värähtelyspektroskopian

Värähtelyspektrometria, often translated as vibrational spectroscopy, is a family of spectroscopic techniques that measure the vibration of molecules. These vibrations are unique to each molecule and can be used to identify and characterize substances. The fundamental principle behind vibrational spectroscopy is that chemical bonds within a molecule can absorb or emit energy at specific frequencies corresponding to their vibrational modes. When a molecule is exposed to electromagnetic radiation, it can absorb photons at these characteristic frequencies, causing it to transition to a higher vibrational energy level.

The most common techniques in vibrational spectroscopy are infrared (IR) spectroscopy and Raman spectroscopy. Infrared spectroscopy works by passing infrared light through a sample and measuring which wavelengths are absorbed. These absorbed wavelengths correspond to the vibrational frequencies of the molecule. Raman spectroscopy, on the other hand, uses a monochromatic light source, typically a laser, and observes the light that is scattered by the sample. A small fraction of this scattered light is shifted in frequency (Raman scattered light), and this frequency shift is directly related to the vibrational modes of the molecule.

Both IR and Raman spectroscopy provide complementary information about molecular vibrations. IR spectroscopy is generally more sensitive to vibrations that involve a change in dipole moment, while Raman spectroscopy is more sensitive to vibrations that involve a change in polarizability. The resulting spectra, plots of intensity versus frequency or wavenumber, serve as a unique fingerprint for a given molecule. This makes vibrational spectroscopy a powerful tool in various fields, including chemistry, materials science, biology, and pharmaceuticals, for purposes such as compound identification, purity assessment, and structural elucidation.