Scientists Create New Kind Of Molecule

[Xamonas Chegwé]

Using lasers and super-low temperatures, scientists have managed to create a type of molecule that has previously only been theoretically possible. Clever gits, ain't they?

http://news.bbc.co.uk/1/hi/sci/tech/8013343.stm

[charlou]

Over seventy years to fruition ... good stuff.

[Beelzebub2]

There is almost identical article here, but with a bit more accurate pictorial representation.

And if anyone's interested in creation of polar and nonpolar ultra-long-range Rydberg molecules - there is a PDF document here.

And here's some Stilton:

[Beelzebub2]

And a related article from Nature:

Observation of ultralong-range Rydberg molecules

[Beelzebub2]

As I can see that everyone is so thrilled about the Rydberg molecules, here comes some more interesting info about the aforementioned molecules.

Rydberg molecule can be classified as Rydberg matter (named after the Swedish physicist Johannes Rydberg). This type of condensed matter is solid or possibly liquid with varying density, from very high to very low density . Life-time and stability of Rydberg matter against recombination and ionization is still debated in some parts of the physics community due to lack of effective methods of study, especially in link with Ultracold Plasma (physics). The most important distinction between a plasma and Rydberg matter is the formation of chemically (metallically) bonded clusters, thus Rydberg matter may appear as a dusty plasma. The clusters of Rydberg matter are small crystals of well-defined form.

Rydberg matter is a metastable state of highly excited atoms or molecules which are condensed in a solid - or liquid-like very low density matter. For example, Cs atoms with main quantum-mechanical level of excitation ~ 10-15 form a Rydberg matter with the density 1017-18 cm-3 which are used in thermionic converters.

Rydberg matter is formed because the condensed state energetically is more favorable compared with the initial system of non-interacting excited atoms. Bonding of excited atoms in the Rydberg matter is due to delocalization of highly excited valence electrons and therefore its nature is similar to that of metals. Exception is that in the Rydberg matter the collective valence electrons are at many orders of magnitude lower average densities compared to ordinary metals. E.g. the Rydberg matter made of Cs atoms with main quantum-mechanical level of excitation 12 has the average equilibrium density of electrons 1.1 1018 cm-3. Additionally the valence electrons are distributed extremely non-uniformly in the Rydberg matter causing a significant delay in the decay of excitations compared non-interacting excited atoms.

Consequently both life-time and stability of Rydberg matter against impurity recombination do increase with the quantum-mechanical level of excitation. E.g. the half-life of Rydberg matter made of Cs atoms with main quantum-mechanical level of excitation 12 is as high as 17 s.

Each Rydberg series of energies converges on an ionization energy threshold associated with a particular ionic core configuration. These quantized Rydberg energy levels can be associated with the quasiclassical Bohr atomic picture. The closer you get to the ionization threshold energy, the higher the principal quantum number, and the smaller the energy difference between near threshold Rydberg states. As the electron is promoted to higher energy levels in a Rydberg series, the spatial excursion of the electron from the ionic core increases and the system is more like the Bohr quasiclassical picture.

The Rydberg states of molecules with low principal quantum numbers can interact with the other excited electronic states of the molecule. This can cause shifts in energy. The assignment of molecular Rydberg states often involves following a Rydberg series from intermediate to high principal quantum numbers. The energy of Rydberg states can be refined by including a correction called the quantum defect in the Rydberg formula. The quantum defect correction can be associated with the presence of a distributed ionic core.

[Beelzebub2]

There has been an interesting study about the behaviour of the Rydberg molecule in a magnetic field.

Here comes the full article in PDF.

Also, a study has been made about the interactions of the Rydberg-molecules with surfaces and adsorbates.

Full article here.


Enjoy, folks.

[charlou]

Cheesy derail moved to here: http://rationalia.com/forum/viewtopic.p ... 949#p64949