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Yeda R&D Co. Ltd
Abstract ID: 1190
In coherent non-linear spectroscopy, the sample is probed by measuring processes of energy exchange between photons interacting with the sample. One of the most common non-linear spectroscopy methods...
In coherent non-linear spectroscopy, the sample is probed by measuring processes of energy exchange between photons interacting with the sample. One of the most common non-linear spectroscopy methods is coherent anti-stokes Raman scattering (CARS), a coherent four-wave mixing process involving the generation of a coherent vibration in the probed medium. In CARS, three laser photons, a pump photon (omegap) a probe photon (omegapr) and the Stokes photon (omegas), overlap in the medium under investigation. By non-linear interaction with the molecules a fourth coherent photon (omegaAS) with the anti-Stokes frequency omegaAS>=omegap-omegas+omegapr is generated.
There is a need in the art to facilitate coherent anti-stokes Raman scattering (CARS) spectroscopy and microscopy by providing a novel method and system for producing an exciting signal to induce a CARS process in a medium.
The present invention presents a method and a system design for replacing the laser sources typically used in CARS systems today with a single laser source delivering ultrashort laser pulses of a duration of about 10 femtoseconds (10-15 seconds). Such sources are commercially available at a significantly lower cost than current systems. The ultrashort pulses, which are shorter that the oscillation period of typical molecular vibrations, can drive molecular vibrations over nearly the entire vibrational energy spectrum, including the all-important fingerprint spectral region. Using a frequency-domain pulse shaper to synthesize the exact temporal shape of the pulse, the invention specifies several methods to tailor the laser pulses and to optimise them for specific spectroscopic goals - such as high resolution broadband spectroscopy for identification, excitation of specific modes for detection of species, or more complex pulse shapes for identification of a spectroscopic signal in the presence of strong background signals.
Ultrashort laser pulses lasting only a few femtoseconds, replacing older methods for Raman spectroscopy, achieve high-resolution intracellular and extracellular spectroscopy goals in a cost-effective manner. Spanning the entire vibrational energy range, this technology may also be used to achieve true 'chemical imaging' within cells unstained by fluorescent probes.
This system can be used for CARS measurements spanning the entire vibrational energy range to be applied in: Multiphoton microscopy and spectroscopy in live cells, allowing chemical imaging in cells unstained by fluorescent probes. Flame thermometry and combustion studies, where both the directionality and the higher frequency of the CARS signal can be utilized to overcome the strong background emissions. Please enquire regarding licensing or codevelopment partnerships.
Last Updated May 2015