Visualizing Resonances in the Complex Plane with Vibrational Phase Contrast Coherent Anti-Stokes Raman Scattering(full pdf)
Martin Jurna, Erik T. Garbacik, Jeroen P. Korterik, Jennifer L. Herek, Cees Otto, and Herman L. Offerhaus
vol 82 issue 16 p. 7656-7659 sept 15, 2010
In coherent anti-Stokes Raman scattering (CARS), the emitted signal carries both amplitude and phase information of the molecules in the focal volume. Most CARS experiments ignore the phase component, but its detection allows for two advantages over intensity-only CARS.
First, the pure resonant response can be determined, and the nonresonant background rejected, by extracting the imaginary component of the complex response, enhancing the sensitivity of CARS measurements. Second, selectivity is increased via determination of the phase and amplitude, allowing separation of individual molecular components of a sample even when their vibrational bands overlap.
Here, using vibrational phase contrast CARS (VPC-CARS), we demonstrate enhanced sensitivity in quantitative measurements of ethanol/methanol mixtures and increased selectivity in a heterogeneous mixture of plastics and water. This powerful technique opens a wide range of possibilities for studies of complicated systems where overlapping resonances limit standard methodologies.
This article is shown on the coverpage of Analytical Chemistry vol82 issue 16