title: Visualizing resonances in the complex plane with vibrational phase contrast coherent anti-Stokes Raman scattering.
abstract: 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.
authors: Optical Sciences, MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands.
authors: Martin
authors: M
authors: Jurna
authors: Erik T
authors: ET
authors: Garbacik
authors: Jeroen P
authors: JP
authors: Korterik
authors: Jennifer L
authors: JL
authors: Herek
authors: Cees
authors: C
authors: Otto
authors: Herman L
authors: HL
authors: Offerhaus
mesh_terms: D003196:Computer Graphics; D000431:Ethanol / Q000737:chemistry; D000432:Methanol / Q000737:chemistry; D013059:Spectrum Analysis, Raman / Q000379:methods*; D014732:Vibration; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water; D000431:Ethanol; D000432:Methanol