Quadruplex CARS micro-spectroscopy

Authors

  • Israel Rocha-Mendoza,

    1. School of Biosciences and School of Physics and Astronomy, Cardiff University, Museum Avenue, Cardiff, United Kingdom
    2. Centro de Investigación Científica y de Educacción Superior de Ensenada, Ensenada, Baja California, Mexico
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  • Paola Borri,

    1. School of Biosciences and School of Physics and Astronomy, Cardiff University, Museum Avenue, Cardiff, United Kingdom
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  • Wolfgang Langbein

    Corresponding author
    • School of Biosciences and School of Physics and Astronomy, Cardiff University, Museum Avenue, Cardiff, United Kingdom
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Correspondence to: Wolfgang Langbein, School of Biosciences and School of Physics and Astronomy, Cardiff University, Museum Avenue, Cardiff CF10 3US, United Kingdom.

E-mail: LangbeinWW@cardiff.ac.uk

Abstract

We demonstrate a technique for simultaneous detection of coherent anti-Stokes Raman scattering (CARS) at four vibrational frequencies, using simple passive optical elements and without spectrally resolved detection. The technique is based on pump and Stokes femtosecond pulses selectively exciting vibrational resonances through spectral focusing. By replicating the pump and Stokes pair into four pairs, each traveling through appropriate glass elements, we simultaneously excite four different vibrational frequencies. The resulting CARS is a periodic train of intensities detected by a single photomultiplier and frequency analyzed to retrieve its Fourier coefficients. We demonstrate detection of methanol and ethanol mixtures in water and quantitative determination of their concentration owing to the improved chemical selectivity of this quadruplex CARS scheme. Copyright © 2012 John Wiley & Sons, Ltd.

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