Breathing motions

The panels in the first and last columns in Figure 5.11 correspond to two selected consecutive times at which a wave front originates close to the nucleus, 14.51 and 15.63 fs, while the central column corresponds to a time halfway between these two. In the upper row of Figure 5.11, we show the electron density within 15 Bohr radii from the nucleus its breathing motion is evident At f = 14.51 fs (a) the central part of the wave packet is at the peak of its contraction. At f = 15.09 fs (b) it reaches its maximal expansion. Finally, at f = 15.63 fs (c), it is contracted again. Thus, the relation between the breathing of the electron density at small radii and the ejection of isolated electron density bursts is more subtle than the obvious correspondence between their periodicities. Indeed, the instants at which the wave fronts are born in the vicinity of the nucleus correspond closely to the stages of maximum contraction of the localized part of the metastable wave packet. This evidence supports the idea that the collisional description of the autoionization dynamics of the doubly excited state of helium holds down to the least excited ones. 

However, zeolite-like materials with ultralarge pores such as Cloverite (20 T, 0.6 x 1.32 nm), VPI-5 (18 T, 1.27 nm), AIPO4-8 (14 T, 0.79 x 0.87 nm) were recently synthesized. A comparison between the pore openings of zeolites and the kinetic diameter of guest molecules shows clearly that zeolites can be used for molecular sieving. It should however be stressed that these values are temperature-dependant temperature increases both the flexibility of the guest molecules and the breathing motions of the host zeolite pore mouth and framework. 

Since a hole in a liquid can move about like an ion or other particle, the dynamic state of a hole is specified in the same way that one describes the dynamic state of a material particle. Thus, one must specify three position and three momentum coordinates X, y, zand p c Py Pz- is, however, an extra feature of the motion of a hole that is not possess by material particles. This feature concerns what is called its breathing motion (Fig. 5.20), i.e., the contraction and expansion of the hole as its size... 

Fig. 5.20. The breathing motion of a hole involves its radial expansion.

In interpreting the relaxation behavior of polydisperse systems by means of the tube model, one must consider that renewal of the tube occurs because the chain inside it moves thermally, either by reptation mode, by fluctuation of the tube length in time (breathing motion), or in both ways (13,14). Moreover, the tube wall can be renewed independently of the motion of the chain inside the tube because the segments of the chains of the wall are themselves moving. The relaxation mechanism associated with the renewal of the tube is called constraint release. 

We now compare the vibrational amplitude with EXAFS cjj. Using the totally symmetric stretching mode of FeCH O) " (v = 390cm ) and Fe(H,03 + (v = 523 cm we can calculate the mean square vibrational amplitude of the breathing motion of these complexes with... 

HAL and PAL Proposed Tyr loop-in model for breathing motion tor substrate access The molecular basis of PAL and TAL substrate versatility Hydroxycinnamoyl CoA Shikimate/Quinate Hydroxycinnamoyltransferase Cytochrome P-450 Hydroxylation Reactions (Cinnamate 4-Hydroxylase, p-Coumarate 3-Hydroxylase , and Ferulate 5-Hydroxylase ) Comparison to Bacterial/Mammalian P-450s Subcellular localization of C4H, pC3H , and F5H ... 

HAL and PAL Proposed Tyr loop-in model for breathing motion for substrate access... 

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