Theoretical investigation of a plasmonic substrate with multi-resonance for surface enhanced hyper-Raman scattering

Abstract

Because of the unique selection rule, hyper-Raman scattering (HRS) can provide spectral information that linear Raman and infrared spectroscopy cannot obtain. However, the weak signal is the key bottleneck that restricts the application of HRS technique in study of the molecular structure, surface or interface behavior. Here, we theoretically design and investigate a kind of plasmonic substrate consisting of Ag nanorices for enhancing the HRS signal based on the electromagnetic enhancement mechanism. The Ag nanorice can excite multiple resonances at optical and near-infrared frequencies. By properly designing the structure parameters of Ag nanorice, multi- plasmon resonances with large electromagnetic field enhancements can be excited, when the “hot spots” locate on the same spatial positions and the resonance wavelengths match with the pump and the second-order Stokes beams, respectively. Assisted by the field enhancements resulting from the first- and second-longitudinal plasmon resonance of Ag nanorice, the enhancement factor of surface enhanced hyper-Raman scattering can reach as high as 5.08 × 109, meaning 9 orders of magnitude enhancement over the conventional HRS without the plasmonic substrate.

Plasmon coupling nanorice trimer for ultrahigh enhancement of hyper-Raman scattering

“…In recent years, the development of active plasmonic substrates has provided huge boost for the study of surface-enhanced spectroscopy. HRS has also been extensively studied in the single molecule detection 20 and the design of active substrates 35 . We know that it is a second-order nonlinear optical detection 42 .…”

“…Recently, we have designed and researched a kind of SEHRS substrate in theory, which was consisted of Ag nanorice 35 . To achieve a significant amplification of the HRS signal, the two plasmon resonance modes in this nanostructure were matched with the excitation and the second-order Stokes lights, respectively.…”

Raman Excitation of Hydrogen Molecules to v = 1 State

“…Non-linear Raman processes is one of such spectroscopic technique which has been feasible with employment of lasers. Spontaneous Raman (Anderson, 1971;Buric et al, 2009;Farahani & Gogolla, 1999;Tang et al, 2020), Resonance Raman (Kiefer & Bernstein, 1972;Liu et al, 2013;Saito et al, 2003;Xie et al, 2009), Inverse Raman (Takaya et al, 2019;Yeung, 1974), Hyper Raman scattering (Babenko et al, 2020;Madzharova et al, 2017;Verdieck et al, 1970;Zhu et al, 2018) and Raman-induced Kerr effect (Ando et al, 2020;Heiman et al, 1976;Kakinuma & Shirota, 2018) are amongst various examples of Raman processes. CARS is a very effective non-linear spectroscopic technique that has been used in various applications such as temperature and concentration measurements, molecular relaxation processes, gas-phase and plasma diagnostics and femtosecond chemistry (El-Diasty, 2011;Lempert & Adamovich, 2014;Tolles et al, 1977;Zheltikov, 2000).…”

Individual Split Au Square Ring for Surface Enhanced Raman and Hyper-Raman Scattering

“…In the last two decades, the development of efficient SEHRS substrates are getting growing interest. Different kinds of Ag nanostructures, such as nanowires [12], nanodimers [13], nanorices [15], nanocavities [16], nanorice multimers [17], etc [9,11,14] have been developed. Yet, SEHRS reports about Au nanostructure substrates are still limited in literature to the best of our knowledge.…”