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Carbyne, a linear chain of carbon atoms, is the truly one-dimensional allotrope of carbon and the strongest known Raman scatterer. Here, we use tip-enhanced Raman scattering (TERS) to further enhance the Raman response of a single carbyne chain confined inside a double-walled carbon nanotube. We observe an increase of the anti-Stokes scattering by a factor of 3290 and a 22-fold enhancement of the anti-Stokes/Stokes ratio relative to far-field measurements. The power dependence of the anti-Stokes/Stokes ratio under TERS conditions is indicative of coherent Stokes–anti-Stokes scattering mediated by an excited phonon. The role of resonance effects and laser-induced heating are discussed and potential opportunities are outlined., Nano Letters, 22 (8), ISSN:1530-6984, ISSN:1530-6992

Two-dimensional transition metal dichalcogenides (2D-TMDs) are atomically thin semiconductors with a direct bandgap in monolayer thickness, providing ideal platforms for the development of exciton-based optoelectronic devices. Extensive studies on the spectral characteristics of exciton emission have been performed, but spatially resolved optical studies of 2D-TMDs are also critically important because of large variations in the spatial profiles of exciton emissions due to local defects and charge distributions that are intrinsically nonuniform. Because the spatial resolution of conventional optical microscopy and spectroscopy is fundamentally limited by diffraction, near-field optical imaging using apertured or metallic probes has been used to spectrally map the nanoscale profiles of exciton emissions and to study the effects of nanosize local defects and carrier distribution. While these unique approaches have been frequently used, revealing information on the exciton dynamics of 2D-TMDs that is not normally accessible by conventional far-field spectroscopy, a dedicated review of near-field imaging and spectroscopy studies on 2D-TMDs is not available. This review is intended to provide an overview of the current status of near-field optical research on 2D-TMDs and the future direction with regard to developing nanoscale optical imaging and spectroscopy to investigate the exciton characteristics of 2D-TMDs.

This work demonstrates the enhancement in plasmonic sensing efficacy resulting from spatially-localized functionalization on nanostructured surfaces, whereby probe molecules are concentrated in areas of high field concentration. Comparison between SERS measurements on nanostructured surfaces (arrays of nanodisks 110 and 220 nm in diameter) with homogeneous and spatially-localized functionalization with thiophenol demonstrates that the Raman signal originates mainly from areas with high field concentration. TERS measurements with 10 nm spatial resolution confirm the field distribution profiles predicted by the numerical modeling. Though this enhancement in plasmonic sensing efficacy is demonstrated with SERS, results apply equally well to any type of optical/plasmonic sensing on functionalized surfaces with nanostructuring.

Tip-enhanced Raman spectroscopy (TERS) is a powerful tool for the characterization of surfaces and 2D materials, delivering both topographical and chemical information with nanometer-scale spatial resolution. Atomic force microscopy (AFM) -TERS combines AFM with a Raman spectrometer and is a very versatile technique, capable of working in vacuum, air, and liquid, and on a variety of different samples. A metalized AFM tip is necessary in order to take advantage of the plasmonic enhancement. The most commonly used metal is Ag, thanks to its high plasmonic activity in the visible range. Unfortunately, though, the tip metallization process is still challenging and not fully reliable, yielding inconsistent enhancement factors even within the same batch of tips; as a consequence, many tips are usually prepared at once (for a single experiment), to ensure that at least one of them is sufficiently active. As the lifetime of an unprotected, Ag- coated plasmonic probe is only a few hours, the procedure is inefficient and results in a substantial waste of materials and money. In this work, we establish a cleaning routine to effectively re-use Ag-coated AFM- TERS probes, drastically reducing costs without compromising the quality of the experimental results., Applied spectroscopy, 74 (11), ISSN:0003-7028, ISSN:1943-3530

This article, a part of the larger research project of Surface-Enhanced Raman Scattering (SERS), describes an advanced study focusing on the shapes and materials of Tip-Enhanced Raman Scattering (TERS) designated to serve as part of a novel imager device. The initial aim was to define the optimal shape of the &ldquo, probe&rdquo, tip or cavity, round or sharp. The investigations focused on the effect of shape (hemi-sphere, hemispheroid, ellipsoidal cavity, ellipsoidal rod, nano-cone), and the effect of material (Ag, Au, Al) on enhancement, as well as the effect of excitation wavelengths on the electric field. Complementary results were collected: numerical simulations consolidated with analytical models, based on solid assumptions. Preliminary experimental results of fabrication and structural characterization are also presented. Thorough analyses were performed around critical parameters, such as the plasmonic metal&mdash, Silver, Aluminium or Gold&mdash, using Rakic model, the tip geometry&mdash, sphere, spheroid, ellipsoid, nano-cone, nano-shell, rod, cavity&mdash, and the geometry of the plasmonic array: cross-talk in multiple nanostructures. These combined outcomes result in an optimized TERS design for a large number of applications.

CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior FINEP - Financiadora de Estudos e Projetos, Financiadora de Estudos e Projetos INCT – Instituto nacional de ciência e tecnologia (Antigo Instituto do Milênio) Outra Agência On nanomaterials characterization, the evolution from the broadly utilized micro-Raman spectroscopy to a nanoscale regime is taking place with the improvements in tip-enhanced Raman spectroscopy (TERS). It is not clear, however, to which extent protocols developed within the diffraction-limited far-field configuration apply to the near-field regime. Defects in graphene nanoflakes are investigated in this work in both micro and nano regimes, showing that the Raman characteristics utilized to quantify defects in the far-field regime actually change in the presence of the TERS tip, generating incompatible results. The micro-tonano spectral mismatch can be modeled using a theory of spatial coherence in near-field Raman scattering, from which a parameterization procedure can be derived in order to obtain consistent results. The incompatibilities observed here for graphene should also happen in other structures relevant to nanoscience and nanotechnology when explored in the nano-Raman regime, and they can be resolved similarly.

Transferring CVD graphene using surfactantprotectedAu nanoparticles (Au NPs) avoids the use of PMMAand opens new ways of building heterojunctions for TERS andSERS applications. Thermal treatment removes organics fromthe Au NPs and leads to larger nanoparticles and theformation of networks, dimmers, and nanoplates of variousshapes (circles, hexagons, and triangles). Raman and HRTEMrevealed bilayer graphene and Moirépatterns as determined bythe 2D band and dislocated atomic layers, respectively. TERS performed on the heterojunction exhibits a reversible increase infrequency and sharpening of the characteristic bands in graphene along with the exaltation of bands such as D + D′. A closeexamination into a single triangular-shape nanoplate reveals that the most irregular area of the nanoplate is consistent with thehigher Raman enhancement of Rh6G when compared to other areas of the same feature. This work may shed light onto newways of transferring graphene, fundamental aspects concerning local strains in the heterojunction, and SERS on a single Aunanostructure. Fil: Pérez, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina Fil: Dalfovo, Maria Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina Fil: Troiani, Horacio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina Fil: Soldati, Analía Leticia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina Fil: Lacconi, Gabriela Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina Fil: Ibañez, Francisco Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentina

Long linear carbon chains encapsulated inside carbon nanotubes are a very close realization of carbyne, the truly one-dimensional allotrope of carbon. Here we study individual pairs of double-walled carbon nanotubes and encapsulated linear carbon chains by tip-enhanced Raman scattering. We observe that the radial breathing mode of the inner nanotube correlates with the frequency of the carbon chain's Raman mode, revealing that the nanotube chirality determines the vibronic and electronic properties of the encapsulated carbon chain. We provide the missing link that connects the properties of the encapsulated long linear carbon chain with the structure of the host nanotube., Comment: keywords: linear carbon chains; carbyne; carbon nanotubes; tip-enhanced Raman scattering; TERS; Significant changes compared to first version of the manuscript. Current version includes Supporting Information

Tip-enhanced Raman spectroscopy (TERS) has become a well-applied technique for nanospectroscopy, allowing for single molecule sensitivity with sub-nanometer spatial resolution. The demand for efficient, reproducible and cost-effective probes for TERS is increasing. Here we report on a new electrochemical etching protocol to fabricate TERS tips starting from 125 µm diameter gold wires in a reproducible way. The process is reliable (50% of the tips have radius of curvature 5 are observed. TERS mapping with a spatial resolution of 5 nm is demonstrated.

Type 2 diabetes mellitus is characterized by the pathological deposition of fibrillized protein, known as amyloids. It is thought that oligomers and/ or amyloid fibrils formed from human islet amyloid polypeptide (hIAPP or amylin) cause cell death by membrane damage. The molecular structure of hIAPP amyloid fibrils is dominated by beta-sheet structure, as probed with conventional infrared and Raman vibrational spectroscopy. However, with these techniques it is not possible to distinguish between the core and the surface structure of the fibrils. Since the fibril surface crucially affects amyloid toxicity, it is essential to know its structure. Here the surface molecular structure and amino acid residue composition of hIAPP fibrils are specifically probed with nanoscale resolution using tip-enhanced Raman spectroscopy (TERS). The fibril surface mainly contains unordered or alpha-helical structures, in contrast to the beta-sheet-rich core. This experimentally validates recent models of hIAPP amyloids based on NMR measurements. Spatial mapping of the surface structure reveals a highly heterogeneous surface structure. Finally, TERS can probe fibrils formed on a lipid interface, which is more representative of amyloids in vivo.

Chimia, 73 (6), ISSN:0009-4293

Ge-on-Si and Ge-on-insulator (GeOI) are the most promising materials for the next-generation nanoelectronics that can be fully integrated with silicon technology. To this day, the fabrication of Ge-based transistors with a n-type channel doping above 5 × 1019 cm−3 remains challenging. Here, we report on n-type doping of Ge beyond the equilibrium solubility limit (ne ≈ 6 × 1020 cm−3) together with a nanoscale technique to inspect the dopant distribution in n++-p junctions in GeOI. The n++ layer in Ge is realized by P+ ion implantation followed by millisecond-flashlamp annealing. The electron concentration is found to be three times higher than the equilibrium solid solubility limit of P in Ge determined at 800 °C. The millisecond-flashlamp annealing process is used for the electrical activation of the implanted P dopant and to fully suppress its diffusion. The study of the P activation and distribution in implanted GeOI relies on the combination of Raman spectroscopy, conductive atomic force microscopy, and secondary ion mass spectrometry. The linear dependence between the Fano asymmetry parameter q and the active carrier concentration makes Raman spectroscopy a powerful tool to study the electrical properties of semiconductors. We also demonstrate the high electrical activation efficiency together with the formation of ohmic contacts through Ni germanidation via a single-step flashlamp annealing process.Ge-on-Si and Ge-on-insulator (GeOI) are the most promising materials for the next-generation nanoelectronics that can be fully integrated with silicon technology. To this day, the fabrication of Ge-based transistors with a n-type channel doping above 5 × 1019 cm−3 remains challenging. Here, we report on n-type doping of Ge beyond the equilibrium solubility limit (ne ≈ 6 × 1020 cm−3) together with a nanoscale technique to inspect the dopant distribution in n++-p junctions in GeOI. The n++ layer in Ge is realized by P+ ion implantation followed by millisecond-flashlamp annealing. The electron concentration is found to be three times higher than the equilibrium solid solubility limit of P in Ge determined at 800 °C. The millisecond-flashlamp annealing process is used for the electrical activation of the implanted P dopant and to fully suppress its diffusion. The study of the P activation and distribution in implanted GeOI relies on the combination of Raman spectroscopy, conductive atomic force microscopy, an...

We firstly, in this review, introduce the optical properties of plasmonic metals, and then focus on introducing the unique optical properties of the noble metal–metal-oxide hybrid system by revealing the physical mechanism of plasmon–exciton interaction, which was confirmed by theoretical calculations and experimental investigations. With this noble metal–metal-oxide hybrid system, plasmonic nanostructure–semiconductor exciton coupling interactions for interface catalysis has been analyzed in detail. This review can provide a deeper understanding of the physical mechanism of exciton–plasmon interactions in surface catalysis reactions.

Phase segregation of coadsorbed thiol molecules on a gold surface was investigated with nanoscale chemical imaging using tip-enhanced Raman spectroscopy (TERS). Samples were prepared using mixed solutions containing thiophenol (PhS) and an oligomeric phenylene-ethynylene (OPE) thiol, with 10:1, 2:1, and 1:1 molar ratios. Phase segregation into domains with sizes from ≈30 to 240 nm is observed with these molar ratios. A comparison of TERS images with different pixel sizes indicates that a pixel size bigger than 15 nm is not reliable in defining nanodomains, because of undersampling. In this study, the formation of nanodomains was clearly evident based on the molecular fingerprints provided by TERS, while ambient scanning tunneling microscopy (STM) was not capable of discerning individual domains via their apparent height difference. TERS therefore allows to image nanodomains in binary self-assembled monolayers, which are invisible to methods solely relying on topographic or electron density characteristics of self-assembled monolayers. Moreover, TERS mapping provides statistical data to describe the distribution of molecules on the sample surface in a well-defined manner. Peak ratio histograms of selected TERS signals from samples prepared with different mixing ratios give a better understanding of the adsorption preference of the thiols studied, and the relationship of their mixing ratio in solution and adsorbed on the surface., Analytical and Bioanalytical Chemistry, 407 (27), ISSN:1618-2650, ISSN:1618-2642

We used scanning tunneling microscopy–tip-enhanced Raman spectroscopy (STM-TERS) to study the polarization properties of near-field scattering on a crystalline material as well as on a dye adsorbate. The measurements on a (111)-oriented c-Si sample were found to be well described by a recently proposed model for TERS and allowed for a characterization of the polarization properties of the tips used. The tip enhancement was stronger for excitation radiation having a field component along the tip axis for both types of samples. A non-negligible enhancement was also found for the field component perpendicular to the tip axis.

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2007, Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2007, Bu çalışmada, homojen bir yarı-uzaya gömülü mükemmel iletken bir cismin konumunun ve şeklinin belirlenmesi problemi ele alınmıştır. Gerçeğe daha yakın olan ancak çok daha yoğun hesaplama gerektiren üç boyutlu duruma giriş niteliğinde olmak üzere, iki boyutlu daha basit durum üzerinde durulmuştur. Önce katmanlı ortam için Green fonksiyonu elde edilmiş, ardından saçılan alan, birleşik tek ve çift tabaka potansiyeller olarak, Green fonksiyonu ve potansiyel yoğunluğu cinsinden ifade edilmiştir. Bu saçılan alan ifadesinin sınır değerleri için, Dirichlet sınır koşulu ve sıçrama bağıntıları kullanılarak bir integral denklem elde edilmiş, bu denklem Nyström yöntemi aracılığıyla çözülmüştür. Daha sonra, cismin konumunu ve şeklini elde edebilmek için, Green fonksiyonunun karşılıklılık ilişkisini kullanan bir nokta-kaynak yöntemi tanıtılmıştır. En sonunda, yöntemin gerçekleştirilmesinin kimi etkin biçimleri gösterilmiş ve iki boyutlu durum için yapılan sayısal çalışmaların sonuçlarından örnekler verilmiştir., In this study, we consider the problem of reconstructing the location and shape of a bounded perfectly conducting obstacle which is buried in a homogeneous half space. We restrict our attention to the simplest case of two dimensions, which serves as a first step to the more involved and computationally much more expensive three-dimensional realistic situation. First we represent the Green’s function for the layered medium. Then, scattered field is represented as a combined single- and double-layer potential in terms of the Green’s function and a potential density. An integral equation is obtained for the boundary values of this scattered field expression by using Dirichlet boundary condition and jump relations. The integral equation is solved for the potential density by using Nyström method. Then, a point-source method which uses the reciprocity relation of the Green’s function for the reconstruction of the location and shape of the obstacle is established. Finally, we describe some efficient implementation of the method and show numerical examples in two dimensions., Yüksek Lisans, M.Sc.

Objective: We investigated whether the INTERMED, a generic instrument for assessing biopsychosocial case complexity and direct care, identifies organ transplant patients at risk of unfavourable post-transplant development by comparing it to the Transplant Evaluation Rating Scale (TERS), the established measure for pretransplant psychosocial evaluation. Method: One hundred nineteen kidney, liver, and heart transplant candidates were evaluated using the INTERMED, TERS, SF-36, EuroQol, Montgomery-Asberg Depression Rating Scale (MADRS), and Hospital Anxiety 8( Depression Scale (HADS). Results: We found significant relationships between the INTERMED and the TERS scores. The INTERMED highly correlated with the HADS, MADRS, and mental and physical health scores of the SF-36 Health Survey. Conclusions: The results demonstrate the validity and usefulness of the INTERMED instrument for pretransplant evaluation. Furthermore, our findings demonstrate the different qualities of INTERMED and TERS in clinical practice. The advantages of the psychiatric focus of the TERS and the biopsychosocial perspective of the INTERMED are discussed in the context of current literature on integrated care.