Four-wave mixing molecular

Vaccaro P H 1995 Resonant four-wave mixing spectroscopy a new probe for vibrationally-excited species Molecular Dynamics and Spectroscopy by Stimulated Emission Pumping (Advances in Chemistry Series) vol 7, ed H-L Dai and R W Field (Singapore World Scientific) p 1... 

Photon Echo (PE) and Reverse Transient Grating (RTG) measurements of the loss of electronic coherence between the X( 2g+) and B(3FIou+) states of molecular iodine are measured by three pulse four wave mixing (FWM). Two cases are considered, relatively low pressure isolated iodine (1-2 Torr), and iodine at high pressure (>10torr) or in the presence of several hundred Torr of buffer gas. 

Fig. 2. RCS of cyclohexylbenzene. Experimental data a) from pump-probe photoionization in a molecular beam (T 10 K) [2], b) from time-resolved degenerate four-wave mixing in a gas cell (T 305 K).

The superscripts, 1 and c, in Table I identify linear and circular polarised light respectively. Since the nanosecond measurements were dominated by molecular rotation in the dithiolene complexes, degenerate four wave mixing measurement were carried out using 100 ps pulses to measure the electronic contribution directly. 

X lT + E r Xij ki, which refer in their order of appearance to the Cartesian polarization components of the CRS, pump, probe, and Stokes fields in the four-wave mixing process [31]. In transparent and optically inactive media, where the input frequencies are away from any electronic transition frequencies, and only the molecular ground state is populated, the selection rules of both resonant coherent and spontaneous Raman scattering are identical... 

Under the influence of an optical pump, the molecular angular distribution described by Equation 12.4 can be considerably modified. In turn, this results in modification of the X ijkl tensor components. Further, we discuss the influence of a polarized pump beam on third-order nonlinear phenomena such as third harmonic generation (THG) [(described by (-3a),ft>,w,a>) coefficient], electric field induced second harmonic generation (EFISH) [x / kl -2(0, (o, o), 0)] and degenerate four-wave mixing (DFWM) X kl ... 

Early theoretical work on FAD was concerned with the dimer equilibrium geometry and the electronic structure (see for example Refs. [32-36]). Ah initio molecular orbital studies on the structure of formic acid dimer in 1984 agreed very well with the experimental structures as determined by electron diffraction [37]. Due to the importance of the double proton transfer of FAD as a key prototype for multiple proton transfer reactions several theoretical studies have been reviewed in the literature [38]. Rotational constants for formic acid dimer were obtained by high resolution spectroscopy of (DCOOH)2 [39] and by femtosecond degenerate four wave mixing experiments in the gas cell at room temperature and under supersonic jet experiments by Matylisky et al. [40]. 

The discussion of the influence of bimolecular quenching and reabsorption of exciton fluorescence on the decay of the exciton gratings in organic crystals may be found in (26). The microscopic formulation of TG and four-wave-mixing experiments in molecular crystals in terms of polaritons may be found in (27). 

Decola P L, Hochstrasser R M and Trommsdorff H P 1980 Vibrational relaxation in molecular crystals by four-wave mixing naphthalene Chem. Phys. Lett. 72 1-4... 

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