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Spectroscopies femtosecondes de molécules biologiques : vers une détection optique des bactéries

Abstract : Within the general framework of the optical detection of bacteria, we implement two original methods to distinguish molecules whose optical properties are similar: femtosecond LIBS for bacteria, and coherent control for flavins.

Coherent control distinction of flavins consists in 400 nm pulse shaping, and then controlling the excited state of molecules in the liquid phase by a second infrared pulse which decreases fluorescence. We bring to the fore solvent role for this two pulses process of depletion with tryptophan. Spectroscopic studies in liquid phase with intense pulses sometimes generate unexpected non-linear effects, which is at the origin of the study of the filamentation in an absorbing liquid medium.

Photofragmentation of ionized biological chromophores, flavins and tryptophan, are examined in gas phase using similar ``pump-pump" scheme to the one used for depletion. We show, with flavin mononucleotide, that the second pulse decreases certain ways of fragmentation to the benefit of the others. Lastly, we reveal the potentialities of femtosecond LIBS for bacteria discrimination and foliar analysis.
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https://tel.archives-ouvertes.fr/tel-00195925
Contributor : Laurent Guyon <>
Submitted on : Tuesday, December 11, 2007 - 4:56:53 PM
Last modification on : Thursday, October 15, 2020 - 9:00:22 AM
Long-term archiving on: : Monday, April 12, 2010 - 6:57:56 AM

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Laurent Guyon. Spectroscopies femtosecondes de molécules biologiques : vers une détection optique des bactéries. Biophysique [physics.bio-ph]. Université Claude Bernard - Lyon I, 2007. Français. ⟨tel-00195925⟩

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