Carbon-Based Nanomaterials for Plasmonic Sensors: A Review <s> Graphene <s> We characterize the influence of graphene nanoribbon plasmon excitation on the vibrational spectra of surface-absorbed polymers. As the detuning between the graphene plasmon frequency and a vibrational frequency of the polymer decreases, the vibrational peak intensity first increases and is then transformed into a region of narrow optical transparency as the frequencies overlap. Examples of this are provided by the carbonyl vibration in thin films of poly(methyl methacrylate) and polyvinylpyrrolidone. The signal depth of the plasmon-induced transparency is found to be 5 times larger than that of light attenuated by the carbonyl vibration alone. The plasmon-vibrational mode coupling and the resulting fields are analyzed using both a phenomenological model of electromagnetically coupled oscillators and finite-difference time-domain simulations. It is shown that this coupling and the resulting absorption enhancement can be understood in terms of near-field electromagnetic interactions. <s> BIB001 </s> Carbon-Based Nanomaterials for Plasmonic Sensors: A Review <s> Graphene <s> Graphene plasmons can couple with vibrations in both extended and local systems, for example, phonons in polar crystals and molecular vibrations in polymers. These interactions are characterized by plasmon-induced transparency features within the plasmon infrared absorption profile. Detection enhancement made possible by graphene-based plasmon-induced transparency has been demonstrated in both polymer and protein films and has shown to offer superior detection capabilities compared to conventional metal dipole plasmonic sensors. Here, we demonstrate the detection of molecular vibrations in minute, residual molecular quantities of solid- and gas-phase molecules down to 50 zeptomol/μm2 using graphene plasmonic sensing platforms. Plasmon-induced transparency enhancement is shown to be sensitive to both the specific molecular coordination of the measured vibrations and to the distribution of modes within the measured vibrational bands. This work could lead to the development of functionalization-free, chemica... <s> BIB002
Recently, a graphene-based plasmonic refractive index sensor has been theoretically investigated. The sensor works in the mid-infrared region at room temperature and graphene plasmon frequency shifts for a small change in the refractive index around the graphene sheet have been observed. The resonance wavelength was found to increase with an increasing refractive index of the medium around the graphene BIB001 . The sensor possesses a sensitivity of 2.5 µm/RIU, which means the resonance wavelength shifts by 2.5 µm for every unit change in refractive index. Here, RIU means refractive index unit. The figure of merit (FOM) of the sensor was reported to be around 10.7. Similar to this, various graphene-based plasmonic sensors have been reported in the literature for different applications BIB002 BIB001 .