effect in both the compression and decompression cycles. Our results demonstrate SERS signal enhancement at 0.12, 0.38 and 1.12 GPa. The initial SERS enhancement at 0.12 GPa is found to be due to inter-band transition resonance. A HP synchrotron diffraction study on the ZIF-67/R6G system illustrated an initial expansion of the ZIF-67-unit cell due to the infiltration of R6G molecules inside the pores and a structural phase transition around 0.38 GPa followed by an irreversible amorphization around 3 GPa. A significant SERS enhancement is also observed when decompressed to ambient pressure after a maximum pressure of 6.42 GPa. Although the crystal lattice seems to collapse irreversibly with HP, our Raman investigations indicated the recovery of the phonon modes upon pressure release. This observation indicates an important role of the local atomic arrangements in the SERS enhancement upon the pressure release.
由于压力这一外部刺激的重要性，高压（HP）对表面增强拉曼光谱（SERS）的影响是一个新的研究领域，压力能够调节SERS基底和分析物分子的晶格以及电子能带结构。在此，我们使用纳米ZIF-67作为压力诱导（PI）-SERS基底，以R6G分子作为分析物，来探究在压缩和减压循环中的SERS效应。我们的结果表明在0.12、0.38和1.12 GPa时SERS信号增强。发现在0.12 GPa时最初的SERS增强是由于带间跃迁共振。对ZIF-67/R6G体系进行的高压同步辐射衍射研究表明，由于R6G分子渗入孔内，ZIF-67晶胞最初发生膨胀，在0.38 GPa左右发生结构相变，随后在3 GPa左右发生不可逆的非晶化。在6.42 GPa的最大压力后减压至常压时，也观察到显著的SERS增强。尽管晶格在高压下似乎不可逆地坍塌，但我们的拉曼研究表明在压力释放时声子模式得以恢复。这一观察结果表明局部原子排列在压力释放时的SERS增强中起着重要作用。
