Lombardi John R
Department of Chemistry and Biochemistry, The City College of New York, New York, NY 10031, USA.
Nanomaterials (Basel). 2022 Aug 9;12(16):2737. doi: 10.3390/nano12162737.
Drawing on a theoretical expression previously derived for general semiconductor substrates, we examine the surface-enhancement of the Raman signal (SERS) when the substrate is chosen to be monolayer graphene. The underlying theory involves vibronic coupling, originally proposed by Herzberg and Teller. Vibronic coupling of the allowed molecular transitions with the charge-transfer transitions between the molecule and the substrate has been shown to be responsible for the SERS enhancement in semiconductor substrates. We then examine such an expression for the Raman enhancement in monolayer graphene, which is dependent on the square of the derivative of the density of states of the graphene. On integration, we find that the discontinuity of the density-of-states function leads to a singularity in the SERS intensity. Knowledge of the location of this resonance allows us to maximize the Raman intensity by careful alignment of the doping level of the graphene substrate with the charge-transfer transition.
基于先前为一般半导体衬底推导的理论表达式，我们研究了当衬底选为单层石墨烯时拉曼信号的表面增强（SERS）。其基础理论涉及最初由赫兹伯格和泰勒提出的振动-电子耦合。已表明允许的分子跃迁与分子和衬底之间的电荷转移跃迁的振动-电子耦合是半导体衬底中SERS增强的原因。然后我们研究单层石墨烯中拉曼增强的这种表达式，它取决于石墨烯态密度导数的平方。通过积分，我们发现态密度函数的不连续性导致SERS强度出现奇点。了解这种共振的位置使我们能够通过仔细调整石墨烯衬底的掺杂水平与电荷转移跃迁来最大化拉曼强度。
