Carbon Analysis with High Signal Throughput Portable Raman Spectroscopy

Importance of the topic

Carbon nanomaterials such as graphene, graphite, carbon nanotubes and carbon black are increasingly employed across sectors including energy storage, composites and advanced manufacturing. Their structural features at the nanoscale dictate key properties like electrical conductivity, mechanical strength and thermal stability. As production volumes rise, fast and reliable characterization methods become essential for quality control and research and development. Raman spectroscopy offers a nondestructive, rapid and selective way to probe the microcrystalline structure of these materials and to monitor manufacturing consistency.

Objectives and overview of the study

This work demonstrates high signal-throughput portable Raman spectroscopy applied to diverse carbon allotropes. The main goals are to outline spectral features of key materials, to establish a simple quality-control metric based on the D and G band intensity ratio, and to show how a portable system can be integrated safely into manufacturing environments. The study provides guidelines for data acquisition, baseline correction and quantitative analysis in line with relevant standards.

Methodology and instrumentation

Measurements were carried out using a compact i-Raman Prime 532H system operating at 532 nm excitation. Sample interrogation employed a fiber-optic probe mounted in an XYZ-adjustable holder and an optional ergonomic enclosure converting a class 3B laser output into a class 1 emission for safe use on the production floor. Typical operating parameters included 30–90 s acquisition times and laser power around 34 mW. Baseline correction and peak intensity extraction were performed in BWSpec software, following ASTM E3220-20 guidelines for graphene flake characterization. The intensity ratio I D / I G served as a semi-quantitative indicator of structural disorder.

Instrumentation details

• System model i-Raman Prime 532H with embedded tablet
• Laser wavelength 532 nm
• Accessories: XYZ probe holder BAC150B, optional video microscope BAC151C-532, optional E-grade probe for SWCNT analysis
• Software: BWSpec for data acquisition and analysis

Main results and discussion

Raman spectra of different carbon nanomaterials exhibit three principal features: the G-band near 1580 cm⁻¹ indicative of sp² in-plane vibrations, the disorder-sensitive D-band around 1350 cm⁻¹, and the 2D-band overtone of the D-band. Key observations include:

• Pristine graphene shows a sharp G-band, a pronounced 2D-band and essentially no D-band, with an I2D/IG ratio close to 2
• Graphite presents a broadened and asymmetric 2D-band and lower I2D/IG values
• Single-walled carbon nanotubes feature a split G-band into G+ and G⁻ modes due to tube curvature
• Carbon black powders display strong, broad D-bands and high I D / I G ratios above 0.5, indicating low crystallinity
• Carbon nanofibers produce intense D-bands with I D / I G ratios varying widely, reflecting diverse disorder levels

The calculated I D / I G ratio correlates directly with the degree of structural disorder and enables rapid pass/fail assessment in quality-control workflows. Baseline-corrected peak intensities exported from BWSpec facilitate standardized reporting.

Benefits and practical applications

Raman spectroscopy of carbon nanomaterials offers:

• Noninvasive, rapid spectral acquisition suitable for inline or offline testing
• A simple quality-control parameter (I D / I G) for monitoring batch consistency
• Portability and safety features that allow deployment on manufacturing floors
• Capability to distinguish among graphene quality grades, nanotube types and amorphous carbon powders

These advantages support R&D optimization, raw material verification and process control in industries such as battery production, polymer composites and additive manufacturing.

Future trends and possibilities

Emerging developments likely to expand the role of Raman analysis include:

• Integration with automated production lines and robotics for real-time monitoring
• Advanced algorithms and machine learning for spectral deconvolution and defect classification
• Extension to multiwavelength and hyperspectral Raman imaging for deeper structural insight
• Development of miniaturized and handheld devices for field and point-of-care applications
• Broader adoption of standardized data formats and cloud-based analysis platforms

Conclusion

Portable high-throughput Raman spectroscopy provides a powerful toolset for characterizing carbon nanomaterials. By focusing on the D and G-band intensity ratio, researchers and manufacturers can implement a straightforward and reproducible quality-control metric. The combination of rapid data acquisition, safe operation and robust software analysis positions this methodology for growing adoption across industrial and research settings.

References

• A C Ferrari Solid State Communications 143 47–57 (2007)
• ASTM E3220-20 Standard Guide for Characterization of Graphene Flakes, ASTM International, West Conshohocken, PA, 2020