Non-destructive NIR-FT-Raman spectroscopy of plant and animal tissues, of food and works of art

Just after the discovery of Raman spectroscopy in 1928, it became evident that fluorescence with a quantum yield of several orders of magnitude higher than that of the Raman effect was a great and apparently unbeatable competitor. Raman spectroscopy could therefore, in spite of many exciting advantages during the last 60 years, not be applied as an analytical routine method: for nearly every sample, fluorescing impurities had to be removed by distillation or crystallisation. Purification, however, is not possible for cells and tissues, since the removal of the fluorescing enzymes and coenzymes would destroy the cells. There is fortunately one alternative solution. When excited with the radiation of the Nd:YAG laser at 1064 nm Raman spectra are practically free of fluorescence. Raman spectra can now be recorded with minimal sample preparation. In order to facilitate non-destructive Raman spectroscopy of any sample, cells and tissues, food, textiles and works of art, a new entrance optics for Raman spectrometers is used. Typical results from several fields are demonstrated.