Determining by Raman spectroscopy the average thickness and N-layer-specific surface coverages of MoS₂ thin films with domains much smaller than the laser spot size

• Felipe Wasem Klein,
• Jean-Roch Huntzinger,
• Vincent Astié,
• Damien Voiry,
• Romain Parret,
• Houssine Makhlouf,
• Sandrine Juillaguet,
• Jean-Manuel Decams,
• Sylvie Contreras,
• Périne Landois,
• Ahmed-Azmi Zahab,
• Jean-Louis Sauvajol and
• Matthieu Paillet

Beilstein J. Nanotechnol. 2024, 15, 279–296, doi:10.3762/bjnano.15.26

• modes is proposed to evaluate the surface coverage for each N (i.e., the ratio between the surface covered by exactly N layers and the total surface) in DLI-PP-CVD MoS2 samples. Keywords: molybdenum disulfide; number of layers; Raman spectroscopy; thin film; transition metal dichalcogenides

• , in DLI-PP-CVD samples. Results and Discussion Experimental procedure To define a robust experimental Raman protocol to evaluate the thickness of a MoS2 flake (i.e., its number of layers, N), it is first necessary to specify some parameters that can have a direct influence on the quality and accuracy

• symmetry for a monolayer (A1g for bulk). These modes are located around 385 and 405 cm−1, respectively, in neutral and defect-free MoS2 monolayers [33][34]. More precisely, in MoS2 multilayers, the symmetries of these phonon modes are E′ and A′1 for an odd number of layers, and Eg and A1g for an even

Density functional theory study of Au-fcc/Ge and Au-hcp/Ge interfaces

• Olga Sikora,
• Małgorzata Sternik,
• Benedykt R. Jany,
• Franciszek Krok,
• Przemysław Piekarz and
• Andrzej M. Oleś

Beilstein J. Nanotechnol. 2023, 14, 1093–1105, doi:10.3762/bjnano.14.90

• ], that is, by combining two fragments of the lattice planes oriented as in Figure 1a,b. The resulting mismatch ε defined as is only 2.0%, that is, the heterostructure is almost strain-free. As only four Au atoms and two Ge atoms form a single layer of this interface, one can easily increase the number of

• layers in the supercell. In variant T1 of the considered heterostructure, the Au atoms are at maximum distance from the Ge atoms, while in variant T2 some of the gold atoms are located on the top of Ge sites. Our preliminary calculations indicated that variant T1 is preferred, and we conducted

On the use of Raman spectroscopy to characterize mass-produced graphene nanoplatelets

• Keith R. Paton,
• Konstantinos Despotelis,
• Naresh Kumar,
• Piers Turner and
• Andrew J. Pollard

Beilstein J. Nanotechnol. 2023, 14, 509–521, doi:10.3762/bjnano.14.42

• lateral size of 218 nm. We did not attempt to give a number of layers for these flakes. Yet, we do note that while the natural interlayer spacing for graphite is 0.34 nm, it has been reported previously that for similarly produced flakes, monolayer flakes had a measured thickness of 2 nm, with each

• metrics have been presented by Backes et al. [13] to quantify the mean number of layers from Raman spectra measurements. The first of these (M1) is based on the I2D/IG ratio as calculated above, and an empirical fit to the mean number of layers N was found as The second metric (M2) is based on the ratio

• , ω2 = 2689 cm−1. The ratio of the intensities at these two locations is then normalised to the ratio from the parent graphite, such that The mean number of layers per flake can then be calculated according to An alternative approach has been proposed, based on the change in shape of the 2D band as the

Conjugated photothermal materials and structure design for solar steam generation

• Chia-Yang Lin and
• Tsuyoshi Michinobu

Beilstein J. Nanotechnol. 2023, 14, 454–466, doi:10.3762/bjnano.14.36

• depends on the number of layers, which was caused by the surface structure of the multilayer PPy nanosheets. The high roughness and sharp local curvature of the multilayer PPy nanosheets were retained and incident light was effectively redistributed. In other words, transmitted light is confined in the

Liquid phase exfoliation of talc: effect of the medium on flake size and shape

• Samuel M. Sousa,
• Helane L. O. Morais,
• Joyce C. C. Santos,
• Ana Paula M. Barboza,
• Bernardo R. A. Neves,
• Elisângela S. Pinto and
• Mariana C. Prado

Beilstein J. Nanotechnol. 2023, 14, 68–78, doi:10.3762/bjnano.14.8

• substrate appears in black to dark blue. Following previous works, we consider flakes with ten or less layers as “few-layer” [25]. Since talc has a layer thickness of approximately 1 nm [12], we did not convert the height to the number of layers as it is a direct conversion. Few-layer flakes appear in light

• offer a comparison of the characteristics of the sample. The samples differ more in thickness-related parameters (thus, the number of layers) than in the lateral size-related parameters. To further compare shape-related features of the samples, we plotted topological vectors of pairwise ratios among

• butanone. The exfoliation medium has an influence on flake size and shape and should be chosen according to the desired application. Implications go beyond the mean number of layers of the flakes (all four media yielded few-layer-rich solutions). Flake size (variance and asymmetry of distribution), few

A nonenzymatic reduced graphene oxide-based nanosensor for parathion

• Sarani Sen,
• Anurag Roy,
• Ambarish Sanyal and
• Parukuttyamma Sujatha Devi

Beilstein J. Nanotechnol. 2022, 13, 730–744, doi:10.3762/bjnano.13.65

• depend on the number of layers and the distance between the layers, which can be changed by a variation of the synthesis protocol to achieve a higher electroactive surface area and electrical conductivity. Figure 4A displays a higher oxidation/reduction peak current of Fe2+/3+ redox couple for the

Reliable fabrication of transparent conducting films by cascade centrifugation and Langmuir–Blodgett deposition of electrochemically exfoliated graphene

• Teodora Vićentić,
• Stevan Andrić,
• Vladimir Rajić and
• Marko Spasenović

Beilstein J. Nanotechnol. 2022, 13, 666–674, doi:10.3762/bjnano.13.58

• the substrate completely. To analyze the electrical properties of the synthesized graphene films, resistance values of each film were measured. Resistance values, optical transparency values, and the average number of layers in each graphene film are shown in Table 2. A larger number of graphene

• scattering centers from dark-field observation. Both the number of particles and their total area decreases with centrifugation rate. Measured optical transparency, number of layers, and electrical resistance for samples obtained at different centrifugation rates, dissolved in the specified volumes of NMP

Electrostatic pull-in application in flexible devices: A review

• Teng Cai,
• Yuming Fang,
• Yingli Fang,
• Ruozhou Li,
• Ying Yu and
• Mingyang Huang

Beilstein J. Nanotechnol. 2022, 13, 390–403, doi:10.3762/bjnano.13.32

• common electrode materials are GR-Au and GR-GR. By adjusting the size of the graphene sheets, the number of layers and the gap, different pull-in voltages can be obtained. GR-Au: A typical GR-Au structure is shown in Figure 3a. As the structure requires a sacrificial layer to keep GR suspended and avoid

Comprehensive review on ultrasound-responsive theranostic nanomaterials: mechanisms, structures and medical applications

• Sepand Tehrani Fateh,
• Lida Moradi,
• Elmira Kohan,
• Michael R. Hamblin and
• Amin Shiralizadeh Dezfuli

Beilstein J. Nanotechnol. 2021, 12, 808–862, doi:10.3762/bjnano.12.64

Influence of electrospray deposition on C₆₀ molecular assemblies

• Antoine Hinaut,
• Sebastian Scherb,
• Sara Freund,
• Zhao Liu,
• Thilo Glatzel and
• Ernst Meyer

Beilstein J. Nanotechnol. 2021, 12, 552–558, doi:10.3762/bjnano.12.45

• cluster of Figure 3d. The number of layers ranges from one to at least five. Moreover, the islands present a more rounded shape, compared to TE islands, and no direction favored by the sixfold symmetry is observed. The influence of HV-ESD on the surface itself can also be seen. First, monolayer-deep pits

Mapping the local dielectric constant of a biological nanostructured system

• Wescley Walison Valeriano,
• Rodrigo Ribeiro Andrade,
• Juan Pablo Vasco,
• Angelo Malachias,
• Bernardo Ruegger Almeida Neves,
• Paulo Sergio Soares Guimarães and
• Wagner Nunes Rodrigues

Beilstein J. Nanotechnol. 2021, 12, 139–150, doi:10.3762/bjnano.12.11

• regions are the thickness and the number of layers. Each multilayered structure is wrapped by a wax layer, which is the irregular region at the boundary of the wings in the maps of Figure 6, and as a valley in the relative permittivity profile with εr(wax) ≈ 4 in Figure 7. Using time-of-flight secondary

• addition, the number of layers and their thickness varies from one color region to the other. Comparing the composition of the layers measured in the TOF-SIMS study [18] with the relative permittivity maps of this work, we can say that melanin-rich layers have a relative permittivity of 8 ± 1, while low

• obtained via EFM with the photonic behavior of the wing. The wing has several layers with thicknesses comparable to the wavelengths of visible light. Through refraction and diffraction, which depend on the thicknesses, refractive index, and the number of layers, light of certain wavelengths is reflected

Nanomechanics of few-layer materials: do individual layers slide upon folding?

• Ronaldo J. C. Batista,
• Rafael F. Dias,
• Ana P. M. Barboza,
• Alan B. de Oliveira,
• Taise M. Manhabosco,
• Thiago R. Gomes-Silva,
• Matheus J. S. Matos,
• Andreij C. Gadelha,
• Cassiano Rabelo,
• Luiz G. L. Cançado,
• Ado Jorio,
• Hélio Chacham and
• Bernardo R. A. Neves

Beilstein J. Nanotechnol. 2020, 11, 1801–1808, doi:10.3762/bjnano.11.162

• mechanical properties of folded edges, which allows for the experimental determination of the bending stiffness (κ) of multilayered 2D materials as a function of the number of layers (n). In the case of talc, we obtain κ ∝ n3 for n ≥ 5, indicating no interlayer sliding upon folding, at least in this

• carbon nanotubes [13][14]. The interlayer slip is also intimately related to the dependence of κ on the thickness or the number of layers of a 2D material, which, in the case of very thin 2D materials, may be very different from that obtained from classical theories [12]. The quantification and

• number of layers [34]. In this work, we present a method to obtain interlayer and 2D material/substrate adhesion energies and the bending stiffness of 2D materials by experimentally probing the mechanical response of folded edges to deformation. A folded edge is defined as an edge region of the 2D

Light–matter interactions in two-dimensional layered WSe₂ for gauging evolution of phonon dynamics

• Avra S. Bandyopadhyay,
• Chandan Biswas and
• Anupama B. Kaul

Beilstein J. Nanotechnol. 2020, 11, 782–797, doi:10.3762/bjnano.11.63

• oscillator model to explain the damping mechanism in WSe2. From this it was determined that the damping coefficient increases with the number of layers. The work reported here sheds fundamental insights into the evolution of phonon dynamics in WSe2 and should help pave the way for designing high-performance

• times larger compared to the red-shift ≈ 0.47 cm−1 when the sample thickness increased from 1L to bulk. Another important observation from Figure 1e is the increase in intensity of the A1g peak as the number of layers increases, which is likely due to positive reinforcement arising from interference

• found from the data in Figure 1e that the Δω was 7.5 cm−1, 8.4 cm−1 and 9.1 cm−1 for 1L, ML and bulk WSe2, respectively. Thus, the Raman peaks exhibit a larger separation as thickness increases. Monolayer WSe2 undergoes a transition from direct to indirect bandgap (Eg) as the number of layers increases

Multilayer capsules made of weak polyelectrolytes: a review on the preparation, functionalization and applications in drug delivery

• Varsha Sharma and
• Anandhakumar Sundaramurthy

Beilstein J. Nanotechnol. 2020, 11, 508–532, doi:10.3762/bjnano.11.41

• varying the size of the sacrificial template [10]. The shell thickness can also be altered by the number of layers and the preparation conditions, thus providing control over thickness and morphology. Notably, these capsules have better encapsulation efficiency (EE) and a stable zeta potential mainly due

An advanced structural characterization of templated meso-macroporous carbon monoliths by small- and wide-angle scattering techniques

• Felix M. Badaczewski,
• Marc O. Loeh,
• Torben Pfaff,
• Dirk Wallacher,
• Daniel Clemens and
• Bernd M. Smarsly

Beilstein J. Nanotechnol. 2020, 11, 310–322, doi:10.3762/bjnano.11.23

• carbon materials. The disorder-induced D band arises from breathing vibrations of carbon rings and the G band resulting from carbon-chain vibrations prove the sp2-hybridized turbostratic microstructure. The G′ band is an overtone, where two phonons are involved. It scales with the number of layers in a

Synthesis and characterization of quaternary La(Sr)S–TaS₂ misfit-layered nanotubes

• Marco Serra,
• Erumpukuthickal Ashokkumar Anumol,
• Dalit Stolovas,
• Iddo Pinkas,
• Ernesto Joselevich,
• Reshef Tenne,
• Andrey Enyashin and
• Francis Leonard Deepak

Beilstein J. Nanotechnol. 2019, 10, 1112–1124, doi:10.3762/bjnano.10.111

• assigned to the A1g vibration of the 2H-TaS2. Obviously, the diameter, number of layers and chirality varies from one nanotube to the next, and from one batch to the next. This polydispersity leads to the broadening of the peaks and minor shifts in their positions. Increasing the Sr content in the lattice

Direct growth of few-layer graphene on AlN-based resonators for high-sensitivity gravimetric biosensors

• Jimena Olivares,
• Teona Mirea,
• Lorena Gordillo-Dagallier,
• Bruno Marco,
• José Miguel Escolano,
• Marta Clement and
• Enrique Iborra

Beilstein J. Nanotechnol. 2019, 10, 975–984, doi:10.3762/bjnano.10.98

• stage, carbon atoms segregated from the Ni film to form the graphene layer on its surface. The cooling rate was critical because the graphene film maintains a quasi-equilibrium with the atmosphere and the carbon inside the Ni film. The number of layers of the resulting graphene depended on the cooling

Direct observation of the CVD growth of monolayer MoS₂ using in situ optical spectroscopy

• Claudia Beatriz López-Posadas,
• Yaxu Wei,
• Wanfu Shen,
• Daniel Kahr,
• Michael Hohage and
• Lidong Sun

Beilstein J. Nanotechnol. 2019, 10, 557–564, doi:10.3762/bjnano.10.57

• , each type of 2D TMDC material possesses specific optical properties which are characteristic of their chemical composition, crystalline structure, and number of layers [2][20]. Their optical properties are also sensitive to extrinsic modifications, for instance, interaction with substrate [21], gas

A novel polyhedral oligomeric silsesquioxane-modified layered double hydroxide: preparation, characterization and properties

• Xianwei Zhang,
• Zhongzhu Ma,
• Hong Fan,
• Carla Bittencourt,
• Jintao Wan and
• Philippe Dubois

Beilstein J. Nanotechnol. 2018, 9, 3053–3068, doi:10.3762/bjnano.9.284

• totally removed and no unmodified LDH phase is formed. This shows that OCPS anions can be efficiently intercalated within the LDH layers using the one-step method. The crystallite size and the average number of layers estimated from crystallite size and interlayer distance are plotted in Figure 6b

• . Compared to unmodified LDH, OLDH has a smaller crystallite size and shows a nearly two-fold reduction of the average number of layers. This drastic reduction could be explained as follows: With the interlayer spacing being increased by OCPS molecules, a large-size stacking of LDH laminae is sterically

• and prepared via a one-step route. The structure and micromorphology of OLDH were confirmed by FTIR, XPS, XRD, TEM, SEM and elemental analysis. Results showed that OLDH exhibited an increased interlayer distance of 1.33 nm, a nearly two-fold reduction in the average number of layers compared to

Two-dimensional semiconductors pave the way towards dopant-based quantum computing

• José Carlos Abadillo-Uriel,
• Belita Koiller and
• María José Calderón

Beilstein J. Nanotechnol. 2018, 9, 2668–2673, doi:10.3762/bjnano.9.249

• ]. Some gaps are also known experimentally from transport and optical measurements [21][22][23]. The size and nature (direct or indirect) of the gap depends on the number of layers [29], the distance between them [28], and the nature of the substrate or atomic reconstructions [30]. Properties of these

• should reduce the technological demands on donor positioning. Conclusion The variability of binding energies as a function of the chemical composition, substrate and number of layers, opens up a wide range of possibilities for the potential use of 2D materials to host donors where electrons may serve as

Recent highlights in nanoscale and mesoscale friction

• Andrea Vanossi,
• Dirk Dietzel,
• Andre Schirmeisen,
• Ernst Meyer,
• Rémy Pawlak,
• Thilo Glatzel,
• Marcin Kisiel,
• Shigeki Kawai and
• Nicola Manini

Beilstein J. Nanotechnol. 2018, 9, 1995–2014, doi:10.3762/bjnano.9.190

• friction was recently observed for micro- and macroscale systems based on incommensurate sliding between graphene-covered spheres or “nanoscrolls” and substrates [76][77]. Also a decrease of friction shear stress with increasing number of layers has been observed for graphene over Si/SiO2 in vacuum

• phenomenon under load [118]. Simulations [119] agree with experiment that friction depends sensitively on the number or residual confined layers in the interface. At a given number of layers, friction shows a relatively modest increase with load. A systematic investigation of friction as a function of load

Toward the use of CVD-grown MoS₂ nanosheets as field-emission source

• Geetanjali Deokar,
• Nitul S. Rajput,
• Junjie Li,
• Francis Leonard Deepak,
• Wei Ou-Yang,
• Nicolas Reckinger,
• Carla Bittencourt,
• Jean-Francois Colomer and
• Mustapha Jouiad

Beilstein J. Nanotechnol. 2018, 9, 1686–1694, doi:10.3762/bjnano.9.160

• ][16] and the number of layers [16]. Various methods have been used to synthesize vertically aligned MoS2 NSs: liquid-phase exfoliation [17], hydrothermal synthesis [8] or chemical vapor deposition (CVD) [15][17][18]. CVD is regarded as the most promising method to synthesize high-quality MoS2 with

• of MoS2 polycrystals. A high-resolution (HR) TEM image is shown in Figure 3b. The stacking periodicity (the interlayer distance) is found to be around 0.63 nm. The number of layers in a NS is found in the range of 15–20. One should note that the NS thickness cannot be solely determined by plane-view

A simple extension of the commonly used fitting equation for oscillatory structural forces in case of silica nanoparticle suspensions

• Sebastian Schön and
• Regine von Klitzing

Beilstein J. Nanotechnol. 2018, 9, 1095–1107, doi:10.3762/bjnano.9.101

• molecules, compared to the bulk. The degree of ordering decreases exponentially with increasing distance from the wall, levelling off to bulk distribution. This region of oscillating density, also called the interfacial region, encompasses only a small number of layers. The thickness of the interfacial

An implementation of spin–orbit coupling for band structure calculations with Gaussian basis sets: Two-dimensional topological crystals of Sb and Bi

• Sahar Pakdel,
• Mahdi Pourfath and
• J. J. Palacios

Beilstein J. Nanotechnol. 2018, 9, 1015–1023, doi:10.3762/bjnano.9.94

• transitions and give the most faithful representation of the electronic band structure for any number of layers. This includes the presence of helical and topologically protected edge or surface states. For comparison, and as a reliable reference, we make use of the band structures obtained from the well

Graphene composites with dental and biomedical applicability

• Sharali Malik,
• Felicite M. Ruddock,
• Adam H. Dowling,
• Kevin Byrne,
• Wolfgang Schmitt,
• Ivan Khalakhan,
• Yoshihiro Nemoto,
• Hongxuan Guo,
• Lok Kumar Shrestha,
• Katsuhiko Ariga and
• Jonathan P. Hill

Beilstein J. Nanotechnol. 2018, 9, 801–808, doi:10.3762/bjnano.9.73

• 08.10.2012). The shape and position of the Raman 2D band (≈2700 cm−1) provides a useful analysis for assessing the quality and number of layers in graphene materials [14][15]. As the FLG material is composed of “flakes” the edges of the flakes give rise to a D band. The shape and position of the 2D band in