In search of multipath interference using large molecules.

The superposition principle is fundamental to the quantum description of both light and matter. Recently, a number of experiments have sought to directly test this principle using coherent light, single photons, and nuclear spin states. We extend these experiments to massive particles for the first time.

An atomically thin matter-wave beamsplitter.

Matter-wave interferometry has become an essential tool in studies on the foundations of quantum physics and for precision measurements. Mechanical gratings have played an important role as coherent beamsplitters for atoms, molecules and clusters, because the basic diffraction mechanism is the same for all particles. However, polarizable objects may experience van der Waals shifts when they pass the grating walls, and the undesired dephasing may prevent interferometry with massive objects.

Toward Two-Dimensional All-Carbon Heterostructures via Ion Beam Patterning of Single-Layer Graphene.

Graphene has many claims to fame: it is the thinnest possible membrane, it has unique electronic and excellent mechanical properties, and it provides the perfect model structure for studying materials science at the atomic level. However, for many practical studies and applications the ordered hexagon arrangement of carbon atoms in graphene is not directly suitable. Here, we show that the atoms can be locally either removed or rearranged into a random pattern of polygons using a focused ion beam (FIB).

Spatial modulation of light transmission through a single microcavity by coupling of photosynthetic complex excitations to surface plasmons.

Molecule-plasmon interactions have been shown to have a definite role in light propagation through optical microcavities due to strong coupling between molecular excitations and surface plasmons. This coupling can lead to macroscopic extended coherent states exhibiting increment in temporal and spatial coherency and a large Rabi splitting. Here, we demonstrate spatial modulation of light transmission through a single microcavity patterned on a free-standing Au film, strongly coupled to one of the most efficient energy transfer photosynthetic proteins in nature, photosystem I.

Sculpturing the electron wave function using nanoscale phase masks.

Electron beams are extensively used in lithography, microscopy, material studies and electronic chip inspection. Today, beams are mainly shaped using magnetic or electric forces, enabling only simple shaping tasks such as focusing or scanning. Recently, binary amplitude gratings achieved complex shapes.

Generation of electron Airy beams.

Within the framework of quantum mechanics, a unique particle wave packet exists in the form of the Airy function. Its counterintuitive properties are revealed as it propagates in time or space: the quantum probability wave packet preserves its shape despite dispersion or diffraction and propagates along a parabolic caustic trajectory, even though no force is applied. This does not contradict Newton's laws of motion, because the wave packet centroid propagates along a straight line.

Electrical current switching in single CdSe nanorods.

Electrical current measurements through individually wired colloidal CdSe nanorods exhibit pronounced multistability. This current switching is analogous to the widely observed fluorescence intermittency in similar systems and may be associated with surface charge dynamics. Such association is quantitatively established for the case when the current is bistable, where the probability of the sojourn time t at the high or low current state follows an exponential dependence.

Xe interacting with porous silicon.

Thin films of porous silicon (PS), structurally characterized by HR-SEM, were studied using xenon Temperature Programmed Desorption (TPD) as a probe of its inner pores. Geometric hindrance of the depth desorbing population and multiple wall collisions result in a unique double-peak structure of the TPD curve. Surface-diffusion assisted adsorption mechanism into inner pores at 48 K is proposed as the origin of these unique TPD spectra.

Anomalous temperature dependent transport through single colloidal nanorods strongly coupled to metallic leads.

We report wiring of individual colloidal nanorods (NRs), 30-60 nm long by 3.5-5 nm diameter. Strong electrical coupling is achieved by electron beam induced deposition (EBID) of metallic lines targeting NR tips with nanometric precision.

Gas sensor based on metal-insulator transition in VO2 nanowire thermistor.

Using temperature driven sharp metal-insulator phase transition in single crystal VO(2) nanowires, the realization of a novel gas sensing concept has been tested. Varying the temperature of the nanowire close to the transition edge, the conductance of the nanowire becomes extremely responsive to the tiny changes in molecular composition, pressure, and temperature of the ambient gas environment. This gas sensing analog of the transition edge sensor radiometry used in astrophysics opens new opportunities in gas sensorics.

Demonstration of spatially inhomogeneous vector beams with elliptical symmetry.

We experimentally demonstrate vector beams having an elliptical symmetry of polarization, breaking the cylindrical symmetry of vector beams (e.g., radially polarized beams).

Dissociation of water buried under ice on Pt(111).

Water on Pt(111) is generally thought to be nondissociative. However, by adsorbing a thick ice film [>150 monolayers (ML)], substantial (approximately 0.16 to 1 ML) dissociation of the "buried water" occurs for T>151 K.

Encoding morphology in oxide nanostructures during their growth.

Programmable control over the overall structure of SnO(2) nanowires grown by vapor-solid synthesis is shown to be possible by pulse modulating the flow rate of the carrier gas in which oxygen (one of the reactants) is entrained. The control is shown to depend on the local oscillation of the supersaturation condition for the SnO vapor (another reactant) in the vicinity of the growing nanostructure. The latter triggers dramatic, reproducible oscillations in the lateral dimensions of the nanostructure and in the direction of its growth.

Landing of size-selected Agn+ clusters on single crystal TiO2 (110)-(1x1) surfaces at room temperature.

Mass-selected Ag(n) (+) (n=1,2,3) clusters with impact energy less than 2 eV per atom were deposited from the gas phase onto rutile titania (110)-(1x1) single crystal surfaces at room temperature and imaged using ultra-high vacuum scanning tunneling microscopy. Upon reaching the surface, Ag monomers sintered to form three-dimensional islands of approximately 50 atoms in size, with an average measured height of 7.5 A and diameter of 42 A.