Wave-induced mixing

If large-scale advection alone was responsible for the transport of air parcels from the tropopause to any location in the middle atmosphere, the calculation of the transit time between these two locations would be straightforward. Air parcels, however, do not maintain their integrity over long time scales, because they are rapidly distorted by wave-induced mixing processes into many smaller-scale components. Therefore, the transit time from any point Pq to point P in the atmosphere cannot... 

Other significant spectral changes are also observed. The total splitting increases from 8.3 cm-1 at B=0 T to 24 cm-1 at 5= 12 T. Moreover, due to the field induced mixings of the wave functions, the radiative allowedness of the transitions from the T substates to the ground state is strongly redistributed. The emission from the lowest B-field disturbed substate 1(B) becomes dominant, while the transitions 11(B) —> 0 and III(B) — 0 lose intensity. This is also displayed in the emission decay time of substate I at 1.5 K, which becomes as short as 12 ps at 12 T, while it amounts to 85 ps at zero-field (see next section). Due to this B-field induced increase of radiative allowedness, it also becomes possible to tune magnetically other important properties like the mechanisms of vibrational deactivation [78-82]. 

In rhombic systems, transitions between rris = + and rtis = — become allowed through wave function mixing. However, a new complication arises, one not previously encountered with half-integer systems. Namely the m = d-l and rtis = — levels are now spht in zero-field. If this separation is larger than the microwave energy 2E > /zv), a transition cannot be induced. This is why so many integer-spin paramagnetic metalloproteins are EPR silent. 

A. R. Bogdan, Y. Prior, and N. Bloembergen. Pressure-induced degenerate frequency resonance in four-wave light mixing. Opt. Lett., 6 82-83 (1981). 

Laser-driven VUV sources are based on third harmonic generation (THG) or 4-wave sum mixing (4-WSM) in nonlinear media. These processes are usually described by the induced macroscopic polarization of the medium when irradiated by intense laser light (Armstrong et al [17]). It is well known that the polarization of a medium in the presence of a monochromatic field E(r,t) = EiE(o)i) can be written as... 

When hyperfine-induced mixing of the fine structure components cannot be neglected, the same procedure as described for pure states at the end of the previous section can be followed to account for the hyperfine structure of perturbed msnd Rydberg states. Choosing the wave functions msnd I, F) [cf. Eqs. (62)-(65)] as basis, the Hamiltonian Hq is... 

DOPPLER NARROWING AND COLLISION-INDUCED ZEEMAN COHERENCE IN FOUR-WAVE LIGHT MIXING... 

During the past year we have replaced the Coherent Model 599-03 by the Coherent Model 599-21. With both dye lasers actively stabilized in frequency, the instrumental resolution could be increased to 1 or 2 MHz. Although the system has not yet operated according to specifications, we have obtained new quantitative data on the linewidth of the central components. It is the purpose of this paper to present these new data. They demonstrate the phenomena of colli-sional narrowing of residual Doppler broadening in four-wave light mixing, as discussed in section 2, and of collision-induced Zeeman coherences, treated in section 3. 

Melting, a major physical event, has small, subtle effects on shock-compression wave profiles. The relatively small volume changes and limited mixed-phase regions result in modest, localized changes in loading wave speed. Consequently, shock-induced melting and freezing remains an area with little data and virtually no information on the influence of solid properties and defects on its kinetics. 

The indicated transition pressure of 15 GPa is in agreement with the published data with shock-wave structure measurements on a 3% silicon-iron alloy, the nominal composition of Silectron. A mixed phase region from 15 to 22.5 GPa appears quite reasonable based on shock pressure-volume data. Thus, the direct measure of magnetization appears to offer a sensitive measure of characteristics of shock-induced, first-order phase transitions involving a change in magnetization. 

Table 1 Coefficients for 7[ (a ) for third harmonic generation (THG), degenerate four wave mixing (DFWM), electric field induced second harmonic generation (ESHG), and Kerr effect in methane at the experimental geometry rcH = 2.052 a.u. A CCSD wavefunction and the t-aug-cc-pVDZ basis were used. (Results given in atomic units, the number in parentheses indicate powers of ten.)...

Optical detection offers the most conventional technique to time-resolve the coherent phonons. It includes four-wave mixing [8], transient reflectivity [9,10] and transmission [7] measurements, as well as second harmonic generation (SHG) [15,32]. Coherent nuclear displacement Q induces a change in the optical properties (e.g., reflectivity R) of the crystal through the refractive index n and the susceptibility y,... 

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