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University of Rochester

1. Kamga, François Mkankam (1946 - ). Coherent anti-stokes raman scattering : suppression of the non-resonant background contribution and observation of beats between adiabatic and non-adiabatic contributions.

Degree: PhD, 2017, University of Rochester

The existence of a nonresonant contribution to the Coherent Anti-Stokes Raman Scattering (CARS) is widely cited as the main disadvantage of CARS. This contribution is due to the nonlinear response of the electrons to applied fields (Kerr effect) as well as from other far away from resonance Raman modes. It interferes with resonant signal and leads to distorted lineshape. We have developed a pulse sequenced suppression technique using ultra-short dye laser pulses synchronously pumped and mode locked by an argon ion laser. Unlike normal CARS, part of the pump beam is split, delayed and used as a probe to generate the pulse sequenced CARS signal. All the intermediate transitions responsible for the nonresonant contribution involve virtual states. The delayed generation of the anti-Stokes signal in pulse sequenced CARS assured that virtual intermediate states will all have decayed and only the resonant processes, with real intermediate states, will contribute to CARS generation. The technique was applied to 20% to 5% mixtures of CS₂ in toluene (C₆H₅CH₃) and two orders of magnitude rejection of the nonresonant background contribution were achieved, being only limited by the background energy be tween pulses in our dye laser. It was concluded that NdYAG lasers would be a better pump laser for the technique. A new temporal interference phenomenon was also observed. A beat was observed between the CS₂ oscillator which relax non-adiabatically to their natural frequency, after being excited off-resonance, and the nonresonant oscillators of the bulk-toluene which adiabatically follow the applied fields. This is potentially useful for extracting homogeneous linewidth from an inhomogeneously broadened line.

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Kamga, F. M. (. -. ). (2017). Coherent anti-stokes raman scattering : suppression of the non-resonant background contribution and observation of beats between adiabatic and non-adiabatic contributions. (Doctoral Dissertation). University of Rochester. Retrieved from http://hdl.handle.net/1802/32197

Chicago Manual of Style (16th Edition):

Kamga, François Mkankam (1946 - ). “Coherent anti-stokes raman scattering : suppression of the non-resonant background contribution and observation of beats between adiabatic and non-adiabatic contributions.” 2017. Doctoral Dissertation, University of Rochester. Accessed March 30, 2017. http://hdl.handle.net/1802/32197.

MLA Handbook (7th Edition):

Kamga, François Mkankam (1946 - ). “Coherent anti-stokes raman scattering : suppression of the non-resonant background contribution and observation of beats between adiabatic and non-adiabatic contributions.” 2017. Web. 30 Mar 2017.

Vancouver:

Kamga FM(-). Coherent anti-stokes raman scattering : suppression of the non-resonant background contribution and observation of beats between adiabatic and non-adiabatic contributions. [Internet] [Doctoral dissertation]. University of Rochester; 2017. [cited 2017 Mar 30]. Available from: http://hdl.handle.net/1802/32197.

Council of Science Editors:

Kamga FM(-). Coherent anti-stokes raman scattering : suppression of the non-resonant background contribution and observation of beats between adiabatic and non-adiabatic contributions. [Doctoral Dissertation]. University of Rochester; 2017. Available from: http://hdl.handle.net/1802/32197

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