Development of measures for metrological support of Raman spectroscopy

Abstract

The method of Raman spectroscopy (RS) is widely used for timely metrological support of technological lines of the industrial sector in the chemical, medical and pharmaceutical, food, as well as criminalistics and forensic examinations. The wide application of the Raman spectroscopy method requires the use of specific metrological support tools, namely, measures for calibrating Raman spectrometers and microscopes according to the spectrum shape (i. e. relative spectral sensitivity).The purpose of the research was to develop prototype measures designed to calibrate Raman spectrometers and microscopes on a scale of relative intensities provided with metrological traceability to the SI base units.Prototype measures were made from inorganic glasses based on an oxide matrix, each of the glasses was activated with metal ions selected to excite a broad fluorescence line with radiation at a given wavelength: 532 nm (manganese ions), 633 nm (bismuth ions) and 785 nm (chromium ions). Metrological characteristics were established for prototype measures, where the certified characteristic is the relative intensity of the reproduced fluorescence radiation. The maximum expanded measurement uncertainty of the relative fluorescence intensity at a coverage factor k = 2 was determined, which is 9.4 %, 5.2 % and 2.8 % for prototype measures designed to reproduce the relative fluorescence intensity when excited at wavelengths of 532 nm, 633 nm and 785 nm, respectively.Certification of measures performed on the laser Raman confocal microscope Confotec NR500, which is part of the GET 196-2015 standard, allows establishing metrological traceability through the scale of relative intensities of the GET 8 6-2017 microscope, providing traceability to SI units of the “(light) energy flux” value. Thus, it is possible to find the spectral correction function for determining the Raman spectra traceable to the State Primary Standard GET 196-2015 for calibrated devices using certified measures.The practical significance of the results of the research makes it possible to expand the possibility of establishing and monitoring the stability of the calibration characteristics of microscopes and Raman spectrometers, namely, it allows calibration on a scale of relative intensities.