Sidewall angle tuning in focused electron beam-induced processing

• Sangeetha Hari,
• Willem F. van Dorp,
• Johannes J. L. Mulders,
• Piet H. F. Trompenaars,
• Pieter Kruit and
• Cornelis W. Hagen

Beilstein J. Nanotechnol. 2024, 15, 447–456, doi:10.3762/bjnano.15.40

• incidence x [9]; thus, the etching is enhanced by the same factor. Directing the beam to a fixed position on the sloped sidewall, the Gaussian profile, multiplied by the local SE-yield enhancement factor, governs the etching of the deposit, given a fixed etching strength. Figure 2b illustrates the evolution

Potential of a deep eutectic solvent in silver nanoparticle fabrication for antibiotic residue detection

• Le Hong Tho,
• Bui Xuan Khuyen,
• Ngoc Xuan Dat Mai and
• Nhu Hoa Thi Tran

Beilstein J. Nanotechnol. 2024, 15, 426–434, doi:10.3762/bjnano.15.38

• ). At the limit of detection (LOD) of 10−8 M, the SERS spectrum clearly shows emerging peaks, the highest enhancement factor (EF) of which reaches 6.29 × 107, proving the NFT residue tracing capability of the Ag NPs-DES substrate. These peaks correspond to vibrations of characteristic groups of NFT as

Silver-based SERS substrates fabricated using a 3D printed microfluidic device

• Phommachith Sonexai,
• Minh Van Nguyen,
• Bui The Huy and
• Yong-Ill Lee

Beilstein J. Nanotechnol. 2023, 14, 793–803, doi:10.3762/bjnano.14.65

• particles. The electric field is enhanced, and the Raman enhancement factor (EF) can reach 106 [6]. The induced amplification of the local field by plasmonic coupling occurs in nanometer-scale regions around the metal particles, the so-called electromagnetic “hot spots”. The chemical mechanism suggests the

• applying the 3σ/s method, where σ is the standard deviation of the blank and s is the slope of the linear regression equation, the limit of detection was found to be 1.94 × 10−10 M. The SERS substrates showed an enhancement factor (EF) of 8.59 × 106 for the 621 cm−1 peak at an RhB concentration of 10−9 M

• . The calculation details for the EF can be found in the “Enhancement factor calculation” section of Supporting Information File 1. To investigate the uniformity of the SERS substrate, Raman mapping was performed at 16 measuring positions in an area of 100 µm × 100 µm . RhB with a concentration of 10−5

SERS performance of GaN/Ag substrates fabricated by Ag coating of GaN platforms

• Magdalena A. Zając,
• Bogusław Budner,
• Malwina Liszewska,
• Bartosz Bartosewicz,
• Łukasz Gutowski,
• Jan L. Weyher and
• Bartłomiej J. Jankiewicz

Beilstein J. Nanotechnol. 2023, 14, 552–564, doi:10.3762/bjnano.14.46

• PLD-made GaN/Ag substrates, the estimated enhancement factors were higher than for MS-made substrates with a comparable thickness of the Ag layer. In the best case, the PLD-made GaN/Ag substrate exhibited an approximately 4.4 times higher enhancement factor than the best MS-made substrate. Keywords

• average intensity of the peak at 1078 cm−1 and the standard deviation of intensity allowed us to determine which samples have the highest enhancement factor (EF) of the Raman signal and a high density of hot spots on the surface. The enhancement factor was calculated according to the formula described in

• in each spectrum represents the standard deviation of the signal. SEM images of GaN/Ag substrates, MS_2_RT (left) and PLD_2_RT (right), with a comparable thickness of the reference Ag layer (423 ± 5 nm and 429 ± 14 nm, respectively) and with the highest enhancement factor in the group of samples

Quasi-guided modes resulting from the band folding effect in a photonic crystal slab for enhanced interactions of matters with free-space radiations

• Kaili Sun,
• Yangjian Cai,
• Uriel Levy and
• Zhanghua Han

Beilstein J. Nanotechnol. 2023, 14, 322–328, doi:10.3762/bjnano.14.27

•  4c presents the maximum local electric field magnitude normalized to that of the incident plane wave. It can be seen that an enhancement factor of 312 can be achieved for an incident angle of 3° along the x axis. This number decreases to 156 and 107 for incident angles of 6° and 9° along the x axis

Revealing local structural properties of an atomically thin MoSe₂ surface using optical microscopy

• Lin Pan,
• Peng Miao,
• Anke Horneber,
• Alfred J. Meixner,
• Pierre-Michel Adam and
• Dai Zhang

Beilstein J. Nanotechnol. 2022, 13, 572–581, doi:10.3762/bjnano.13.49

• can see that SHG intensity, photoluminescence, and Raman enhancement are strongly related to the local structure of the MoSe2 flake. Discussion A quantitative analysis of the enhancement factor of Raman modes of CuPc is shown in Figure 3a. Specifically, the vibrational modes located at 1339, 1449, and

• 1527 cm−1 are assigned to the C–C and N–C stretching vibrations of the isoindole ring [34][35]. The 746 cm−1 vibrational mode originates from the metal-bound N–M stretching vibration, and the 1138 cm−1 mode is attributed to the deformation of the isoindole ring system [36]. The Raman enhancement factor

• is calculated by dividing the Raman intensity of CuPc at the flake center by that on the SiO2/Si substrate. Interestingly, although excitation with radial polarization gives a stronger Raman intensity (e.g., 1527 cm−1) than excitation with azimuthal polarization, the enhancement factor of each Raman

Zinc oxide nanostructures for fluorescence and Raman signal enhancement: a review

• Ioana Marica,
• Fran Nekvapil,
• Maria Ștefan,
• Cosmin Farcău and
• Alexandra Falamaș

Beilstein J. Nanotechnol. 2022, 13, 472–490, doi:10.3762/bjnano.13.40

• chemical enhancement from the electronic interaction between the analyte and the nanosurface [59]. The electromagnetic enhancement factor (EF) can reach up to eleven orders of magnitude in the “hot spots” of the nanosubstrate [60][61], while the chemical EF usually has a value between 10 and 103. Since the

• SERS activity of ZnO is weak [15] it can be improved by doping with heavy elements or by combining ZnO nanostructures with noble metals, thus increasing the electromagnetic or the chemical enhancement factor. Combined nanomaterials can offer increased SERS amplification due to both metal-induced EM and

• relevant descriptors of any SERS substrate is the signal enhancement factor (EF), which describes the enhancement of the Raman signal of target molecules when adsorbed on the SERS substrate relative to the conventional Raman signal of the same number of molecules. The EF is generally calculated according

Sputtering onto liquids: a critical review

• Anastasiya Sergievskaya,
• Adrien Chauvin and
• Stephanos Konstantinidis

Beilstein J. Nanotechnol. 2022, 13, 10–53, doi:10.3762/bjnano.13.2

The role of deep eutectic solvents and carrageenan in synthesizing biocompatible anisotropic metal nanoparticles

• Nabojit Das,
• Akash Kumar and
• Raja Gopal Rayavarapu

Beilstein J. Nanotechnol. 2021, 12, 924–938, doi:10.3762/bjnano.12.69

• -enhanced Raman scattering (SERS) when doped with rhodamine B (RhB). The enhancement factor produced by these gold nanoflowers was estimated to be 1.09 × 105 regarding pure RhB. The value of the enhancement factor is up to par with the intensively branched gold nanoparticles and is even greater than some of

Surface-enhanced Raman scattering of water in aqueous dispersions of silver nanoparticles

• Paulina Filipczak,
• Krzysztof Hałagan,
• Jacek Ulański and
• Marcin Kozanecki

Beilstein J. Nanotechnol. 2021, 12, 497–506, doi:10.3762/bjnano.12.40

• Raman scattering (SERS) effect. In this work, we show the SERS effect for water molecules in the dispersion of silver nanoparticles (AgNPs) without any external electrical field. An enhancement factor was estimated to be (4.8 ± 0.8) × 106 for an excitation wavelength of 514.5 nm and for AgNPs with an

• the Section SI3 in the Supporting Information section of [35].). The classic enhancement factor (EF) for a given substrate is given by the formula [41]: where ISERS and IRS denote the intensity of the SERS signal and the normal Raman scattering signal, respectively. The values Nsurf and Nvol are the

• calculate the EF. As all measurements were performed under the same conditions, all calculations, for simplicity, were done for 1 dm3 of the samples (water and AgNPs blue dispersion). The enhancement factor for AgNPs blue was calculated by using Equation 1 as follows: ISERS and IRS are integral intensities

Boosting of photocatalytic hydrogen evolution via chlorine doping of polymeric carbon nitride

• Malgorzata Aleksandrzak,
• Michalina Kijaczko,
• Wojciech Kukulka,
• Daria Baranowska,
• Martyna Baca,
• Beata Zielinska and
• Ewa Mijowska

Beilstein J. Nanotechnol. 2021, 12, 473–484, doi:10.3762/bjnano.12.38

• the H2 evolution rate after three cycles, indicating the stability of the catalyst. Table 4 presents a comparative study of Cl-PCN with catalysts doped with Cl and other elements which have been reported in the literature. The table presents a broad range of the enhancement factor of the hydrogen

Fabrication of nano/microstructures for SERS substrates using an electrochemical method

• Jingran Zhang,
• Tianqi Jia,
• Xiaoping Li,
• Junjie Yang,
• Zhengkai Li,
• Guangfeng Shi,
• Xinming Zhang and
• Zuobin Wang

Beilstein J. Nanotechnol. 2020, 11, 1568–1576, doi:10.3762/bjnano.11.139

• the thickness of Au film coating is held constant, the Raman intensity on the structured Mg substrates is about five times higher after a treatment time of 1 min when compared with other treatment times. The SERS enhancement factor ranges from 106 to 1.75 × 107 under these experimental conditions

• factor of R6G molecules on the pyramid structure was about 105. Wu et al. [26] machined nanohole array structures using EBL and lift-off methods. The diameter of the nanoholes ranged from 90 to 585 nm, and the gap between adjacent nanoholes ranged from 125 to 585 nm. An enhancement factor of 8 × 106 was

• spots decreases. Sivashanmugan et al. [32] employed FIB technology to prepare nanostructures on silicon surfaces, which were then coated with Au and Ag films to generate SERS substrates. The enhancement factor range of R6G using the substrate was between 2.62 × 106 and 1.74 × 107. Gao et al. [33

Highly sensitive detection of estradiol by a SERS sensor based on TiO₂ covered with gold nanoparticles

• Andrea Brognara,
• Ili F. Mohamad Ali Nasri,
• Beatrice R. Bricchi,
• Andrea Li Bassi,
• Caroline Gauchotte-Lindsay,
• Matteo Ghidelli and
• Nathalie Lidgi-Guigui

Beilstein J. Nanotechnol. 2020, 11, 1026–1035, doi:10.3762/bjnano.11.87

• soaking in HAuCl4 solution, as composite SERS substrates for the detection of methylene blue. They reported a successful SERS enhancement, compared to bare Si substrates, with an enhancement factor of ca. 106 and a lower detection limit of 100 nM. Li et al. [15] studied Au NP-coated TiO2 nanotube arrays

• proximity of the NPs, which is higher for higher Au coverages (Table 1). The electric field between two nanoparticles is extraordinarily enhanced when the NPs are close to each other [7][40] and form so-called hot spots. To compare the enhancement capacity of the TiO2/Au samples, the enhancement factor (EF

• to different shapes, sizes and distributions of the Au NPs. The TiO2/Au 6 nm deposited at 12 Pa and annealed for 2 h at 500 °C gives an enhancement factor (EF) of 3.7·105 and 3.4·105 at, respectively, 1080 and 1590 cm−1. These high EF values for two distant wavelengths has been exploited to test the

Hexagonal boron nitride: a review of the emerging material platform for single-photon sources and the spin–photon interface

• Stefania Castelletto,
• Faraz A. Inam,
• Shin-ichiro Sato and
• Alberto Boretti

Beilstein J. Nanotechnol. 2020, 11, 740–769, doi:10.3762/bjnano.11.61

Label-free highly sensitive probe detection with novel hierarchical SERS substrates fabricated by nanoindentation and chemical reaction methods

• Jingran Zhang,
• Tianqi Jia,
• Yongda Yan,
• Li Wang,
• Peng Miao,
• Yimin Han,
• Xinming Zhang,
• Guangfeng Shi,
• Yanquan Geng,
• Zhankun Weng,
• Daniel Laipple and
• Zuobin Wang

Beilstein J. Nanotechnol. 2019, 10, 2483–2496, doi:10.3762/bjnano.10.239

• surface-enhanced Raman scattering (SERS) substrates. Recently, in order to obtain a higher enhancement factor at a lower detection limit, hierarchical structures, including nanostructures and nanoparticles, appear to be viable SERS substrate candidates. Here we describe a novel method integrating the

• . The feasibility of the hierarchical SERS substrate is verified using R6G molecules. Finally, the enhancement factor using malachite green molecules was found to reach 5.089 × 109, which demonstrates that the production method is a simple, reproducible and low-cost method for machining a highly

• where the optimized enhancement factor was determined to be 8.6 × 106. Zhong et al. [11] presented nanoparticles formed by HAuCl3 and sodium citrate solutions on the poly(methyl methacrylate) (PMMA) template as a transparent SERS substrate. Then, malachite green at a concentration of 0.1 nmol/L was

Deterministic placement of ultra-bright near-infrared color centers in arrays of silicon carbide micropillars

• Stefania Castelletto,
• Abdul Salam Al Atem,
• Faraz Ahmed Inam,
• Hans Jürgen von Bardeleben,
• Sophie Hameau,
• Ahmed Fahad Almutairi,
• Gérard Guillot,
• Shin-ichiro Sato,
• Alberto Boretti and
• Jean Marie Bluet

Beilstein J. Nanotechnol. 2019, 10, 2383–2395, doi:10.3762/bjnano.10.229

• ], nanopillars in 4H-SiC formed by reactive ion etching (RIE) for the improvement of the VSi emission collection efficiency [50], and the use of a solid immersion lens (SIL) for an enhancement factor of three of single VSi [4]. Recent results of the successful enhancement of VSi in 4H-SiC based on nanopillars

• [50] provided an equivalent enhancement (factor of three) of SIL but with a smaller footprint and better scalability. The sensitivity of quantum magnetic sensing using spin carrying color centers undergoing ODMR as probes, such as VSi, is currently of the order of δB ≈ 10μT/√Hz and can be improved in

• ± 0.09 mW, with a saturation count rate of ϕ∞ = 373 ± 14 kcts/s. In sample 1 we observed for one specific pillar an enhancement factor of 14 at saturation in terms of count rate and a reduction of the optical excitation power by a factor of 5.6. For VSi a count rate of 22 kcts/s of a single emitter in a

A silver-nanoparticle/cellulose-nanofiber composite as a highly effective substrate for surface-enhanced Raman spectroscopy

• Yongxin Lu,
• Yan Luo,
• Zehao Lin and
• Jianguo Huang

Beilstein J. Nanotechnol. 2019, 10, 1270–1279, doi:10.3762/bjnano.10.126

• detection limit down to the sub-attomolar (1 × 10−16 M) level and an enhancement factor of 3 × 106 were achieved by using Rhodamine 6G as the analyte. Moreover, this substrate was applied to monitor the molecular recognition through multiple hydrogen bonds in between nucleosides of adenosine and thymidine

• to the fourth-power dependence of the enhancement factor on the electric field intensity, the enhancement factor of this substrate was estimated to be ca. 3 × 106. Compared with previously reported cellulose-based SERS substrates, our current substrate shows a better SERS activity. For example, the

Revisiting semicontinuous silver films as surface-enhanced Raman spectroscopy substrates

• Malwina Liszewska,
• Bogusław Budner,
• Małgorzata Norek,
• Bartłomiej J. Jankiewicz and
• Piotr Nyga

Beilstein J. Nanotechnol. 2019, 10, 1048–1055, doi:10.3762/bjnano.10.105

• , reflectance decreases for wavelengths in the range of about one micrometer) without the need for expensive and time-consuming structural characterization. This could be used as a quick method for initial optimization of SSF thickness for high SERS signal. Calculation of the SERS enhancement factor of a SERS

• substrate is extremely difficult since a proper reference sample is needed and there is an ongoing debate in the community regarding the appropriate procedures [59]. We decided to estimate the lower limit of the enhancement factor by adopting an approach similar to one used in the reference [20]. We

• the Raman band at 1080 cm−1 by the peak-to-peak noise of the measurement on the sample I we obtained a lower limit of the enhancement factor of about 630. Conclusion We have fabricated semicontinuous silver films with various morphologies, ranging from isolated particles, through percolated to almost

Correlation of surface-enhanced Raman scattering (SERS) with the surface density of gold nanoparticles: evaluation of the critical number of SERS tags for a detectable signal

• Vincenzo Amendola

Beilstein J. Nanotechnol. 2019, 10, 1016–1023, doi:10.3762/bjnano.10.102

• scattering (SERS), the Raman scattering cross-section of molecules adsorbed on the surface of plasmonic nanostructures is enormously increased compared to the same isolated molecules [1][2][3][4][5]. In particular, the SERS enhancement factor can reach values as high as 1012, which can be attributed to two

• local field enhancement in a AuNT with structure reproducing the aggregate in Figure 1B. In particular, the SERS enhancement factor (GSERS) was obtained from the 4th power of the ratio between the local electric field, Eloc, in the proximity to the surface of the metal nanostructure and the incident

Fabrication of silver nanoisland films by pulsed laser deposition for surface-enhanced Raman spectroscopy

• Bogusław Budner,
• Mariusz Kuźma,
• Barbara Nasiłowska,
• Bartosz Bartosewicz,
• Malwina Liszewska and
• Bartłomiej J. Jankiewicz

Beilstein J. Nanotechnol. 2019, 10, 882–893, doi:10.3762/bjnano.10.89

• adsorbed on them. SERS enhancement factors are shown to depend on the SNIF morphology, which is modified by changes of the deposition conditions. The highest enhancement factor in the range of 105 was achieved for SNIFs that have oval and circular silver nanoislands with small distances between them

• sections of this article suggest that the distances between the silver nanoislands are increasing as the temperature of the substrate increases. This conclusion is consistent with the observed reduction of the enhancement factor (EF) achieved for the Raman signal when the substrate temperature rises

• deviation. The relative intensity deviation ranges, for both excitation wavelengths, from 12% to 20%, which means that the layers obtained are characterized by a greater uniformity of the enhancement factor of the Raman signal. In turn, the use of a substrate temperature of 340 ± 3 °C, resulting in a high

Features and advantages of flexible silicon nanowires for SERS applications

• Hrvoje Gebavi,
• Vlatko Gašparić,
• Dubravko Risović,
• Nikola Baran,
• Paweł Henryk Albrycht and
• Mile Ivanda

Beilstein J. Nanotechnol. 2019, 10, 725–734, doi:10.3762/bjnano.10.72

• resonant laser excitation of analyte molecules with differential cross section of ca. 10−27 cm2/sr, a SERS enhancement factor (EF) of 108 would be adequate for single-molecule detection. Under non-resonant conditions and/or for lower cross sections (ca. 10−30 cm2/sr ) EF values above 1011 are required [4

• has a higher surface tension than ethanol and, consequently, pulls the SiNWs together stronger causing a larger SERS enhancement. Since the SERS effect decreases with distance [43], bringing the SiNWs closer significantly improves the analyte detection. In [2] the author assumed that the enhancement

• factor increases approximately as d−8 in the case of two metal nanoparticles with the polarization along the particle axis, which can be roughly applied to the case of two nanowires. However, in the reported substrates SiNWs are randomly oriented and the polarization measurement was not tested in detail

Biomimetic synthesis of Ag-coated glasswing butterfly arrays as ultra-sensitive SERS substrates for efficient trace detection of pesticides

• Guochao Shi,
• Mingli Wang,
• Yanying Zhu,
• Yuhong Wang,
• Xiaoya Yan,
• Xin Sun,
• Haijun Xu and
• Wanli Ma

Beilstein J. Nanotechnol. 2019, 10, 578–588, doi:10.3762/bjnano.10.59

• . nanohybrids with thick Ag nanofilms provide a substantial contribution to SERS enhancement. Measuring the SERS performance with crystal violet (CV), the Ag-G.b. nanohybrids with the sputtering time of 20 min (Ag-G.b.-20) shows the highest enhancement performance with an enhancement factor (EF) of up to 2.96

• a dynamic electron transfer between probe molecules and nanostructures. In contact with the nanostructures, the adsorbed molecules exhibit a larger scattering cross section, thus enhancing the Raman signal intensity efficiently [5]. However, CE only contributes to the enhancement factor (EF) up to

• time-domain simulation To better evaluate the SERS enhancement performance of the Ag-G.b.-20 substrates, an enhancement factor (EF) has been estimated based on Equation 1 [1][20]: where the ISERS and Ibulk are the integrated intensities of a same Raman peak in the SERS spectrum and bulk Raman spectrum

Quantification and coupling of the electromagnetic and chemical contributions in surface-enhanced Raman scattering

• Yarong Su,
• Yuanzhen Shi,
• Ping Wang,
• Jinglei Du,
• Markus B. Raschke and
• Lin Pang

Beilstein J. Nanotechnol. 2019, 10, 549–556, doi:10.3762/bjnano.10.56

• reference to estimate the SERS enhancement factor. All spectra were recorded with 5 s acquisition time. The silicon phonon Raman response at 520.7 cm−1 was used to calibrate the spectrometer. Results SERS spectra The spectral range of 900–1200 cm−1 was selected for the study of three characteristic Raman

• increase the local field enhancement in the transition from planar to nanostructured substrates of variable SERS enhancement, the intensity ratios of I(ω2)/I(ω1) and I(ω3)/I(ω1) remain largely constant within the uncertainty of the experiment. Enhancement factor calculation To estimate the underlying CE

• and EM enhancement factors, the Raman spectrum of neat benzenethiol is used as reference. All measurements were normalized to account for differences in surface coverage, laser power, and acquisition time, before enhancement factor calculation (for details see Supporting Information File 1). The Raman

Controlling surface morphology and sensitivity of granular and porous silver films for surface-enhanced Raman scattering, SERS

• Sherif Okeil and
• Jörg J. Schneider

Beilstein J. Nanotechnol. 2018, 9, 2813–2831, doi:10.3762/bjnano.9.263

• reducing plasma results in the formation of complex three-dimensional silver morphologies showing a huge enhancement factor due to the formation of SERS hot spots. The SERS enhancement of the as-sputtered 200 nm silver film is greatly enhanced by an appropriate plasma treatment reaching about 30-fold

Low cost tips for tip-enhanced Raman spectroscopy fabricated by two-step electrochemical etching of 125 µm diameter gold wires

• Antonino Foti,
• Francesco Barreca,
• Enza Fazio,
• Cristiano D’Andrea,
• Paolo Matteini,
• Onofrio Maria Maragò and
• Pietro Giuseppe Gucciardi

Beilstein J. Nanotechnol. 2018, 9, 2718–2729, doi:10.3762/bjnano.9.254

• times of approximately 2 min. The tips can be easily manipulated and safely mounted, by gluing or clamping them into STM- or ShF-based TERS setups. The good performance of the tips is highlighted by TERS spectra of dyes, pigments and biomolecules. The enhancement factor in the range of 104–105 was found

• contact with the surface Figure 8 (black line). After each TERS measurement, the tip is retracted from the sample and its emission is mapped in order to be sure the TERS signal does not come from molecules adsorbed on the tip apex. Evaluation of the enhancement factor An estimation of the enhancement

• factor (EF) can be given by comparing the TERS signal increase with respect to the Raman signal measured when the tip is out of contact (far-field excitation conditions), normalizing to the different areas probed in each case [71]: where INF is the near-field TERS signal, IFF is the far-field Raman