Evaluation of the component distribution and particle analysis using micro Raman spectroscopy

Download PDF May 11, 2021

Introduction

Figure 1. NRS-5500 Raman Spectrometer

Analysis using Raman a spectrophotometer 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 application note, we evaluated the distribution of diamond in a diamond polishing sheet using particle analysis software.

Experimental

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

Measurement Conditions
Main UnitNRS-5500 Raman spectrometerMeasurement Points170 x 170 points
(Approx. 500 x 500 µm)
Ex Wavelength532 nmMeasurement Interval3 µm
Exposure Time0.03 secondsAccumulation1
Objective Lens50x Long working distance

Keywords

Raman spectroscopy, QRi, mapping, particle analysis, diamond

Results

Figure 2 shows the results of imaging measurement and analysis, 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.

Figure 2. Analysis result

*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.

<Regarding imaging measurement>
Measurement took approx. 20 minutes (using QRI).
A spectrum  with accepatable S/N was obtained for analysis with an exposure time per point of 0.03 sec (30 msec). Shortening the acquisition time or changing to a faster EMCCD detector, it is possible to further reduce the measurement time.

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.

System Configuration
ModelDescriptionP/NRemarks
Main UnitNRS-5500Raman Spectrometer7119-J051A
532 nm laser
100 mW laser was used, but a standard 50 mW is also available.
OptionsQRI 5000/7000QRI option7119-J278A
#rowspanRHG5-600B500600 gr/mm grating6947-J293A
#rowspanLMPLFLN 50xObjective lens1108-0102Long work distance
#rowspanJASCO particle analysisCustomized program

<Regarding imaging measurement>

Measurement took approx. 20 minutes (using QRI).

A spectrum  with accepatable S/N was obtained for analysis with an exposure time per point of 0.03 sec (30 msec). Shortening the acquisition time or changing to a faster EMCCD detector, it is possible to further reduce the measurement time.

About the Author

Dr. Carlos Morillo received his Post Doc at Advanced Industrial Science & Technology in Fukuoka and was a Research Scientist at Kyushu University in Japan where he lived for several years. Carlos received his Doctor of Engineering from Kyushu University and his Masters and BS from Simon Bolivar University in Caracas Venezuela. He is an Applications Scientist at JASCO.