title: Chemical imaging and microspectroscopy with spectral focusing coherent anti-Stokes Raman scattering.
abstract: We demonstrate two different coherent anti-Stokes Raman scattering (CARS) microscopy and microspectroscopy methods based on the spectral focusing mechanism. The first method uses strongly chirped broadband pulses from a single Ti:sapphire laser and generates CARS signals at the fingerprint region. Fast modulation of the time delay between the pump and Stokes laser pulses coupled with lock-in signal detection significantly reduces the nonresonant background and produces Raman-like CARS signals with a spectral resolution of 20 cm(-1). The second method generates CARS signals in the CH (carbon-hydrogen) stretching region with IR supercontinuum pulses from a photonic crystal fiber. The spectral resolution of 30 cm(-1) is achieved. Maximum entropy method is used to retrieve a Raman-equivalent CARS spectrum from lipid membranes. Chemical imaging and microspectroscopy are demonstrated with various samples.
authors.affiliation: University of Texas at Austin, Department of Chemistry and Biochemistry, 1 University Station A5300, Austin, Texas 78712, USA.
authors.forename: Bi-Chang
authors.initials: BC
authors.lastname: Chen
authors.forename: Jiha
authors.initials: J
authors.lastname: Sung
authors.forename: Xiaoxi
authors.initials: X
authors.lastname: Wu
authors.forename: Sang-Hyun
authors.initials: SH
authors.lastname: Lim
mesh_terms: D001704:Biopolymers / Q000032:analysis*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005227:Fatty Acids / Q000032:analysis*; D008853:Microscopy / Q000295:instrumentation*; D010363:Pattern Recognition, Automated / Q000379:methods*; D013059:Spectrum Analysis, Raman / Q000295:instrumentation*
chemical_list: D001704:Biopolymers; D005227:Fatty Acids