Easy sampling of solids, powders, gels, liquids, slurries, and aqueous solutions No sample preparation Sampling through windows, transparent containers, blister packs, or by immersion Remote sampling using fiber optic probes (up to 100 meters) Sharp spectral peaks for quantitative and qualitative analysis
Similar to an infrared spectrum, a Raman spectrum consists of a wavelength distribution of bands corresponding to molecular vibrations specific to the sample being analyzed. In practice, a laser is focused on the sample, the inelastically scattered radiation (Raman) is optically collected, and directed into a spectrometer, which provides wavelength dispersion, and a detector converts photon energy to electrical signal intensity. Historically, the very low conversion of incident radiation to inelastic scattered radiation (1 in 109) limited Raman spectroscopy to applications that were difficult to perform by infrared spectroscopy, usually aqueous solutions. Real-time chemical analysis can be performed in a non-contact manner. The wavelengths and intensities of the scattered light can be used to identify functional groups of molecules because each compound has its own unique Raman spectrum which can be used as a finger print for identification. It has found wide application in the chemical, polymer, semiconductor, and pharmaceutical industries because of its high information content.
We have seen good enhancement at all wavelengths from 532 to 1064 nm.
We typically acquire our spectra using 100 mW of 785 nm laser excitation focused at the sample. We find that 50 – 200 mW yields best results, but the higher laser power may induce sample or substrate degradation
Yes, for the best results the laser should be focused just inside the inner wall of the vial. However, if the laser focal spot is into the glass wall o the vial then the spectrum will mainly be glass
Typically carboxylic acids, aromatic amines, heterocyclic pyridine compounds, amino acids, etc.