In this interview, Dr. Joshua Lea explores the role of the integration of Raman spectroscopy with SEM technology for advanced materials analysis.
Can you introduce yourself and the topic you will be discussing today?
My name is Dr. Joshua Lea, and I am the RISE Product Scientist at Oxford Instruments. I am delighted to introduce you to our RISE system, a novel combination of Raman Imaging and Scanning Electron Microscopy (SEM).
The RISE system is intended to give a thorough and complementary study of materials by combining the capabilities of Raman spectroscopy and SEM. This integration enables researchers and engineers to collect extensive information on the chemical composition, molecular structure, and morphology of materials in a single process, providing a formidable tool for advanced material analysis.
What is Raman spectroscopy, and how was it discovered?
Raman spectroscopy is a technique that uses light scattering to obtain molecular-level information about materials. Discovered by Sir C.V. Raman in 1928, this method involves analyzing how light scattered by molecules changes in energy, which reveals details about the molecules' vibrational modes. This groundbreaking discovery allowed scientists to investigate the molecular composition and structure of materials non-destructively.
How does Raman scattering differ from Rayleigh scattering?
Raman scattering and Rayleigh scattering both involve the interaction of light with molecules, but the results vary. Rayleigh scattering occurs when light is dispersed without any change in energy, implying that the scattered light has the same wavelength as the incoming light.
On the other hand, Raman scattering causes a change in the energy of the dispersed light. This movement in energy, whether up or down, offers information about the molecules' vibrational modes, which we evaluate using Raman spectroscopy.
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What information can we obtain from a Raman spectrum?
A Raman spectrum may reveal a great deal about a material's molecular makeup and structure. Analyzing energy changes allows us to detect various chemical bonds and even discriminate between different phases of a substance.
Raman, for example, distinguishes between graphitic and amorphous phases in carbon materials. It is especially sensitive to changes in chemical composition while charging and discharging, which makes it very useful for investigating battery materials and other dynamic systems.
How is Raman microscopy integrated with Scanning Electron Microscopy (SEM) in the RISE system?
The RISE system incorporates Raman microscopy directly into the chamber of a SEM. This combination enables us to utilize SEM to find and analyze regions of interest based on material and diffraction contrast.
Then, without moving the sample, we use Raman microscopy to collect chemical and structural fingerprint data. The integration is seamless, allowing for extensive and complimentary research of the same region while using the benefits of both methodologies.
What are some advantages of the RISE system?
One of the primary benefits of the RISE system is its ability to deliver a complete image of a material. While SEM provides precise pictures and elemental composition via EDS (Energy Dispersive Spectroscopy), Raman adds molecular information such as chemical bonding and phase distribution.
This combination enables more comprehensive material characterization. Additionally, Raman microscopy can be performed on uncoated materials with minimal preparation and is non-destructive, preserving the sample for future research.
Can you describe the process of analyzing a sample using the RISE system?
The procedure starts with putting the sample in the SEM chamber, where we utilize the electron microscope to identify regions of interest based on morphology or diffraction contrast.
Once recognized, we switch to Raman mode to collect chemical and structural information. If the sample is laser-transparent, we can use 3D confocal imaging to see particles or phases concealed inside the material. Finally, we may return to SEM and do further studies, such as EDS, to ensure a comprehensive and detailed knowledge of the material.
What are some applications of Raman microscopy in materials analysis?
Raman microscopy is highly versatile and applicable across various fields. For instance, in the study of battery materials, it can be used to reveal how different grains in a cathode material influence the charging process. In concrete analysis, Raman microscopy can differentiate between hydrated and non-hydrated phases, offering insights into the material's structural stiffness.
It is also useful in geological research, where it can identify minerals and their structural states, as well as in the examination of 2D materials such as molybdenum disulfide, where it can discriminate between monolayers and multilayers and detect flaws.
How does Raman imaging help in analyzing pharmaceutical products?
In pharmaceutical analysis, Raman imaging provides detailed chemical information that complements the elemental analysis obtained from EDS.
For example, in dietary supplements, Raman imaging can reveal chemical interactions in carbon-rich regions, allowing for the identification of specific molecules like maltoheptaose, a type of starch. Additionally, it can differentiate between excipients, such as hydromagnesite in a tablet, which is crucial for understanding the product's composition and stability.
What are the benefits of combining EDS and Raman spectroscopy in the RISE system?
Incorporating EDS and Raman spectroscopy into the RISE system provides a comprehensive perspective of materials. EDS determines elemental content, while Raman identifies molecular structure and chemical bonds.
This dual technique is highly advantageous because it allows us to combine elemental data with molecular information. For instance, while EDS might struggle to differentiate between polymers in a blend, Raman spectroscopy can easily identify them through their unique spectral fingerprints. Due to their complementary nature, the RISE system is an effective tool for conducting comprehensive materials analysis.
This information has been sourced, reviewed and adapted from materials provided by Oxford Instruments Nanoanalysis.
For more information on this source, please visit Oxford Instruments Nanoanalysis.
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