Journal of Raman Spectroscopy最新文献

{"title":"Chemical Composition Dependent Raman Scattering Spectroscopy of MBE Grown Manganese - Based Bismuth Telluride Topological Insulator Thin Films","authors":"N. Kumar,&nbsp;Denis V. Ishchenko,&nbsp;Ilya A. Milekhin,&nbsp;Ekaterina D. Kyrova,&nbsp;Evgeny V. Fedosenko,&nbsp;Alexander G. Milekhin,&nbsp;Oleg E. Tereshchenko","doi":"10.1002/jrs.6779","DOIUrl":"https://doi.org/10.1002/jrs.6779","url":null,"abstract":"<div>\u0000 \u0000 <p>Chemical composition dependent vibrational modes of manganese-based bismuth telluride (MBT) magnetic topological insulators thin films grown by molecular beam epitaxy were studied by Raman spectroscopy and compared with the vibrational modes of Bi₂Te₃ films. Intensity of \u0000<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msubsup>\u0000 <mi>E</mi>\u0000 <mi>g</mi>\u0000 <mn>3</mn>\u0000 </msubsup>\u0000 </mrow>\u0000 <annotation>$$ {mathrm{E}}_g&amp;#x0005E;3 $$</annotation>\u0000 </semantics></math> TO mode was much stronger in Bi efficient MBT film. In contrast, vibrational cross-section of \u0000<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msubsup>\u0000 <mi>A</mi>\u0000 <mrow>\u0000 <mn>1</mn>\u0000 <mi>g</mi>\u0000 </mrow>\u0000 <mn>2</mn>\u0000 </msubsup>\u0000 </mrow>\u0000 <annotation>$$ {mathrm{A}}_{1g}&amp;#x0005E;2 $$</annotation>\u0000 </semantics></math> LO mode was stronger in Bi deficient MBT compound. \u0000<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msubsup>\u0000 <mi>E</mi>\u0000 <mi>g</mi>\u0000 <mn>3</mn>\u0000 </msubsup>\u0000 </mrow>\u0000 <annotation>$$ {mathrm{E}}_g&amp;#x0005E;3 $$</annotation>\u0000 </semantics></math> TO mode corresponds to in-plane vibrations of Bi-Te atomic layers. Deficiency of Bi atoms in the MBT indicated that the vibrational degree of freedom of Bi-Te in the septuple unit cell was less probable. Antisymmetric out-of-phase vibration of Te-Te atoms resulted in \u0000<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msubsup>\u0000 <mi>A</mi>\u0000 <mrow>\u0000 <mn>1</mn>\u0000 <mi>g</mi>\u0000 </mrow>\u0000 <mn>2</mn>\u0000 </msubsup>\u0000 </mrow>\u0000 <annotation>$$ {mathrm{A}}_{1g}&amp;#x0005E;2 $$</annotation>\u0000 </semantics></math> LO mode in which Bi atom was stationary, therefore vibrational cross-section of this mode for Bi deficient MBT film was stronger. A resonantly excited E_<i>g</i> and A_1<i>g</i> modes was observed at excitation energy 1.57 eV associated to deformation potential and Frohlich electron–phonon coupling, respectively.</p>\u0000 </div>","PeriodicalId":16926,"journal":{"name":"Journal of Raman Spectroscopy","volume":"56 5","pages":"409-419"},"PeriodicalIF":2.4,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143831443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Surface Enhanced Raman Spectral Monitoring of 50 KDa Filtrate Portions of Blood Serum Samples of Patients with Iron Deficiency Anemia","authors":"Rabia Tariq,&nbsp;Muhammad Zeshan Khalil,&nbsp;Haq Nawaz,&nbsp;Muhammad Irfan Majeed,&nbsp;Nosheen Rashid,&nbsp;Norah A. Albekairi,&nbsp;Abdulrahman Alshammari,&nbsp;Ali Kamran,&nbsp;Munawar Hussain,&nbsp;Seher Nawabzadi,&nbsp;Saima Afzal,&nbsp;Shanza Rauf,&nbsp;Eman Fatima,&nbsp;Muhammad Wasim","doi":"10.1002/jrs.6775","DOIUrl":"https://doi.org/10.1002/jrs.6775","url":null,"abstract":"<div>\u0000 \u0000 <p>Surface-enhanced Raman spectroscopy (SERS) is considered powerful analytical technique that significantly enhances the Raman scattering which enables the detection of low concentration of biomolecular analytes of blood serum, which can lead to early diagnosis of diseases. The aim of this study is Surface enhanced Raman spectral monitoring of 50 KDa filtrate portions of blood serum samples of patients with iron deficiency anemia. The blood serum components include higher molecular weight fractions (HMWF) and lower molecular weight fractions (LMWF) of biomolecules. The biomarkers of iron deficiency anemia, which are low molecular weight fractions are suppressed by high molecular weight fraction hence hindering them from contributing in the diagnosis of the disease. The ultra-filtration of the blood serum samples is performed using filtration devices of 50 KDa. The specific SERS spectral features related to biochemical markers of iron deficiency anemic subgroups (with different values of hemoglobin) from different blood serum samples are identified including 479, 535, 888, and 1300 cm⁻¹. These SERS features can be associated with different biomarkers of iron deficiency anemia consisting of ferritin, hepcidin, iron bound transferrin, and erythropoietin. Moreover, chemometric statistical techniques including principal component analysis (PCA) and partial least square regression (PLSR) are used for qualitative analysis of variations between spectral data and quantitative prediction of hemoglobin concentration of iron deficiency anemia samples, respectively.</p>\u0000 </div>","PeriodicalId":16926,"journal":{"name":"Journal of Raman Spectroscopy","volume":"56 5","pages":"369-380"},"PeriodicalIF":2.4,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143831388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Atomic Dynamics and Structural Transformations in Chalcedony as a Model Cryptocrystalline Multiphase System at Non-Ambient Conditions","authors":"Nicola Campomenosi,&nbsp;Mara Murri,&nbsp;Mauro Prencipe,&nbsp;Boriana Mihailova","doi":"10.1002/jrs.6780","DOIUrl":"https://doi.org/10.1002/jrs.6780","url":null,"abstract":"<p>The behaviour of chalcedony, a natural polycrystalline system consisting of cryptocrystalline (i.e., submicron-sized) quartz and moganite, has been investigated via in situ Raman spectroscopy under non-ambient conditions, complemented by hybrid Hartree–Fock/density-functional-theory (HF-DFT) simulations of moganite phonon modes at high pressure. The combined experimental and computational results clearly indicate that the peak neat 503 cm⁻¹ arises exclusively from the moganite SiO₄-ring mode rather than from OH librations of silanol groups. At high pressure and room temperature, the quartz fraction in chalcedony becomes metastable against coesite at 2.4 GPa and develops structural defects because of the anisotropic elastic strain arising from the interaction between cryptocrystalline moganite and quartz under the applied hydrostatic compressible stress. This process can trigger amorphization of quartz at pressures lower than those commonly observed in a quartz single crystal. At high temperature and ambient pressure, both quartz and moganite Raman peaks measured in chalcedony are excellent markers of both moganite and quartz <i>α-β</i> transformations. Further, we show that upon heating–cooling cycles of chalcedony, a part of the moganite fraction transforms into quartz, if the temperature of <i>α-β</i> quartz phase transition is crossed, confirming the overall metastability of the moganite structure with respect to that of <i>α</i> quartz. Moreover, the <i>α-β</i> moganite transition affects the rate of phonon softening on quartz on the approach to the phase-transition temperature. Our results demonstrate that the mutual impact of quartz and moganites is achieved via an admixture of phonons belonging to different phases but having the same symmetry and type of atomic vibrations, emphasizing the key role of Raman spectroscopy in studying structural transformations in multiphase systems.</p>","PeriodicalId":16926,"journal":{"name":"Journal of Raman Spectroscopy","volume":"56 5","pages":"420-434"},"PeriodicalIF":2.4,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jrs.6780","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143831389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of Lateral Resolutions Obtained by Different Methods for Confocal Raman Microscopes","authors":"Nobuyasu Itoh","doi":"10.1002/jrs.6781","DOIUrl":"https://doi.org/10.1002/jrs.6781","url":null,"abstract":"<p>Confocal Raman microscopes are widely used in various applications because they provide physical and chemical information at a submicron scale. A high lateral resolution in the confocal Raman microscope is essential for obtaining high-quality images. Although several methods have been proposed to evaluate the lateral resolution of Raman microscopes, it is unclear how comparable or different the evaluated results are depending on the methods and samples used. In this study, we examined the grating method using a chromium-coated patterned three-bar sample, the straight edge method using the edge of silicon and tungsten in NMIJ CRM 5207-a, and the narrow line method using carbon nanotubes and fluorescent particles. The lateral resolution evaluated by the patterned three-bar sample according to ISO 18516:2019 was ~0.7 μm and much worse than that obtained by the other methods (0.30 to 0.41 μm), which was mainly attributed to both the inherent property and structure of the patterned sample used in this study. Although the lateral resolution obtained by the other methods did not show a large difference, each method had advantages and disadvantages including the inherent properties and structures of the samples as well as optical effects. Thus, it is important to decide on the methods and samples depending on the purpose, and the selected methods and samples should include the results and measurement conditions.</p>","PeriodicalId":16926,"journal":{"name":"Journal of Raman Spectroscopy","volume":"56 5","pages":"389-397"},"PeriodicalIF":2.4,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jrs.6781","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143831057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Raman Spectroscopic Analysis of Cyanobacteria in Apatite-Containing Rocks of the Tomtor Nb-REE Deposit (Russia)","authors":"Tatyana N. Moroz,&nbsp;Howell G. M. Edwards,&nbsp;Sergey M. Zhmodik,&nbsp;Viktor A. Ponomarchuk,&nbsp;Sergey V. Goryainov","doi":"10.1002/jrs.6777","DOIUrl":"https://doi.org/10.1002/jrs.6777","url":null,"abstract":"<div>\u0000 \u0000 <p>Micro-Raman spectroscopy was employed to analyze apatite-containing samples from the Tomtor complex of ultrabasic rocks and carbonatites, located in the sharply continental region of Yakutia, Russia. Raman spectra excited at a wavelength of 532 nm revealed the characteristic vibrational bands of apatite, as well as bands attributed to carotenoid-type cyanobacteria. Additionally, as an artifact, the spectra exhibited bands resulting from the laser-induced photoluminescence of trivalent rare earth elements (REEs). Preresonance Raman spectra recorded at least two distinct C=C stretching modes of the β-carotene polyene chain, indicating the presence of this carotenoid component associated with apatite. Furthermore, three characteristic carotenoid bands were recorded in samples from the specific weathering crust on carbonatites that lacked apatite-related bands. These findings provide direct evidence of cyanobacteria in the studied samples, suggesting the likely involvement of microorganisms in the formation of Nb-REE-rich ores within the Tomtor field in Russia.</p>\u0000 </div>","PeriodicalId":16926,"journal":{"name":"Journal of Raman Spectroscopy","volume":"56 4","pages":"345-352"},"PeriodicalIF":2.4,"publicationDate":"2025-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143809949","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rapid Identification of Plastic Beverage Bottles by Using Raman Spectroscopy Combined With Machine Learning Algorithm","authors":"Xinlei Liu,&nbsp;Lei Wang,&nbsp;Wei Li,&nbsp;Jingwei Wan","doi":"10.1002/jrs.6778","DOIUrl":"https://doi.org/10.1002/jrs.6778","url":null,"abstract":"<div>\u0000 \u0000 <p>Rapid and accurate identification of plastic beverage bottles is of great importance because plastic beverage bottles can be encountered as physical evidence in cases involving assaults, thefts, and homicides. In this experiment, 40 commercially available plastic beverage bottles were collected as experimental samples, and their Raman spectral data were collected. Initially, the samples were classified into two categories of polyethylene terephthalate (PET) and polyethylene (PE), and the 35 PET samples were further clustered into three categories by K-means clustering. Savitzky–Golay algorithm smoothing, standard normal variate, multiple scattering correction, and first-order derivatives were utilized to improve the quality of the Raman spectra. A convolutional neural network (CNN) model was constructed for the classification and identification, and four evaluation indexes, such as accuracy, precision, recall, and F1-score, were utilized to compare the model's performance under the four types of preprocessing. The results show that the spectral data preprocessing combining SG and MSC has higher accuracy than other preprocessing methods, and the CNN classification model has the best performance, with 100% correct classification rate in both the training set and the test set, respectively. In conclusion, the results show that convolutional neural networks, when used in combination with Raman spectroscopy, can quickly detect the type of plastic beverage bottle, which is crucial for solving crimes.</p>\u0000 </div>","PeriodicalId":16926,"journal":{"name":"Journal of Raman Spectroscopy","volume":"56 5","pages":"381-388"},"PeriodicalIF":2.4,"publicationDate":"2025-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143831424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Automated Baseline Correction Method for Raman Spectra Based on Piecewise Polynomial Fitting With Adaptive Window","authors":"Jie Ma,&nbsp;Meiyu Zuo,&nbsp;Biwei Wu,&nbsp;Weibo Wang","doi":"10.1002/jrs.6772","DOIUrl":"https://doi.org/10.1002/jrs.6772","url":null,"abstract":"<div>\u0000 \u0000 <p>Baseline background tends to cause the Raman spectral signal to be hidden or distorted, making it difficult to accurately acquire spectral information. Although polynomial fitting has been widely proven to be an effective baseline correction method, it is difficult to achieve both high speed and high accuracy. In this paper, we propose a piecewise polynomial fitting method based on a sliding adaptive window(S-ModPoly). S-ModPoly relies on the adaptive width selection of a sliding window to automatically split the original spectrum into many different length segments containing complete peak information. Low-order iterative polynomial fitting is performed for each segment separately, which greatly reduces the computational effort while improving the baseline fitting accuracy. By further correcting the piecewise fitting results, the discontinuities between different intervals after piecewise fitting are eliminated. Furthermore, the true intensity information of the spectral signal is retained. Here, S-ModPoly is compared with three representative automated methods. The experimental results show that the S-ModPoly method has lower mean error and higher stability in a very short time (less than 20 ms). Additionally, the experimental results on measured Raman spectra demonstrate the effectiveness of the method in automatically processing various real spectral baselines. It performs well in both low and high intensity background baselines.</p>\u0000 </div>","PeriodicalId":16926,"journal":{"name":"Journal of Raman Spectroscopy","volume":"56 4","pages":"337-344"},"PeriodicalIF":2.4,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143809581","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of PuO2 With Visible and UV Raman Spectroscopy: Discrimination Between the Bulk, Surface, and an Intermediate Disordered Layer","authors":"Eliel Villa-Aleman,&nbsp;Jason R. Darvin,&nbsp;Don D. Dick,&nbsp;Thomas C. Shehee,&nbsp;Bryan J. Foley","doi":"10.1002/jrs.6770","DOIUrl":"https://doi.org/10.1002/jrs.6770","url":null,"abstract":"<div>\u0000 \u0000 <p>Raman spectroscopy is an ideal tool in the characterization of materials including PuO₂. The wavelength-dependent absorptivity of the material defines the light penetration depth and the relative Raman scattering contribution from the bulk and the surface. The surface contribution to the total Raman scattering was investigated for PuO₂ calcined at various temperatures and recorded with laser wavelengths of 355, 325, and 244 nm. These experiments provided the first glimpse of the wavelength-dependent disappearance and emergence of new phonons and electronic bands from the PuO₂ surface layers. The first indication of the wavelength transition in the Raman spectra was the loss of the 2LO2 (overtone, ~1155 cm⁻¹) band and the weakening intensity of the Г₁ → Γ₅ electronic band (~2135 cm⁻¹) with the 355-nm excitation laser. The Γ₅ electronic band was barely visible with the 244-nm excitation. The electronic band located at ~1050 cm⁻¹, corresponding to the Г₁ → Γ₄ electronic transition was observed to dramatically increase in intensity while the Г₁ → Γ₃ electronic band (2640 cm⁻¹) sharpened as the UV wavelength was increased in energy from the near- to deep-UV (355–325–244 nm). The FWHM of the T_2g band was found to vary with calcination temperature (450°C and 900°C) with the 325-nm laser and the 244-nm laser. The T_2g band attributes, the strong emergence of the Г₁ → Γ₄ electronic band, and the disappearance of the 2LO2 overtone acquired with the 244-nm excitation for the different calcination temperatures suggest a shallow penetration depth.</p>\u0000 </div>","PeriodicalId":16926,"journal":{"name":"Journal of Raman Spectroscopy","volume":"56 4","pages":"324-336"},"PeriodicalIF":2.4,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143809572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Featured Cover","authors":"Henry Misoi,&nbsp;Jonas I. Hölzer,&nbsp;Thomas Seeger","doi":"10.1002/jrs.6771","DOIUrl":"https://doi.org/10.1002/jrs.6771","url":null,"abstract":"<p>The cover image is based on the article <i>Experimental Determination of the Temperature-Dependent Broadening Effect of Water Vapour on the S-Branch Raman Linewidths of Nitrogen</i> by Jonas Immanuel Hölzer et al., https://doi.org/10.1002/jrs.6742.\u0000\u0000 <figure>\u0000 <div><picture>\u0000 <source></source></picture><p></p>\u0000 </div>\u0000 </figure></p>","PeriodicalId":16926,"journal":{"name":"Journal of Raman Spectroscopy","volume":"56 1","pages":"i"},"PeriodicalIF":2.4,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/jrs.6771","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143115103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DUV Double-Resonant Raman Spectra and Interference Effect in Graphene: First-Principles Calculations","authors":"Ye Zhang,&nbsp;Renhui Liu,&nbsp;Jianqi Huang,&nbsp;Nguyen Tuan Hung,&nbsp;Riichiro Saito,&nbsp;Teng Yang,&nbsp;Zhidong Zhang","doi":"10.1002/jrs.6768","DOIUrl":"https://doi.org/10.1002/jrs.6768","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 &lt;p&gt;We calculate double-resonance Raman (DRR) spectra of monolayer graphene by first-principles density functional calculation, for wide laser excitation energies from the near-infrared (1.58 eV) to the deep-ultraviolet (DUV, 5.41 eV) region. When laser excitation energy, \u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;E&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;L&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;&lt;/math&gt;, goes into the DUV region, Raman peak wavenumber for G\u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msup&gt;\u0000 &lt;mrow&gt;&lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;∗&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;&lt;/math&gt; band switches from red-shift to blue-shift and for 2D\u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msup&gt;\u0000 &lt;mrow&gt;&lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;′&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;&lt;/math&gt; band switches from red-shift to constant, in contrast to the continuous blue-shift of G\u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msup&gt;\u0000 &lt;mrow&gt;&lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;′&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;&lt;/math&gt; band. Raman intensity of the three bands generally decreases with increasing \u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;E&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;L&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;&lt;/math&gt;, except for \u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;E&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;L&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;&lt;/math&gt; around 4.08 eV where Raman intensity diverges due to van Hove singularity of electron density of states. The combined two-phonon modes change with \u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msub&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;E&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;L&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msub&gt;&lt;/math&gt; for both G\u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msup&gt;\u0000 &lt;mrow&gt;&lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;′&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;&lt;/math&gt; and G\u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msup&gt;\u0000 &lt;mrow&gt;&lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;∗&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;&lt;/math&gt; bands (e.g., from 2LO to 2TO and back to 2LO for G\u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msup&gt;\u0000 &lt;mrow&gt;&lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;′&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;&lt;/math&gt; and from LA + LO/TO to TA + LO/TO for G\u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msup&gt;\u0000 &lt;mrow&gt;&lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;∗&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/msup&gt;&lt;/math&gt;) but remain 2LO for 2D\u0000&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;msup&gt;\u0000 &lt;mrow&gt;&lt;/mrow&gt;\u0000 &lt;mrow&gt;\u0000 ","PeriodicalId":16926,"journal":{"name":"Journal of Raman Spectroscopy","volume":"56 4","pages":"316-323"},"PeriodicalIF":2.4,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143809864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}