Size-dependent Raman shift of semiconductor nanomaterials determined using bond number and strength

2017 ◽  
Vol 19 (41) ◽  
pp. 28056-28062 ◽  
Author(s):  
H. Li ◽  
X. W. He ◽  
H. J. Xiao ◽  
H. N. Du ◽  
J. Wang ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Bond Number ◽  
Raman Shift ◽  
Size Dependent ◽  
Semiconductor Nanomaterials

Significant variations in Raman shifts with decreasing material size,D, have been detected in Raman spectroscopy.

Application of the G'/D Raman Ratio for Purity Assessment of Multi-Walled Carbon Nanotubes

2007 ◽  
Vol 1018 ◽  
Author(s):  
Roberta DiLeo ◽  
Brian Landi ◽  
Ryne Raffaelle
Keyword(s):  
Carbon Nanotubes ◽  
Raman Spectroscopy ◽  
Excitation Energy ◽  
Double Resonance ◽  
Raman Shift ◽  
Resonance Theory ◽  
Sem Images ◽  
Purity Assessment ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

AbstractCarbonaceous purity assessment methods are being sought after for all types of carbon nanotubes as a means to standardize the material metrology. Our most recent work has evaluated chemical vapor synthesized multi-walled carbon nanotubes (MWNTs). This effort included a protocol for assessment involving qualitative information from scanning electron microscopy (SEM) images and quantitative information from thermogravimetric analysis (TGA) and Raman spectroscopy. Presently, the analysis using Raman spectroscopy on a constructed sample set has been extended to a second excitation energy (HeNe laser at 1.96 eV) and the similar trends in the relative Raman peak ratios have been measured. In contrast to the G-band, the D and G' peaks demonstrate a Raman shift that is excitation energy-dependent, consistent with the double resonance theory. However, the Raman ratio of IG'/ID is independent of excitation energy and is observed to be the most sensitive to MWNT carbonaceous purity. Application of this approach to MWNT arrays grown on SiO2 is compared to conventional bulk powders synthesized under similar conditions. The MWNT arrays show a high degree of vertical alignment based upon SEM and a measured carbonaceous purity using the IG'/ID ratio of 75% w/w.

Size Dependent Bond Length of Metallic Clusters by Considering Bond Number

2016 ◽  
Vol 850 ◽  
pp. 314-318
Author(s):  
Hui Li ◽  
Hao Jie Xiao ◽  
Jiang Wang ◽  
Hai Xia Zhang ◽  
Hai Cheng Xuan ◽  
...  
Keyword(s):  
Bond Length ◽  
Bond Number ◽  
Single Bond ◽  
Metallic Clusters ◽  
Structure Relaxation ◽  
Atomic Structures ◽  
Size Dependent ◽  
Model Free ◽  
Theoretical Predictions ◽  
Ag Clusters

In this study, size-dependent bond length of metallic clusters is established by introducing bond number. This model, free of any adjustable parameters, can be utilized to predict the change rule of bond length with size. If the atomic structure of a cluster is known, the size and shape-dependent bond number are obtained. The cubooctahedral structure is taken for simplicity to describe the shape and geometric characteristics of metallic clusters. It is found that the bond length decreases with the decreased size of metallic clusters, which is due to the structure relaxation and enhanced single bond energy. The theoretical predictions are consistent with the evidences of the simulations for Au and Ag clusters. This confirms the validity of taking cubooctahedron structure, even if the simulated Au and Ag clusters are not cuboctahedron ones. This can be expected to other metallic clusters even with other atomic structures.

scholarly journals Rapid Detection and Quantification of Plant Innate Immunity Response Using Raman Spectroscopy

2021 ◽  
Vol 12 ◽  
Author(s):  
Pil Joong Chung ◽  
Gajendra P. Singh ◽  
Chung-Hao Huang ◽  
Sayuj Koyyappurath ◽  
Jun Sung Seo ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Innate Immunity ◽  
Quantitative Measure ◽  
Raman Shift ◽  
Regulatory Mutants ◽  
Response Index ◽  
Spectral Bands ◽  
Elicitor Response ◽  
Raman Spectral ◽  
Detection And Quantification

We have developed a rapid Raman spectroscopy-based method for the detection and quantification of early innate immunity responses in Arabidopsis and Choy Sum plants. Arabidopsis plants challenged with flg22 and elf18 elicitors could be differentiated from mock-treated plants by their Raman spectral fingerprints. From the difference Raman spectrum and the value of p at each Raman shift, we derived the Elicitor Response Index (ERI) as a quantitative measure of the response whereby a higher ERI value indicates a more significant elicitor-induced immune response. Among various Raman spectral bands contributing toward the ERI value, the most significant changes were observed in those associated with carotenoids and proteins. To validate these results, we investigated several characterized Arabidopsis pattern-triggered immunity (PTI) mutants. Compared to wild type (WT), positive regulatory mutants had ERI values close to zero, whereas negative regulatory mutants at early time points had higher ERI values. Similar to elicitor treatments, we derived an analogous Infection Response Index (IRI) as a quantitative measure to detect the early PTI response in Arabidopsis and Choy Sum plants infected with bacterial pathogens. The Raman spectral bands contributing toward a high IRI value were largely identical to the ERI Raman spectral bands. Raman spectroscopy is a convenient tool for rapid screening for Arabidopsis PTI mutants and may be suitable for the noninvasive and early diagnosis of pathogen-infected crop plants.

scholarly journals Microstructural analysis of nitrogen-doped char by Raman spectroscopy: Raman shift analysis from first principles

Carbon ◽  
2020 ◽  
Vol 167 ◽  
pp. 559-574
Author(s):  
Michael Ayiania ◽  
Elsa Weiss-Hortala ◽  
Matthew Smith ◽  
Jean-Sabin McEwen ◽  
Manuel Garcia-Perez
Keyword(s):  
Raman Spectroscopy ◽  
First Principles ◽  
Microstructural Analysis ◽  
Raman Shift ◽  
Nitrogen Doped ◽  
Shift Analysis

Blue-emitting and self-assembled thinner perovskite CsPbBr3 nanoplates: synthesis and formation mechanism

Nanoscale ◽  
2020 ◽  
Vol 12 (16) ◽  
pp. 9231-9239 ◽  
Author(s):  
Xiaolin Xiao ◽  
Ye Li ◽  
Rong-Jun Xie
Keyword(s):  
Formation Mechanism ◽  
Optoelectronic Properties ◽  
Great Promise ◽  
Size Dependent ◽  
Semiconductor Nanomaterials ◽  
Self Assembled ◽  
Low Dimensional

Low dimensional semiconductor nanomaterials show great promise for a variety of applications due to their size-dependent and excellent optoelectronic properties.

scholarly journals DNA sequencing by synthesis using 3′-O-azidomethyl nucleotide reversible terminators and surface-enhanced Raman spectroscopic detection

RSC Advances ◽  
2014 ◽  
Vol 4 (90) ◽  
pp. 49342-49346 ◽  
Author(s):  
Mirkó Palla ◽  
Wenjing Guo ◽  
Shundi Shi ◽  
Zengmin Li ◽  
Jian Wu ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Dna Sequencing ◽  
Surface Enhanced Raman Spectroscopy ◽  
Raman Shift ◽  
Azido Group ◽  
Raman Spectroscopic ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Sequencing By Synthesis

DNA sequencing using surface enhanced Raman spectroscopy for the detection of the unique Raman shift of the azido group was demonstrated using 3′-O-azidomethyl nucleotide reversible terminators in polymerase reaction.

scholarly journals PROBING INTERNAL STRESS AND CRYSTALLINITY IN WET FOAM VIA RAMAN SPECTROSCOPY

2009 ◽  
Vol 23 (19) ◽  
pp. 3913-3924
Author(s):  
T. K. BARIK ◽  
P. BANDYOPADHYAY ◽  
A. ROY
Keyword(s):  
Raman Spectroscopy ◽  
Internal Stress ◽  
Vibrational Mode ◽  
Low Frequency ◽  
Time Frame ◽  
Raman Shift ◽  
Specific Time ◽  
Time Intervals ◽  
Microscope Images ◽  
Average Size

In this paper, we correlate the internal stress and the characteristics of a vibrational mode in wet foam. Using microscope images, we estimate the average size of the bubbles in wet foam, at specific time intervals, over a duration of 24 h. Raman spectra are also recorded at the same time intervals, over the same time frame. We show that the internal stress, originated from the microscopic structural change of foam with aging, can be related to the observed Raman shift of the low-frequency methylene rocking mode of the constituent surfactant molecules in foam. In this paper, we also show the capability of the Raman spectroscopy to reveal the crystallinity in foamy materials, when studied for a longer period of time.

scholarly journals Detection and Aggregation of Listeria Monocytogenes Using Polyclonal Antibody Gold-Coated Magnetic Nanoshells Surface-Enhanced Raman Spectroscopy Substrates

2021 ◽  
Vol 3 ◽  
Author(s):  
Robert T. Busch ◽  
Farzia Karim ◽  
Yvonne Sun ◽  
H. Christopher Fry ◽  
Yuzi Liu ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Listeria Monocytogenes ◽  
Polyclonal Antibody ◽  
Surface Enhanced Raman Spectroscopy ◽  
Raman Shift ◽  
Label Free ◽  
Surface Binding ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Induced Aggregation

Magnetic nanoshells with tailored surface chemistry can enhance bacterial detection and separation technologies. This work demonstrated a simple technique to detect, capture, and aggregate bacteria with the aid of end-functionalized polyclonal antibody gold-coated magnetic nanoshells (pAb-Lis-AuMNs) as surface-enhanced Raman spectroscopy (SERS) probes. Listeria monocytogenes were used as the pathogenic bacteria and the pAb-Lis-AuMNs, 300 nm diameter, were used as probes allowing facile magnetic separation and aggregation. An optimized covalent bioconjugation procedure between the magnetic nanoshells and the polyclonal antibody was performed at pH six via a carbodiimide crosslinking reaction. Spectroscopic and morphological characterization techniques confirmed the fabrication of stable pAb-Lis-AuMNs. The resulting pAb-Lis-AuMNs acted as a SERS probe for L. monocytogenes based on the targeted capture via surface binding interactions and magnetically induced aggregation. Label-free SERS measurements were recorded for the minimum detectable amount of L. monocytogenes based on the SERS intensity at the 1388 cm−1 Raman shift. L. monocytogenes concentrations exhibited detection limits in the range of 104–107 CFU ml−1, before and after aggregation. By fitting these concentrations, the limit of detection of this method was ∼103 CFU ml−1. Using a low-intensity magnetic field of 35 G, pAb-Lis-AuMNs aggregated L. monocytogenes as demonstrated with microscopy techniques, including SEM and optical microscopy. Overall, this work presents a label-free SERS probe method comprised of a surface-modified polyclonal antibody sub-micron magnetic nanoshell structures with high sensitivity and magnetic induced separation that could lead to the fabrication of multiple single-step sensors.

Raman spectroscopy studies in InGaN/GaN wurtzite epitaxial films

2000 ◽  
Vol 639 ◽  
Author(s):  
Maria R. Correia ◽  
Sérgio Pereira ◽  
Teresa Monteiro ◽  
Estela Pereira ◽  
Eduardo Alves
Keyword(s):  
Raman Spectroscopy ◽  
Rutherford Backscattering Spectrometry ◽  
Indium Content ◽  
Epitaxial Films ◽  
Raman Shift ◽  
X Ray Diffraction ◽  
Lattice Constants ◽  
Sapphire Substrates ◽  
Vegard’S Law ◽  
Spectroscopy Studies

ABSTRACTIn this work we studied a set of nominally undoped epitaxial InxGa1−xN wurtzite films grown on (0001) sapphire substrates. In order to separate the contribution of the strain and indium content in the phonon mode frequency, indium mole fraction was determined using a strain insensitive method, Rutherford backscattering spectrometry (RBS). Strain was evaluated by comparing the lattice constants measured by X-ray diffraction (XRD) with the relaxed lattice parameters given by Vegard's law. Samples with comparable indium content, but under different states of strain were used as reference. This allowed the behaviour of different Raman shift modes for both, strain and composition to be independently established. We also assess the potentiality of Raman spectroscopy for the evaluation of crystalline quality by comparing the results obtained with the ones provided by other well-established methods such as XRD and RBS.

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