Introduction

Raman and infrared spectroscopy are well known as complementary techniques to study molecular structure and molecular function. In addition, UV-visible spectroscopy represents an optional orthogonal assessment. Although orthogonal assessment has been proven to be useful in quality analysis, it is a challenge to accurately synchronize the measurement position at the microscopic level across different systems, such as Raman, IR and/or UV-visible microscopy. To overcome this barrier, we have developed ‘IQ Frame’, a sample holder that can be easily transferred among Raman, FTIR and UV-visible micro-spectrometers.

In this article, some applications included imaging measurement using IQ Frame and the features of these systems are introduced.

Features

• Shared sample holder for orthogonal assessment by micro-spectrometers
• Exact position matching is performed following two steps; First, using measurement coordinates stored in a spectrum data file, roughly select the measurement position. Second, using the image stored in the measurement data file and the live visible image, fine adjustment can be made to the stage until the sample position is perfectly matched to the previous measurement.

Experimental

Application 1: Orthogonal Assessment of Micro Fabrics by UV-Visible, Raman and FTIR Micro-Spectrometers

Sample: Colored ( green, blue ) fabrics

Visible image

Method: Using IQ Frame, measured identical position of each fabric by UV-visible, Raman and FTIR
Results (UV-Vis):

UV-Vis reflection spectra (Contributed to determine excitation laser wavelength for application of resonance Raman)

Result of color evaluation ( UV-Vis, Identified their color)

Results (Raman):

Raman spectra (left) and result of database search (right) (Identified their colorant (dye))

Results (IR):

IR (ATR) spectra (left) and result of database search (right) (Identified their chemical composition)

Micro-UV-visible spectra were used to analyze the fabric colors. In addition, the UV-visible spectra were used for determination of the excitation laser wavelength for Raman measurement. In the measurement of these samples, the laser wavelength close to their absorption maximum ( 532 nm for Fabric 1 and 633 nm for Fabric 2 ) are selected. From the Raman data, we could identify information about the dyes using the phenomenon of resonance Raman. Lastly, using FTIR with micro-ATR measurement, the chemical composition of the fabrics could be determined.

Application 2: Complementary Imaging Analysis of Plastics by Raman and FTIR Micro-Spectrometers

Sample  Plastic particles embedded and pressed in KBr plate

Visible image

Method  Using IQ Frame, imaging measurement are performed by Raman and FTIR micro-spectrometer at the identical position.

Results  Using both Raman and IR enabled to detect 6 components. Because protein could be detected by only IR due to fluorescence in Raman and carbon could be detected by only Raman though four types of polymers could be detected by both Raman and IR.

Keywords

Raman, infrared spectroscopy, molecular structure, UV-Visible, micro-spectrometers, orthogonal assessment, IQ Frame, FTIR

Results

• ‘IQ Frame’ is designed for seamless analysis among JASCO Raman, FTIR and UV-visible microscopes.
• ‘IQ Frame’ Enables seamless analyses among micro-spectrometers based on coordinates information of measurement point and coincidence of visible images between each measurement.
• Applications for complementary imaging and orthogonal assessment by multiple micro-spectrometers are introduced.

References

Poster Session at ICORS (27th International Conference on Raman Spectroscopy, August 14 – 19, 2022, in Long Beach, California, USA)

Carlos Morillo¹, Kohei Tamura², Yuji Higuchi², Erika Taira², Kento Aizawa², Satoko Suzuki², Ken-ichi Akao^2
1JASCO Incorporated, 28600 Mary’s court, Easton, Maryland 21601, USA
²JASCO Corporation, 2967-5 Ishikawa-machi, Hachioji, Tokyo 192-8537, Japan