Surface-Enhanced Raman Scattering Stimulated by Strong Metal–Molecule Interactions in a C₆₀ Single-Molecule Junction

Abstract

Specifying the geometric and electronic structures of a metal–molecule interface at the single-molecule level is crucial for the improvement of organic electronics. A single-molecule junction (SMJ) can be used to investigate interfaces because it can be regarded as an elementary unit of the interface structure. Although considerable efforts have been made to this end, the detection of structural changes in SMJs associated with metal–molecule interactions remains challenging. In this study, we detected the surface-enhanced Raman scattering (SERS) signal originating from the metal–molecule interaction change induced by a local structural change in a C60 SMJ. This junction has attracted wide attention owing to its unique electronic and vibronic properties. We fabricated a C60 SMJ using a lithographically fabricated Au electrode and measured the SERS spectra along with the current–voltage (I–V) response. By continuous measurement of SERS for the C60 SMJ, we obtained SERS spectra dependent on the local structural change. The analysis of the I–V response revealed that the vibration energy shift originates from the change in the local structure for different Au–C60 interactions. Based on the discrimination of the states in accordance with the Au–C60 interaction, we found that the probability of SERS for geometry with a large Au–C60 interaction was enhanced.

Fullerene Nanostructure-Coated Channels Activated by Electron Beam Lithography for Resistance Switching

“…Resistance in the low voltage regime (Figure c) was drastically lowered from that exhibited by the simple shape long wire. It is possible that the wider connection of the EBL channel to the AuPd contact generates a larger current into the channel from various types of C 60 –Au bonding . These modifications were reflected in the NDR operation (Figure d), where the NDR voltage was lowered and the NDR peak current was increased, which suggests that the current flow was concentrated in the narrowed channel.…”

Electromechanical Switching of a C60 Chain in a Nanogap

“…Nanogap fabrication could realize a single or small number of fullerene channels for the observation of the electrical behavior of individual fullerenes . Although these devices exhibit unique intrinsic properties of a fullerene, chemical reactions related to polymerization and depolymerization between adjacent fullerenes are yet to be revealed.…”

Graphene-Covered Silver Nanoisland Array Coupling with Hyperbolic Metamaterials for SERS Sensing

“…Surface-enhanced Raman spectroscopy (SERS) has been extensively applied in chemistry, − biosensors, , food detection, and environmental monitoring for its ability to identify molecules from their vibrational spectra at significantly low concentrations. In general, the activity of SERS is dependent on two mechanisms.…”