Non-molecular phases

A situation that arises from the intramolecular dynamics of A and completely distinct from apparent non-RRKM behaviour is intrinsic non-RRKM behaviour [9], By this, it is meant that A has a non-random P(t) even if the internal vibrational states of A are prepared randomly. This situation arises when transitions between individual molecular vibrational/rotational states are slower than transitions leading to products. As a result, the vibrational states do not have equal dissociation probabilities. In tenns of classical phase space dynamics, slow transitions between the states occur when the reactant phase space is metrically decomposable [13,14] on the timescale of the imimolecular reaction and there is at least one bottleneck [9] in the molecular phase space other than the one defining the transition state. An intrinsic non-RRKM molecule decays non-exponentially with a time-dependent unimolecular rate constant or exponentially with a rate constant different from that of RRKM theory. 

The molecular phase effects are especially important when the system has some type of synnnetry. Nevertheless, the typical treatment of non-adiabatic effects ignores the adiabatic phase, although, as cautioned, this is a problematic step. 

For solid nitrogen five modifications are known that differ in the packing of the N2 molecules. Two of them are stable at normal pressure (transition temperature 35.6 K) the others exists only under high pressure. At pressures around 100 GPa a phase transition with a marked hysteresis takes place, resulting in a non-molecular modification. It presumably corresponds to the a-arsenic type. Electrical conductivity sets in at 140 GPa. 

A summary of our results on the phase diagram of water is shown in Figure 8. We find that the molecular to non-molecular transition in water occurs in the neighborhood of the estimated ZND state of HMX. This transition shows that the detonation of typical energetic materials occurs in the neighborhood of the molecular to non-molecular transition. 

Another characteristic point is the special attention that in intermetallic science, as in several fields of chemistry, needs to be dedicated to the structural aspects and to the description of the phases. The structure of intermetallic alloys in their different states, liquid, amorphous (glassy), quasi-crystalline and fully, three-dimensionally (3D) periodic crystalline are closely related to the different properties shown by these substances. Two chapters are therefore dedicated to selected aspects of intermetallic structural chemistry. Particular attention is dedicated to the solid state, in which a very large variety of properties and structures can be found. Solid intermetallic phases, generally non-molecular by nature, are characterized by their 3D crystal (or quasicrystal) structure. A great many crystal structures (often complex or very complex) have been elucidated, and intermetallic crystallochemistry is a fundamental topic of reference. A great number of papers have been published containing results obtained by powder and single crystal X-ray diffractometry and by neutron and electron diffraction methods. A characteristic nomenclature and several symbols and representations have been developed for the description, classification and identification of these phases. 

As a starting point in the description of the solid intermetallic phases it is useful to recall that their identification and classification requires information about their chemical composition and structure. To be consistent with other fields of descriptive chemistry, this information should be included in specific chemical and structural formulae built up according to well-defined rules. This task, however, in the specific domain of the intermetallic phases, or more generally in the area of solid-state chemistry, is much more complicated than for other chemical compounds. This complexity is related both to the chemical characteristics (formation of variable composition phases) and to the structural properties, since the intermetallic compounds are generally non-molecular in nature, while the conventional chemical symbolism has been mainly developed for the representation of molecular units. As a consequence there is no complete, or generally accepted, method of representing the formulae of intermetallic compounds. 

Temperature-programmed vacuum pyrolysis in combination with time-resolved soft ionization mass spectrometry allows principally to distinguish between two devolatilization steps of coal which are related to the mobile and non-mobile phase, respectively. The mass spectrometric detection of almost exclusively molecular ions of the thermally extracted or degraded coal products enables one to study the change of molecular weight distribution as a function of devolatilization temperature. Moreover, major coal components can be identified which are released at distinct temperature intervals. 

Groundwater contamination The mixing of a contaminant with a non-contaminant phase. The mixing is due to the distribution of flow paths, tortuosity of flow paths, and molecular diffusion. 

The most lipophilic TA are benztropine (log P 4.27) (Fig. 1) and bemesetron (log P 4.19) (Fig. 1), possessing either two non-substituted phenyl rings (benztropine) or one dichlorinated phenyl ring (bemesetron). In contrast, the most hydrophilic compounds are QTA due to the presence of the permanent positive charge. However, as determination of Kow requires non-ionized molecular species, calculated log P values might be inaccurate for QTA but surely demonstrate the weak tendency of these substances to be transferred into an organic non-polar phase (Table 1). 

The IPC theory [10] gives a clear and easy rationalization of analyte retention dependence on the presence of ILs used as additives in the mobile phase in low concentrations. In this case, their specific properties as non-molecular polar solvents are not important. In fact, they are salts characterized by a dual nature because of the different properties of the cation and anion. Both contribute to solute retention and... 

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