Zero amplitude extinction

As the pressure increases further, a second HB point (HB2) appears at the extinction point E and shifts toward the other HB HBi) point. An example is shown for 4 atm in Fig. 26.1c. Ignition Ii is no longer oscillatory, because the stationary partially ignited branch becomes locally stable in the vicinity of /i. Time-dependent simulations indicate that the two HB points are supercritical, i.e., self-sustained oscillations die and emerge at these points with zero amplitude. In this case, the first extinction Ei defines again the actual extinction of the system. 

All prefactors in Eq. 2.107 (i.e. g, t,f, Af, and Af") are identical for the pairs of the symmetrically equivalent atoms. Hence, Bragg reflections in which the sums of all Miller indices are odd should have zero structure amplitude and zero intensity in any body-centered crystal structure. In other words, they become extinct or absent, and therefore, could not be observed and are forbidden. 

When the refractive index is real, the real part of each scattering amplitude equals the square of its magnitude, the extinction and elastic-scattering efficiency are identical, and the absorption efficiency is zero. The elastic-scattering ef-... 

In general it is difficult to evaluate two closely overlapping relaxation times unless conditions can be found where the amplitude of one of them is very small or zero. In the present case could in fact be observed with almost no interference by 2 (negligible amplitude) by monitoring the reaction at 420 nm which is close to the isosbestic point of PS and PS. 2 monitored at 470 nm where the extinction coefficiencts of PS and PS2 differ strongly interference by could be minimized by evaluating only the last portion of the relaxation curve. 

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