Nonlinear transient spectroscopy

NONLINEAR TRANSIENT SPECTROSCOPY WITH HLTRAHIGH TIME-RESOLHTION USING LIGHT SOURCES WITH CONTROLLED COHERENCE... 

Phase-modulated coherent pulse such as due to self-phase modulation has a common feature with incoherent light in that it has broad band-width whose reciprocal is much shorter than the light duration. It, therefore, is expected to play the same role as incoherent light in some nonlinear transient spectroscopy. This expectation has also been confirmed by preliminary theoretical and experimental study. 

Dr. Rohlfing s research interests include the experimental characterization of transient molecules relevant to combustion processes, linear and nonlinear laser spectroscopies, trace detection of pollutants, molecular beam and mass spectrometric studies of carbon and metal clusters, and vibrational relaxation dynamics. He is the author of approximately 50 peer-reviewed articles, holds membership in the American Chemical Society and the American Physical Society, and is a fellow of the American Association for the Advancement of Science. 

Nonlinear Optical Spectroscopy Related to Exciton Transient Response... 

Figure 3 Folded BOXCARS geometry applied in several transient nonlinear optical spectroscopies. In pump-probe spectroscopy, one of the three beams is blocked and the intensity of one of the incoming beams is monitored as a function of the time delay between the remaining two beams (e.g., beam 3 is blocked and beam 2 is monitored as a function of its delay with respect to beam 1, phase-matching condition would be k2 = ki — ki -I- k2>. Beams 4 and 5 are photon echo signals generated from beams 1 and 2. Beams 6 and 7 can be stimulated photon echo or transient grating signals generated from beams 1,2, and 3. In transient grating two of the beams are time coincident. In coherent anti-Stokes Raman spectroscopy, beams 1 and 3 are time coincident and carry the same frequency the difference between this frequency and that of beam 2 (so-called Stokes beam) matches a vibrational frequency of the system and beam 6 will correspond to the anti-Stokes emission.

Within that issue the priority must be given to the key questions which we have posed (Kenney-Wallace and Jonah, 1982). First, how does the electronic motion couple into the fluctuating dynamical structure of the fluid, and second, how do the intermolecular forces and intrinsic motion of the atomic or molecular liquid respond to the sudden perturbation represented by an intense, transient field of a bare electron It is the second question which was the driving force in focusing our attention on nonlinear optical responses of liquids, via nonlinear laser spectroscopy at femtosecond timescales. 

Traditional optical spectroscopy, such as fluorescence imaging, often gets a substantial boost from nonlinear optics, which, as demonstrated by Fujino and Tahara (Chapter 3), can provide temporal resolution and the ability to detect transient chemical species. 

Heilweil, E. J. and Hochstrasser, R. M. (1985). Nonlinear Spectroscopy and Picosecond Transient Grating Study of Colloidal Gold. J. Chem. Phys. 82 4762-4770. 

E. J. Heilweil R. M. Hochstrasser, Nonlinear spectroscopy and picosecond transient grating study of colloidal gold. /. Chem. Phys. 1985, 82, 179-183. 

Guldi et al. reported a set of two-point amidinium-carboxylate H-bonded Cgo-porphyrin ensembles (8) [62]. NMR, absorption and fluorescence spectroscopy confirmed the formation of 1 1 complex between porphyrin and Ceo- The binding constant deduced from nonlinear least-square analyses of the fluorescence intensity versus concentration of Ceo is 2.1 x 10 in toluene. Transient absorption studies reveals that the singlet excited states of zinc porphyrin in 8b... 

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