Raman echo experiment

Vanden Bout D and Berg M 1995 Ultrafast Raman echo experiments in liquids J. Raman Spectrosc. 26 503-11... 

Muller L J, Vanden Bout D and Berg M 1993 Broadening of vibrational lines by attractive forces ultrafast Raman echo experiments in a CH2l CDCl2 mixture J. Chem. Phys. 99 810-19... 

The concept of the Raman echo extends back to Hartmann in 1968 (27), and a few early experiments were performed on gas-phase electronic (28,29) and vibrational (30) transitions. However, it was the paper by Loring and Mukamel in 1985 that pointed out the importance of the Raman echo for studying condensed-phase vibrational dephasing (26). Initial attempts to perform the Raman echo in liquids failed (31), but technical improvements allowed the first successful Raman echo experiment in a liquid in 1991 (3). 

The intensity that can be used is ultimately limited by self-focusing and self-phase modulation in the sample. An early study concluded that these problems would preclude Raman echo experiments (31), but careful experimental design has pushed these limits back. However, the self-focusing problem remains the primary practical limitation in expanding the application of the Raman echo. 

We have performed Raman echo experiments using synchronously pumped dye lasers, followed by dye amplifiers pumped by a Q-switched Nd YAG laser (Fig. 7). These systems are standard (127-129), but several... 

A similar conclusion comes from the results of Inaba et al. (10,11), who performed a Raman echo experiment on the CN stretch of benzonitrile. They saw no evidence for a slow modulation process in this liquid and, therefore, no evidence for dephasing by density fluctuations. It appears that the importance of density fluctuations is overemphasized by the Schweizer-Chandler theory and that they do not contribute significantly to dephasing in simple liquids. 

III. Raman Echo Experiments High Frequency Vibrational Dephasing... 

We thank Dr. R. Inaba, Prof. K. A. Nelson, and Prof. M. Tasumi for their help to the Raman echo experiments, and Dr. Y. Naitoh and Prof. T.J. Kang for their contribution in constructing the laser system. 

One must use higher order (at least fifth order) techniques if one wishes to resolve the nature of the broadening mechanism. The ability of these higher order techniques to make this distinction is based on the echo phenomena very well known for NMR and mentioned above for D4WM with electronic resonances. The true Raman echo experiment is a time resolved seventh order technique which has recently been reported by Berg et al [126, 127, 128 and 129]. It is thus an 8WM... 

Muller, L.J., Vandenbout, D., Berg, M. (1993). Broadening of vibrational Unes by attractive forces Ultrafast Raman echo experiments in aCHCl3 CDCl3 mixture. J. Chem. Phys. 99 810-819. 

---