M. Maiwald, B. Eppich, A. Ginolas, B. Sumpf, G. Erbert, G. Tränkle

Published in:

Appl. Spectrosc., vol. 69, no. 10, pp. 1144-1151 (2015).

Abstract:

A compact handheld probe for shifted-excitation Raman difference spectroscopy (SERDS) with an implemented dual-wavelength diode laser with an emission at 785 nm is presented. The probe is milled from aluminum and has dimensions 100 × 28 × 12 mm. The diode laser provides two excitation lines with a spectral distance of 10 cm^-1 (0.62 nm), has a spectral width smaller than 11 pm, and reaches an optical power of 120 mW ex probe. Raman experiments were carried out using polystyrene (PS) as the test sample. During a measurement time of over 1 h, a stable spectral center position of the Raman line at 999 cm^-1 of PS was achieved within a spectral window of 0.1 cm^-1. Here, the Raman intensity of this line was observed with a peak-to-peak variation smaller than ±2%, dominated by shot noise interference. A deviation of the center position of a Raman line with <±1 cm^-1 was observed over the whole excitation power range. Raman investigations of the quartz glass window of the SERDS probe showed minor interference. The results demonstrate the suitability of the developed handheld probe for Raman investigations and the application of in situ SERDS experiments to fields such as food safety control, medical diagnostics, and process control.

Keywords:

Dual-wavelength diode laser; 785 nm; Raman spectroscopy; Shifted excitation Raman difference spectroscopy; SERDS; Handheld probe.

Copyright © 2015 Society for Applied Spectroscopy. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from Society for Applied Spectroscopy.

Full version in pdf-format.