Initial relaxation direction

Infinite-order sudden approximation (IOSA), electron nuclear dynamics (END), molecular systems, 345-349 Initial relaxation direction (IRD), direct molecular dynamics, theoretical background, 359-361 Inorganic compounds, loop construction, photochemical reactions, 481-482 In-phase states ... 

Figure 14 Illustration of the general procedure used to locate the initial relaxation direction (IRD) toward the possible decay products, (a) General photochemical relaxation path leading (via conical intersection decay) to three different final structures, (b) Potential energy surface for a model elliptic conical intersection plotted in the branching plane, (c) Corresponding energy profile (as a function of the angle a) along a circular cross section centered on the conical intersection point and with radius d.

Rather than review the development of hot atom kinetic theory here, the reader is directed to several recent approaches and the references therein (43- 8). While there continues to be debate over the initial relaxation of the hot atom velocity distribution and the conditions imder which a Maxwell-Boltzmann-like temperature profile for reaction can be established, the general dynamical features of at least one very important high energy reaction, F + H2 HF + H, have been described consistent with experimental results. 

In iS Relaxation, the static magnetic field is applied parallel to the initial spin direction (x axis of Fig. 3). Where there are no magnetic interactions, the hf relaxation of Mu and of pseudo- Mu wiU be the only source of spin relaxation, and p spin in any other chemical states wiU not evolve. Where there are electric or nuclear spins that interact with p" spin, the latter will start to evolve at a rate depending on the magnetic field intensity formed by the electric or nuclear spins. The experiments are performed using positron counters placed at the upstream and/or downstream positions of the p" beam (Dj and Dj in Fig. 3). The count rates of the counters, Rj(t) and R ft), are described using Eq. 3 as. 

HDPE, where no p relaxation is observed [29], In these sheets, the crystal lamellae make an acute angle of about 40° with the initial draw direction [30], Applying the stress along the initial draw direction then gives the maximum resolved shear stress parallel to lamellar planes. We see from Figure 10.10 that the maximum loss is tan 3o, confirming that the a relaxation in HDPE is primarily an interlamellar shear process from a macroscopic mechanical viewpoint. 

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