Intrinsic epoch

Metals have characteristics that make them desirable for construction, implements, and ornamental uses such as in jewelry. Metals have been so important that the names Chalcolithic, Bronze, and Iron Age have been applied to epochs of history. Metals have an enduring quality. They are solid, durable, and attractive. The first draft of this passage is being written with a pen made of sterling silver (an alloy consisting of 92.5% silver and 7.5% copper). The lure of metals has drawn adventurers to remote places, and they have been the spoils of war. Their intrinsic value is exemplified by the ornaments we wear and the role of metals in monetary systems. 

Figure 18 Schematic of epochs for a chemical reaction in solution. E represents the equilibrium epochs, G-D represents the generative-dissipative epochs, I represents the intrinsic or gas-phase epochs, and R represents the recrossing epoch. Adapted from ref. 215.

We wish to make two points about epochs before going on to a discussion of specific systems. First, the picture that we have presented is one where the reactive trajectories arise out of equilibrium, climb the reaction barrier, and then go on to a product equilibrium state. This picture clearly does not hold for nonequilibrium processes such as the photodissociation systems we have discussed. However, the return of these systems to equilibrium often shows the same intrinsic, dissipative, and equilibrium epochs as in equilibrium reaction systems. Thus, one may be able to identify epochs in photodissociation dynamics as well, as has been already discussed in conjunction with the simulation of ICN photodissociation in rare gas solution. ... 

This hierarchy, which has been also seen in manuscripts [32], illustrates the close relation in the medieval epoch between the intrinsic value of a material and its precise situation in an artistic composition. 

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