Comparison of SPELEC RAMAN and standard Raman microscopes

Significance of the topic

Analytical Raman spectroscopy is widely used for material characterization, yet conventional confocal Raman microscopes can yield non-representative results in heterogeneous samples due to their small laser spot size. A new integrated spectroelectrochemical Raman instrument, SPELEC RAMAN, offers a larger sampling area, combined electrochemical capability, and improved reproducibility in a compact and user-friendly design.

Objectives and overview of the study

The study compares the performance of a standard confocal Raman microscope with the SPELEC RAMAN instrument. Using single-walled carbon nanotubes (SWCNTs) as a model, the work evaluates spot-size effects, measurement reproducibility, instrument versatility, and ease of integration with electrochemical cells.

Methodology and instrumentation

The sample consisted of SWCNTs placed in an aluminum crucible within a Raman spectroelectrochemical cell. Conventional Raman measurements were made at four distinct 0.5–10 µm spots using a confocal microscope. SPELEC RAMAN measurements employed a 785 nm laser, a 190 µm diameter Raman probe, and DropView SPELEC software to synchronize electrochemical control and spectral acquisition.

Main results and discussion

– Standard microscope measurements showed significant variability in the D/G band intensity ratio (I_D/I_G), ranging from 0.448 to 0.843 (RSD 26.4%).
– A single SPELEC RAMAN spectrum yielded I_D/I_G = 0.701, matching the average of the four confocal measurements. Reproducibility across four SPELEC RAMAN spectra was high (average I_D/I_G = 0.718, RSD 1.97%).
– The larger focal area allows the use of higher laser power without sample damage and provides representative bulk information in one shot.
– The Raman probe’s 8 mm focal distance and universal fiber connectors enable coupling with various cells, including screen-printed and conventional electrodes.

Benefits and practical applications

– Representative bulk analysis with a single measurement reduces time and cost.
– Integrated electrochemical and spectroscopic measurements simplify operando studies.
– Compact size and portability facilitate deployment in gloveboxes or field environments.
– Intuitive DropView SPELEC software allows real-time monitoring, baseline correction, and automated data processing without specialist training.

Used instrumentation

• SPELEC RAMAN spectroelectrochemical instrument (785 nm laser)
• RAMANPROBE reflection Raman probe
• RAMANCELL spectroelectrochemical cell for screen-printed electrodes
• DropView SPELEC software for synchronized electrochemical and spectroscopic control

Future trends and possibilities

Expanding SPELEC RAMAN to on-line process monitoring, industrial quality control, and in-situ studies in harsh environments. Integration with advanced SERS substrates and multi-modal spectroscopies may further enhance sensitivity and selectivity. Customizable probe designs and software upgrades will support new electrochemical systems and materials research.

Conclusion

SPELEC RAMAN outperforms standard Raman microscopes in representativeness, reproducibility, and operational simplicity. Its integrated design and versatile probe make it a valuable tool for routine and operando Raman spectroelectrochemical analyses across research and industrial laboratories.

Reference

• AN-RA-002 The carbon battle characterization of screen-printed carbon electrodes with SPELEC RAMAN
• AN-RA-003 In situ, fast and sensitive: Electrochemical SERS with screen-printed electrodes
• AN-RA-005 Characterization of single-walled carbon nanotubes by Raman spectroelectrochemistry
• AN-RA-006 New strategies for obtaining the SERS effect in organic solvents
• AN-RA-007 Enhancement of Raman intensity for the detection of fentanyl
• AN-RA-008 Easy detection of enzymes with the electrochemical-SERS effect