Introduction

Analysis using a Raman spectrometer does not typically require any sample pretreatment; measurement can be performed non-destructively and without direct contact. Therefore, it is possible to evaluate the component distribution while maintaining the sample integrity. In addition, with the JASCO Particle Analysis program it is also possible to evaluate the variation in particle size and shape, etc. The particle size distribution can be displayed as a histogram together with sample shape information from the observed image, combined with the chemical images. This method is particularly useful for the analysis of a variety of different materials such as resins, foods, pharmaceuticals, and microplastics.

In this article, we evaluated the distribution of diamond in a diamond polishing sheet using particle analysis software.

NRS-5500 Raman spectrometer

Experimental

A diamond polishing sheet was placed on the stage for imaging measurement.

Measurement conditions
Ex wavelength:  532 nm
Objective lens:   50x Long working distance
Measurement interval:  3 µm
Measurement points:  170 x 170 points (Approx. 500 x 500 µm)
Exposure time:  0.03 seconds
Accumulation:  1

Results

In addition to diamond, cerium oxide (a glass abrasive compound) was detected in the spectrum shown in (b). When a chemical image was created using peak height for the diamond peak indicated by the blue arrows in the spectrum, it was confirmed that the diamond particles were distributed as shown in (c).

In addition, (e) and (f) show the results of analysis of (c) using JASCO Particle Analysis*. (e) is a histogram in which the particle size (diameter calculated as the equivalent circle diameter) is plotted on the Y-axis, with its almost normal distribution on the X-axis. Also, from the correlation distribution of particle size and circularity shown in (f ), higher circularity is found for particles near the average size value or smaller (especially 4 µm or less). While larger particles have a lower circularity, with a greater number of ellipse- or rod-shapes. Particle analysis using histograms and correlation distributions can be useful when controlling the size and shape of the components in a final product or when evaluating products from different manufacturing processes or from different lots.

*With JASCO Particle Analysis, in addition to acquiring the size, area, circularity, aspect ratio, etc. of each particle, histograms (which can be converted into stacked histograms), frequency distribution tables, and correlation distributions can be created easily.

Conclusion

Raman spectroscopy can generally be used to evaluate the component distribution with non-destructive, non-contact, and no pretreatment of the sample. Detailed analysis is possible by visualizing the component distribution and acquiring the shape information using the JASCO Particle Analysis application.