Imaging the Interior of a Single Molecule
In the past 20 years, optical experiments have reached single molecule sensitivity and removed ensemble averaging associated with variations in the molecular environment. However, each emitting molecule appears as a beacon of light without internal structure due to the limited spatial resolution. By using a scanning tunneling microscope, it is shown that the interior of a single molecule is optically heterogeneous, displaying a rich structure that reflects the states of the molecule involved in the optical transition. The atomic scale resolution in the optical emission is achieved by taking advantage of using tunneling electrons as the excitation source which is spatially confined to Ångström dimensions. In the case of the magnesium porphine, the light absorbing part of chlorophyll, the optical image is highlighted by light emission concentrated in four lobes, but the center of the molecule appears dim. Such images give a first look into the internal structure of a chromophore that has previously been discussed but not visualized. These results provide a new window to observe the coupling of electron and light in a molecule that forms the basis for dye sensitized solar energy conversion, organic light emission, and photocatalytic chemistry.
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LU12644
Ultracold polar molecules in the lowest rovibrational level are selectively formed via an all-optical method
A rotationally and vibrationally pure sample of ultracold polar molecules was produced by applying three laser pulses to laser-cooled atoms. The first pulse formed weakly bound molecules whereas the second and third pulses transferred them into the lowest rovibrational level through a stimulated Raman transition. The all-optical scheme allowed us to prepare a pure molecular sample within 100 ms, which was two orders shorter than previous methods. Moreover, our results opened a new avenue for producing a pure sample of ultracold molecules from a wide variety of atoms for which laser-cooling is available. The high-repetition rate of the experiment made our method ideal for high-precision spectroscopy. The possible application is the precision measurement of the electron-to-proton mass ratio.
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LT12413
Three-dimensional Atomic Lasers from Optical Lattices
The invention of the first optical lasers more than half a century ago
marked the beginning of our ultimate control over light, leading in turn to an
unprecedented technological revolution. With the more recent realization of
Bose-Einstein condensation in atomic gases, a similar degree of control over
matter waves is being achieved and much effort is currently devoted to
converting this new state of matter into "atom lasers". Researchers are now exploring the possibility of dynamically generating coherent matter waves in strongly correlated bosonic systems in optical lattices. Their starting point is an incoherent Mott insulator, for which they show that expansion of the atoms constituting the insulator inside a suitably tuned lattice leads to the formation of solitonic like condensates with nonzero momenta, i.e., to a realization of an atom laser in an optical lattice. They further show that the condensate momenta can be fully tuned by the optical lattice parameters. This finding opens unimaginable possibilities for scientific and technological applications, and possibly a new generation of matter-wave lasers.
