Orbital Hybridization of OLED Triplet Emitters
High efficiency organic light emitters are a key technology for solid state lighting and display applications. New classes of light emitting molecules, so-called triplet emitters, potentially convert close to 100% of the electrically generated excitons into light. Pt(II) complexes, in particular, have a planar configuration with a directional interaction that can overcome quenching processes at high loading in an OLED. When deposited on Au(111), these molecules arrange in well-defined patterns that allow their analysis by scanning probe microscopy and spectroscopy with submolecular resolution. The measurements, combined with density functional theory, demonstrate that while the ligands only very weakly interact with the substrate, the Pt atoms exhibit charge transfer to the substrate and local hybridization, offering new pathways to study and alter their electronic and thereby optical properties.
SPM by CreaTec.
Pascal R. Ewen, Jan Sanning, Nikos L. Doltsinis, Matteo Mauro, Cristian A. Strassert, Daniel Wegner, Unraveling Orbital Hybridization of Triplet Emitters at the Metal-Organic Interface, PRL 111, 267401 (2013).
Yb lattice clock project
In recent decades the accuracy of optical clocks is advancing by nearly a factor of 1000 every ten years, allowing explorations in frontier physics, such as whether certain fundamental constants are really constant. The clock capabilities already go well beyond those used in very long baseline interferometry (VLBI) or the global positioning systems (GPS). In atomic clocks, ensembles of cold atoms are suspended in magneto-optical traps inside a vacuum to minimize their interaction with the environment. The new optical lattice clocks will be used in ground stations for future space-clock to ground-clock timing comparisons, which should shed new information about underlying physics.
One approach for an atomic clock is based on an the (6s2) 1S0 — (6s6p) 3P0 transition of 171Yb. The figure here shows the spatial distribution of Yb atoms inside a magneto-optical trap. About 2 million atoms can be trapped in a cloud approximately 1 mm in diameter and temperatures below 400 micro-K have been measured. This is the first step in the construction of today's complex atomic clocks.
High efficiency TUBO mini source with narrow beam collimation by CreaTec.