Raman spectroscopy for CVD monolayer graphene: Fermi levels depending on different substrates material

2016 ◽  
Author(s):  
Solveyga E. Azbite ◽  
Alaudi K. Denisultanov ◽  
Mikhail K. Khodzitsky
Keyword(s):  
Raman Spectroscopy ◽  
Monolayer Graphene

Simple and environment-friendly method for graphene synthesis by using ultrasound.

2021 ◽  
Vol 17 ◽  
Author(s):  
Irena Markovska ◽  
Dimitar Georgiev ◽  
Fila Yovkova ◽  
Miroslav Abrashev
Keyword(s):  
Electrical Conductivity ◽  
Raman Spectroscopy ◽  
Monolayer Graphene ◽  
Conductivity Measurements ◽  
Environment Friendly ◽  
Complex Processes ◽  
Graphene Synthesis ◽  
Pure Graphite ◽  
Ft Ir ◽  
Electrodes For Supercapacitors

Background: This paper proposes a technology for the production of monolayer graphene by an easy, accessible, and non-toxic method. Methods: For the preparation of graphene, a combination of chemical and physical (ultrasonic) treatment of the original graphite precursor (purity >99%) was applied. The precursor of graphite is placed in a beaker with a solution of KOH or H2SO4. The mixtures were homogenized well and sonicated for 4h. The applied ultrasound has a power of 120 W, frequency 40 kHz. Due to the effects of ultrasound, complex processes take place in the solutions, which leads to the formation of superfine graphene. Better results were obtained at samples treated with 2n H2SO4. The physicochemical properties of the resulting graphene were characterized mainly by Raman spectroscopy, FT-IR, TEM, SEM, and electrical conductivity measurements. Results: Our research was focused mainly on the field of nanotechnology, in particular on the synthesis of graphene, which could be used as a coating on electrodes for supercapacitors. In this connection, three series of samples were developed in which the pristine graphite was treated with 2n H2SO4, 4n H2SO4, and 6n H2SO4, respectively, and their electrical properties were measured. Conclusion: The obtained graphene shows electrical resistivity 2-3 times lower than that of the precursor of pure graphite.

scholarly journals The strength of mechanically-exfoliated monolayer graphene deformed on a rigid polymer substrate

Nanoscale ◽  
2019 ◽  
Vol 11 (30) ◽  
pp. 14339-14353 ◽  
Author(s):  
Xin Zhao ◽  
Dimitrios G. Papageorgiou ◽  
Liyan Zhu ◽  
Feng Ding ◽  
Robert J. Young
Keyword(s):  
Raman Spectroscopy ◽  
Systematic Investigation ◽  
Polymer Substrate ◽  
Monolayer Graphene ◽  
Rigid Polymer

A systematic investigation of the strength of monolayer graphene via the application of Raman spectroscopy is presented, revealing that the strength of the flakes decreases with increasing flake width, due to the presence of defects.

Graphene Layers on Silicon Carbide Studied by Raman Spectroscopy

2008 ◽  
Vol 600-603 ◽  
pp. 567-570 ◽  
Author(s):  
Jonas Röhrl ◽  
Martin Hundhausen ◽  
Konstantin V. Emtsev ◽  
Thomas Seyller ◽  
Lothar Ley
Keyword(s):  
Silicon Carbide ◽  
Raman Spectroscopy ◽  
Light Scattering ◽  
Graphene Layer ◽  
Monolayer Graphene ◽  
Spectroscopy Study ◽  
Graphene Layers ◽  
Layer Graphene ◽  
Micro Raman Spectroscopy ◽  
Few Layer Graphene

We present a micro-Raman spectroscopy study on single- and few layer graphene (FLG) grown on the silicon terminated surface of 6H-silicon carbide (SiC). On the basis of the 2D-line (light scattering from two phonons close to the K-point in the Brillouin zone) we distinguish graphene mono- from bilayers or few layer graphene. Monolayers have a 2D-line consisting of only one component, whereas more than one component is observed for thicker graphene layers. Compared to the graphite the monolayer graphene lines are shifted to higher frequencies. We tentatively ascribe the corresponding phonon hardening to strain in the first graphene layer.

Monolayer graphene films through nickel catalyzed transformation of fullerol and graphene quantum dots: a Raman spectroscopy study

2014 ◽  
Vol T162 ◽  
pp. 014030 ◽  
Author(s):  
J R Prekodravac ◽  
S P Jovanović ◽  
I D Holclajtner-Antunović ◽  
D B Peruško ◽  
V B Pavlović ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Raman Spectroscopy ◽  
Graphene Quantum Dots ◽  
Monolayer Graphene ◽  
Spectroscopy Study ◽  
Graphene Films

scholarly journals Rapid Biomarker Screening of Alzheimer's Disease by Machine Learning and Graphene-Assisted Raman Spectroscopy

2021 ◽  
Author(s):  
Ziyang Wang ◽  
Jiarong Ye ◽  
Li Ding ◽  
Tomotaroh Granzier-Nakajima ◽  
Shubhang Sharma ◽  
...  
Keyword(s):  
Machine Learning ◽  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Raman Spectroscopy ◽  
Brain Slices ◽  
Rapid Screening ◽  
Monolayer Graphene ◽  
Accurate Identification ◽  
Machine Learning Classification ◽  
The Brain

As the most common cause of dementia, Alzheimer's disease (AD) faces challenges in terms of understanding of pathogenesis, developing early diagnosis and developing effective treatment. Rapid and accurate identification of AD biomarkers in the brain will be critical to provide novel insights of AD. To this end, in the current work, we developed a system that can enable a rapid screening of AD biomarkers by employing Raman spectroscopy and machine learning analyses in AD transgenic animal brains. Specifically, we collected Raman spectra on slices of mouse brains with and without AD, and used machine learning to classify AD and non-AD spectra. By contacting monolayer graphene with the brain slices, we achieved significantly increased accuracy from 77% to 98% in machine learning classification. Further, we identified the Raman signature bands that are most important in classifying AD and non-AD samples. Based on these, we managed to identify AD-related biomolecules, which have been confirmed by biochemical studies. Our Raman-machine learning integrated method is promising to greatly accelerate the study of AD and can be potentially extended to human samples and various other diseases.

Probing the structural transition from buffer layer to quasifreestanding monolayer graphene by Raman spectroscopy

2019 ◽  
Vol 99 (4) ◽  
Author(s):  
S. Wundrack ◽  
D. Momeni Pakdehi ◽  
P. Schädlich ◽  
F. Speck ◽  
K. Pierz ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Buffer Layer ◽  
Structural Transition ◽  
Monolayer Graphene

scholarly journals Visualization of subnanometric phonon modes in a plasmonic nano-cavity via ambient tip-enhanced Raman spectroscopy

2019 ◽  
Vol 3 (1) ◽  
Author(s):  
Maria Vanessa Balois ◽  
Norihiko Hayazawa ◽  
Satoshi Yasuda ◽  
Katsuyoshi Ikeda ◽  
Bo Yang ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Strain Analysis ◽  
Crystalline Lattice ◽  
Monolayer Graphene ◽  
Optical Phonons ◽  
Phonon Modes ◽  
Free Graphene ◽  
2D Nanomaterials ◽  
Tip Enhanced Raman Spectroscopy ◽  
Combination Mode

Abstract Phonons provide information on the physicochemical properties of a crystalline lattice from the material’s vibrational spectrum. Optical phonons, in particular, can be probed at both micrometre and nanometre scales using light-based techniques, such as, micro-Raman and tip-enhanced Raman spectroscopy (TERS), respectively. Selection rules, however, govern the accessibility of the phonons and, hence, the information that can be extracted about the sample. Herein, we simultaneously observe both allowed and forbidden optical phonon modes of defect-free areas in monolayer graphene to study nanometre scale strain variations and plasmonic activation of the Raman peaks, respectively, using our home-built TERS system in ambient. Through TERS imaging, strain variations and nanometre-sized domains down to 5 nm were visualised with a spatial resolution of 0.7 nm. Moreover, such subnanometric confinement was found to activate not only the D and D’ forbidden phonon modes but also their D + D’ combination mode. With our TERS in ambient system, the full phonon characterisation of defect-free graphene and other 2D nanomaterials is now possible, which will be useful for subnanometre strain analysis and exploring the inherent properties of defect-free materials.

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