Control systems double well potentials

The existence of two stable steady states for the same values of the externally controlled constraints is known as bistability . A mechanical analogy to such a situation is the double well potential shown in Fig. 2. (No potential function is known to exist for open chemical systems that would play the role of the gravitational potential energy in... 

The purpose of this work is to demonstrate that the techniques of quantum control, which were developed originally to study atoms and molecules, can be applied to the solid state. Previous work considered a simple example, the asymmetric double quantum well (ADQW). Results for this system showed that both the wave paeket dynamics and the THz emission can be controlled with simple, experimentally feasible laser pulses. This work extends the previous results to superlattices and chirped superlattices. These systems are considerably more complicated, because their dynamic phase space is much larger. They also have potential applications as solid-state devices, such as ultrafast switches or detectors. 

Since these interfaces are usually constructed of charged detergents a diffuse electrical double layer is produced and the interfacial boundary can be characterized by a surface potential. Consequently, electrostatic as well as hydrophilic and hydrophobic interactions of the interfacial system can be designed. In this report we will review our achievements in organizing photosensitized electron transfer reactions in different microenvironments such as bilayer membranes and water-in-oil microemulsions.In addition, a novel solid-liquid interface, provided by colloidal Si02 particles in an aqueous medium will be discussed as a means of controlling photosensitized electron transfer reactions. 

A fundamental disadvantage of controlled-current techniques is that double-layer charging effects are frequently larger and occur throughout the experiment in such a way that correction for them is not straightforward. Treating data from multicomponent systems and stepwise reactions is also more complicated in controlled-current methods, and the waves observed in E-t transients are usually less well-defined than those of potential sweep i-E curves. 

Adsorption of enteric viruses on mineral surfaces in soil and aquatic environments is well recognized as an important mechanism controlling virus dissemination in natural systems. The adsorption of poliovirus type 1, strain LSc2ab, on oxide surfaces was studied from the standpoint of equilibrium thermodynamics. Mass-action free energies are found to agree with potentials evaluated from the DLVO-Lifshitz theory of colloid stability, the sum of electrodynamic van der Waals potentials and electrostatic double-layer interactions. The effects of pH and ionic strength as well as electrokinetic and dielectric properties of system components are developed from the model in the context of virus adsorption in extra-host systems. 

---