Optoacoustic detection of different doping substances commonly used by athletes with an optical parametric generation laser source

摘要

In this paper, we present first results of a spectral characterisation of doping substances using a resonant optoa-coustic cell and a Nd:YAG laser pumped optical parametric generation (OPG) laser source in the mid-infrared wavelength range between 3.0 and 4.0 μm with periodically poled LiNbO_3 as nonlinear medium for the frequency conversion. Single spectra covering a wavelength range of about 220 nm can be conducted within less than 2 hours (3s averaging time, 7s between consecutive data points, about 0.3nm step-width). Despite the large linewidth of the OPG source of 240 GHz (8 cm~(-1)), the laser spectrometer is well suited for the spectral analysis of these large organic molecules as they exhibit structured continuum absorption over a wide spectral range rather than isolated absorption peaks. We present measured spectra of ephedrine, alprenolol, ethacrynic acid, etc. and discuss the potential of laser-based detection of doping substances both as a supplement to existing methods and in view of a fast in situ screening technique at sporting events.