In this interview, industry experts Sudhir Dahal and Matt Gabel, discuss the transformative role of Raman spectroscopy in advancing material science, highlighting its applications in batteries, graphene, semiconductors, and next-generation material research.
What is Raman spectroscopy, and what makes it such a valuable tool in material science?
Sudhir: Raman spectroscopy is a powerful optical technique in which a laser excites a sample and we analyze the scattered light to gain molecular insights. It is incredibly sensitive to bond strength, angles, and structural changes, making it indispensable for identifying compounds and even distinguishing between similar ones. What is unique about Raman is its non-destructive nature, with no sample preparation needed. You can measure it in real-time and even through containers, and its versatility spans analyzing batteries, graphene, semiconductors, and many other materials.
How does Raman spectroscopy contribute to advancements in battery technology?
Sudhir: Raman spectroscopy is an invaluable technique for critical areas of lithium-ion battery research and production. It plays a key role in:
- Raw Material Processing: It monitors lithium carbonate production almost instantly, ensuring high yields and an efficient process.
- Component Analysis: Raman can map chemical compositions and spatial distributions by analyzing anode and cathode materials. For instance, it distinguishes graphite and carbon black layers in anodes, even detecting subtle stress or chemical changes post-use.
- Quality Control: Raman microscopy can image separator layers, detecting issues like insufficient thickness that might lead to battery failures. Its ability to analyze without damaging samples makes it critical for advancing safety and reliability.
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Why is Raman spectroscopy ideal for studying graphene?
Matt: Graphene, a single layer of carbon atoms in a hexagonal lattice, has exceptional strength and conductivity. Raman spectroscopy can differentiate graphene from graphite or other carbon materials by its unique G-band and 2D-band peaks. Even subtle shifts in these peaks indicate the number of layers or structural quality. Beyond single-point analysis, Raman microscopy maps growth patterns, defects, and homogeneity. This non-contact, precise approach accelerates graphene research and ensures the high-quality production of this game-changing material.
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What role does Raman spectroscopy play in semiconductor research?
Matt: Semiconductors rely heavily on uniform crystallinity and precise dopant placement. Raman spectroscopy analyzes crystallinity, detects defects, and maps mechanical strain in materials like silicon, molybdenum disulfide (MoS2), and tungsten disulfide (WS2). For instance, small shifts in peak positions reveal stress, strain, or doping effects. It is particularly exciting in next-gen materials like 2D semiconductors, where Raman identifies monolayers, maps thickness, and even tracks strain in multilayered configurations.
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How does Raman microscopy add value to these analyses?
Matt: Raman microscopy combines spectroscopic precision with spatial imaging. For example, it maps out how graphene nucleates and grows or reveals defects and thickness variations in 2D semiconductors. Its applications extend to mapping strain distributions or differentiating multilayered regions from monolayers. This spatial insight helps researchers optimize processes like chemical vapor deposition (CVD) for graphene or ensure semiconductor uniformity in industrial applications.
What is the significance of Raman spectroscopy in analyzing stress or strain in materials?
Matt: Raman’s sensitivity to structural changes makes it a perfect tool for measuring stress and strain. The shifts in peak positions directly correlate with strain percentages. However, accuracy depends on proper calibration and controlling variables like material purity, layer thickness, and dopants. For example, in MoS2, Raman maps energy changes in the lattice vibrations due to mechanical stress, providing insights that other techniques might miss.
Can Raman spectroscopy handle extreme sampling environments or temperature-dependent studies?
Matt: Temperature-controlled cells allow Raman to capture how materials change under heating or cooling. For semiconductors, these temperature-driven shifts in crystallinity are often crucial to study. We also use flow cells for controlled atmospheres, preventing oxidation, and even electrochemical cells to analyze materials under applied currents. These tools expand Raman's capability to simulate real-world conditions.
How does Raman spectroscopy support high-resolution analysis in research and industry?
Matt: Raman achieves submicron resolution, which is limited by laser wavelength. With a 532 nm laser and a 100x objective, spot sizes reach ~532 nm, making it suitable for mapping domains or thin films. Higher magnification creates localized power density, enabling detailed, high-speed analysis. It is ideal for semiconductors or any study requiring precise spatial resolution.
What is the potential of Raman spectroscopy for next-generation material research?
Sudhir: Raman spectroscopy is essential for developing innovative materials. Its ability to map, monitor, and measure changes in real-time makes it invaluable for emerging fields like 2D semiconductors and graphene-based technologies. Coupled with techniques like photoluminescence (PL) mapping, Raman provides a fuller picture of material properties, from stress analysis to purity verification. The future lies in leveraging its adaptability and non-destructive precision to meet the demands of advanced industries.
About Sudhir Dahal 
Sudhir Dahal is a Product Manager at Thermo Fisher Scientific, specializing in Raman microscopes and benchtop Raman spectrometers. With over seven years of experience in spectroscopy techniques across the industry, he brings deep expertise to his role. Sudhir earned his PhD from the University of Maryland Baltimore County, where he collaborated on pioneering spectroscopy-based methods for brain tumor cell detection, highlighting his passion for advancing scientific technologies.
About Matt Gabel 
Matt is a Raman Application Scientist at Thermo Fisher Scientific. He earned his PhD in Physics from Washington State University, where he focused on studying the ferroelectric properties of semiconductors. His expertise in vibrational spectroscopy deepened during his time as a visiting researcher at Pacific Northwest National Laboratory, where he explored semiconductor materials using tip-enhanced Raman spectroscopy.
This information has been sourced, reviewed and adapted from materials provided by Thermo Fisher Scientific – Vibrational Spectroscopy
For more information on this source, please visit Thermo Fisher Scientific – Vibrational Spectroscopy
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