Coherence spectroscopy

Figure Al.6.16. Diagram showing the directionality of the signal in coherent spectroscopy. Associated with the carrier frequency of each interaction with the light is a wavevector, k. The output signal in coherent spectroscopies is detemiined from the direction of each of the input signals via momentum conservation (after [48a]).

Champion P M, Rosea F, Chang W, Kumar A, Christian J and Demidov A 1998 Femtosecond coherence spectroscopy of heme proteins XVith int. Conf on Raman Spectroscopy ed A M Heyns (New York Wley) pp 73-6... 

Zhu L, Li P, Huang M, Sage J T and Champion P M 1994 Real time observation of low frequency heme protein vibrations using femtosecond coherence spectroscopy Phys. Rev. Lett. 72 301-4... 

References 29-33 introduce the notion of coherence spectroscopy in the context of two-pathway excitation coherent control. Within the energy domain, two-pathway approach to coherent control [25, 34—36], a material system is simultaneously subjected to two laser fields of equal energy and controllable relative phase, to produce a degenerate continuum state in which the relative phase of the laser fields is imprinted. The probability of the continuum state to evolve into a given product, labeled S, is readily shown (vide infra) to vary sinusoidally with the relative phase of the two laser fields < ),... 

Equation (65) illustrates that in the limit of ultrashort pulses the two-pathway method loses its value as a coherence spectroscopy 8s is fixed at it/2 irrespective of the system parameters. From the physical perspective, when the excitation is much shorter than the system time scales, the channel phase carries no imprint of the system dynamics since the interaction time does not suffice to observe dynamical processes. 

We began our analysis in Section II and ended it in Section VC2 by making the connection of the time- and energy-domain approaches to both coherence spectroscopy and coherent control. It is appropriate to remark in closing that new experimental approaches that combine time- and energy-domain techniques are currently being developed to provide new insights into the channel phase problem. We expect that these will open further avenues for future research. 

S. Ramakrishna and T. Seideman, Coherence spectroscopy in dissipative media a Liouville space approach, J. Chem. Phys. 122, 084502 (2005). 

Breit-Wigner phase, two-pathway excitation, coherence spectroscopy energy domain, 180-182 low-lying resonance, continuum excitation, 169-170... 

Coarse-grained approaches, multiparticle collision dynamics, 90-92 Coarse velocity, linear thermodynamics, regression theorem, 18-20 Coherence spectroscopy, two-pathway excitation ... 

Continuum excitation, coherence spectroscopy isolated resonance ... 

Damping effects, transition state trajectory deterministic driving, 209-213 stochastically moving manifolds, 215-222 De Broglie wavelength, two-pathway excitation, coherence spectroscopy 165-166 Decoherence, two-pathway excitation, coherence spectroscopy ... 

Dipole matrix elements, one- vs. three-photon excitation, coherence spectroscopy, 163—166... 

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