Direct extraction of Raman line-shapes from congested CARS spectra

Abstract

Direct extraction of Raman line-shapes from congested CARS spectra.Vartiainen, E.M.; Rinia, H.A.; Müller, M.; Bonn, M. Published in: Optics Express DOI:10.1364/OE.14.003622 Link to publication Citation for published version (APA):Vartiainen, E. M., Rinia, H. A., Müller, M., & Bonn, M. (2006). Direct extraction of Raman line-shapes from congested CARS spectra. Optics Express, 14(8), 3622-3630. DOI: 10.1364/OE.14.003622 General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Abstract:We show that Raman line-shapes can be extracted directly from congested coherent anti-Stokes Raman scattering (CARS) spectra, by using a numerical method to retrieve the phase-information hidden in measured CARS spectra. The proposed method utilizes the maximum entropy (ME) model to fit the CARS spectra and to further extract the imaginary part of the Raman susceptibility providing the Raman line-shape similar to the spontaneous Raman scattering spectrum. It circumvents the challenges arising with experimentally determining the real and imaginary parts of the susceptibility independently. Another important advantage of this method is that no a priori information regarding the vibrational resonances is required in the analysis. This permits, for the first time, the quantitative analysis of CARS spectra and microscopy images without any knowledge of e.g. sample composition or Raman response. ©2006 Optical Society of AmericaOCIS codes: (300.6230) Spectroscopy, coherent anti-Stokes Raman scattering; (000.3860) General, mathematical methods in physics.References and links

Chemical Imaging with Frequency Modulation Coherent Anti-Stokes Raman Scattering Microscopy at the Vibrational Fingerprint Region

“…4 In CARS imaging at a single vibrational frequency, the nonresonant background can mislead the interpretation of local chemical structures. 27,28 One method to eliminate the effect of this problematic background is frequency modulation (FM). [13][14][15][16] Since the nonresonant background originates from the electronic response of the sample, its magnitude is insensitive to the vibrational excitation frequency (i.e., Ω in eq 4).…”

Erratum: “Observation of buried water molecules in phospholipid membranes by surface sum-frequency generation spectroscopy” [J. Chem. Phys. 131, 161107 (2009)]

“…2 and the supporting information of Ref. 1, there are certain caveats and boundary conditions that have to be met for the successful application of the maximum entropy method to the analysis of SFG spectra (as opposed, for example, of using the same analysis tool to investigate coherent anti-Stokes Raman scattering spectra 6 ). The recent reports in Refs.…”

Comparison of coherent and spontaneous Raman microspectroscopies for noninvasive detection of single bacterial endospores

“…In many recent applications, the retrieval of Raman spectrum required an additional scanning of the time delay between pump pulses, which extends the acquisition time and diminishes the advantages of CARS spectroscopy as the way for instant access to the molecular ''fingerprint'' spectral information. The alternative approach was first introduced by Vartiainen (21) and was recently applied by Mülle's group (22) to extract information about Raman lines of complex solutions without sacrificing the signal-to-noise ratio. In brief, the maximum entropy method, which is widely used for signal and image analysis of noisy data, is a noniterative method, which, instead of trying to fit Eq.…”

“…The spectra were retrieved by using the maximum entropy method (21,22), and the results were compared with the Raman data for those endospores (2,3).…”