From the variety of applications of lasers in chemistry, we shall mention:
· Excitation of molecules to specific levels, and examination of the emitted radiation.
· Measurements of the relaxation time of specific excited levels of molecules.
· Disruption of chemical bonds in molecules at specific region - When a laser beam is focused, a very high electric field is created at the focal point (up to 109 V/cm). Such electric fields are larger than the force which holds the valence electrons in an atom. Another possibility is to use wavelengths which are very short (which means that the photons are very energetic) to break the chemical bonds. This is usually done with the Excimer laser.
· Raman spectroscopy: Raman scattering is a process of inelastic scattering of the photon by the molecule. The photon is absorbed by the molecule, and another photon, with a different frequency is emitted. The change in frequency of the photon is connected to the energy transitions in the molecule which absorb the photon. The most important Raman scattering is connected to vibrational transitions of the molecule. By measuring the change in frequency, it is possible to identify the specific molecule.
There are two kind of Raman scattering processes:
o Stokes scattering - when the photon lose energy, and the molecule absorb this energy, and go into excited state. The frequency of the emitted photon is less than the frequency of the incident photon.
o Anti-Stokes scattering - when the photon receives energy from the molecule. The frequency of the emitted photon is higher than the frequency of the incident photon.
· Excitation of molecules to specific levels, and examination of the emitted radiation.
· Measurements of the relaxation time of specific excited levels of molecules.
· Disruption of chemical bonds in molecules at specific region - When a laser beam is focused, a very high electric field is created at the focal point (up to 109 V/cm). Such electric fields are larger than the force which holds the valence electrons in an atom. Another possibility is to use wavelengths which are very short (which means that the photons are very energetic) to break the chemical bonds. This is usually done with the Excimer laser.
· Raman spectroscopy: Raman scattering is a process of inelastic scattering of the photon by the molecule. The photon is absorbed by the molecule, and another photon, with a different frequency is emitted. The change in frequency of the photon is connected to the energy transitions in the molecule which absorb the photon. The most important Raman scattering is connected to vibrational transitions of the molecule. By measuring the change in frequency, it is possible to identify the specific molecule.
There are two kind of Raman scattering processes:
o Stokes scattering - when the photon lose energy, and the molecule absorb this energy, and go into excited state. The frequency of the emitted photon is less than the frequency of the incident photon.
o Anti-Stokes scattering - when the photon receives energy from the molecule. The frequency of the emitted photon is higher than the frequency of the incident photon.
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