Single-molecule study of the electronic couplings in a circular array of molecules: light-harvesting-2 complex from Rhodospirillum molischianum

Applying single-molecule spectroscopic techniques allowed us to determine the mutual angles between the transition-dipole moments associated with optical transitions of the eight bacteriochlorophyll a molecules which form the so-called B800 ring of the light-harvesting-2 complex from Rhodospirillum molischianum. The orientation of the transition-dipole moment is a sensitive probe for the strength of the local intermolecular interactions because of the well-defined arrangement of the individual molecules within the B800 ring. Our data reveal that the strength of the electronic coupling between individual molecules in the ring is subjected to spatial as well as temporal variations.     

Synergetic activation of "silent receptor" sites leading to a new type of inclusion complex: integration of a 64-membered ring comprising K+ and SO4(2-) ions into a molybdenum oxide-based nanoobject

The new type of inclusion species [Mo(VI)114Mo(V)32O429(H2O)50(KSO4)16]30- comprising 16 encapsulated K+ and SO4(2-) ions shows an unusual 64-membered [K(SO4)]16 ring integrated into a wheel-shaped type nanocluster host; it is formed by a synergetically induced functional complementarity and represents a text-book example of a very complex non-biological material.     

Heavy quarkonia and asymptotic freedom

We use semiclassical methods to discuss the scaling behaviour of quarkonium level splittings up to $\text{M(}\text{Q}\text{Q}\text{) = 200}\text{GeV}$. Special emphasis is laid on the effects of asymptotic freedom which are found to be essential for $\text{M(}\text{Q}\text{Q}\text{) ? 30}\text{GeV}$. The bound t$\text{t}$ system will almost look like the ? system except that $\text{R = ΔM (}{}^3\text{P}{}_2\text{?}{}^3\text{P}{}_1\text{)/ΔM(}{}^3\text{P}{}_1\text{?}{}^3\text{P}{}_0\text{)}$ is larger than 0.8. In the ? system R will already be close to 0.8.