Information Technology Reference
In-Depth Information
Fig. 3.27 Logic possibilities of molecular systems
- Conversion efficiency of the signal by an individual element should be close to
unity. This means that the reaction of the molecule upon excitation has to be
unambiguous and that the excited molecule must continue to respond unambig-
uously without losing excitation energy through intramolecular dissipation.
- It must be possible to switch over an element by a control stimulus to any
required state.
- During element's transition from one state to another, it must remain in it long
enough for the next control stimulus to be guaranteed to transfer the element to a
new state.
- The state of the element should be readable, i.e., it should be possible to
unambiguously determine its state.
Detailed analysis of these requirements shows that in the case of electronic states
they are not fulfilled, at least in part. In the following it will be shown that when the
configuration of the nuclear core changes the conformational transitions turn out to
be suitable for creating molecular switching elements.
At the same time during the 1980s and 1990s, it was shown that ensembles of
molecules with certain characteristics are promising targets for the development of
devices for handling and storing information, i.e., that chemical media can be used
in computing or storage devices. In fact this was a shift from the ideology of
molecular devices (i.e., systems in which individual molecules serve as basic
elements) to the devices built on the basis of chemical environments, i.e., macro-
objects, preserving at the same time certain advantages of molecular objects. These
two major trends (using molecular media and synthesis of large switching mole-
cules) resulted in the second half of the 1990s in the establishment of molecular
information processing devices.
