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We here report on the realization of an electrodynamic trap, capable of trapping neutral atoms and molecules in both low-field and high-field seeking states. Confinement in three dimensions is achieved by switching between two electric field configurations that have a saddle point at the center of the trap, i.e., by alternating a focusing and a defocusing force in each direction. The ac trapping of 15ND(3) molecules is experimentally demonstrated, and the stability of the trap is studied as a function of the switching frequency. A 1 mK sample of 15ND(3) molecules in the high-field seeking component of the |J,K=|1,1 level, the ground state of para-ammonia, is trapped in a volume of about 1 mm(3).

Polar molecules in high-field seeking states cannot be trapped in static traps as Maxwell's equations do not allow a maximum of the electric field in free space. It is possible to generate an electric field that has a saddle point by superposing an inhomogeneous electric field to an homogeneous electric field. In such a field, molecules are focused along one direction, while being defocused along the other. By reversing the direction of the inhomogeneous electric field the focusing and defocusing directions are reversed. When the fields are being switched back and forth at the appropriate rate, this leads to a net focusing force in all directions. We describe possible electrode geometries for creating the desired fields and discuss their merits. Trapping of 15 ND 3 ammonia molecules in a cylindrically symmetric ac trap is demonstrated. We present measurements of the spatial distribution of the trapped cloud as a function of the settings of the trap and compare these to both a simple model assuming a linear force and to full three-dimensional simulations of the experiment. With the optimal settings, molecules within a phase-space volume of 270 mm 3 ͑m/s͒ 3 remain trapped. This corresponds to a trap depth of about 5 mK and a trap volume of about 20 mm 3 .

A linear AC trap for polar molecules in high-field seeking states has been devised and implemented, and its characteristics have been investigated both experimentally and theoretically. The trap is loaded with slow 15 ND 3 molecules in their ground state (para-ammonia) from a Stark decelerator. The trap's geometry offers optimal access as well as improved loading. We present measurements of the dependence of the trap's performance on the switching frequency, which exhibit a characteristic structure due to nonlinear resonance effects. The molecules are found to oscillate in the trap under the influence of the trapping forces, which were analyzed using 3D numerical simulations. On the basis of expansion measurements, molecules with a velocity and a position spread of 2.1 m/s and 0.4 mm, respectively, are still accepted by the trap. This corresponds to a temperature of 2.0 mK. From numerical simulations, we find the phase-space volume that can be confined by the trap (the acceptance) to be 50 mm 3 (m/s) 3 .

A four electrode electrostatic trap geometry is demonstrated that can be used to combine a dipole, quadrupole and hexapole field. A cold packet of ¹⁵ ND ₃ molecules is confined in both a purely quadrupolar and hexapolar trapping field and additionally, a dipole field is added to a hexapole field to create either a double-well or a donut-shaped trapping field. The profile of the ¹⁵ ND ₃ packet in each of these four trapping potentials is measured, and the dependence of the well-separation and barrier height of the double-well and donut potential on the hexapole and dipole term are discussed

Pure inversion spectra for the ͉J,K͘ϭ͉1,1͘ level of 14 ND 3 and of 15 ND 3 are recorded at 10 kHz resolution using a molecular-beam microwave-UV double-resonance spectrometer. The observed spectra are fully assigned, and the energies of all ͉J,K͘ϭ͉1,1͘ hyperfine levels of both deuterated ammonia isotopomers are obtained. The shifting and splitting of the manifold of hyperfine levels in external electric fields is calculated and its implications for molecular-beam deceleration and trapping experiments are discussed.

By miniaturizing electrode geometries high electric fields can be produced using modest voltages. A planar array of 20 m wide gold electrodes, spaced 20 m apart, is made on a sapphire substrate. A voltage difference of up to 350 V is applied to adjacent electrodes, generating an electric field that decreases exponentially with distance from the substrate. This microstructured array can be used as a mirror for polar molecules and can be rapidly switched on and off. This is demonstrated by retroreflecting a beam of state-selected ammonia molecules with a forward velocity of about 30 m=s. DOI: 10.1103/PhysRevLett.93.020406 PACS numbers: 03.75.Be, 33.55.Be, 33.80.Ps, 39.10.+j Miniaturizing current carrying structures has proven to be a very successful strategy for atom optics [1,2]. Microfabricated wires on surfaces allow one to exert extremely high magnetic forces on atoms using only moderate currents. A variety of microfabricated atom optical elements such as mirrors [3], guides [4], conveyer belts, and traps [5] have been realized. The integration of many of these devices into one circuit offers novel and exciting possibilities for quantum computation and atom interferometry [6,7].Miniaturizing charge carrying structures to manipulate polar molecules is equally promising. Using microstructured electrodes large electric fields and large field gradients can be generated with only moderate voltages. The interaction of polar molecules with electric fields is orders of magnitude stronger than the interaction of atoms with magnetic fields, and one can easily construct potentials on the order of a Kelvin. This allows one to design microstructured electrodes to manipulate cold polar molecules as produced, for instance, via buffer gas loading [8], Stark deceleration [9], collisions [10], or photoassociation [11]. The rotational and vibrational degrees of freedom as well as the (anisotropic) dipole-dipole interaction of polar molecules offer novel possibilities for interferometry and quantum computation [12].In this Letter, we experimentally demonstrate a microstructured switchable mirror for polar molecules. It is well known that a planar array of equidistant electrodes with a voltage difference between adjacent electrodes produces an electric field that decays exponentially with the distance from the surface. Such an array can therefore be used as an electrostatic mirror for polar molecules in so-called low-field seeking quantum states [13]. The principle of an electrostatic mirror was first discussed by Gordon as a means to select slow molecules [14]. Later this geometry was discussed in much more detail by Opat and co-workers [15,16], who experimentally demonstrated an electrostatic mirror by reflecting a beam of chloromethane (CH 3 Cl) from it at grazing angles of incidence. In the experiments reported here we demonstrate reflection of a cold beam of state-selected polar molecules from a microstructured electrostatic mirror under normal incidence. The mirror consists of an interdigitated structure of 20 m wide gol...

TNO has built EBL2, an EUV exposure facility equipped with an in vacuo X-ray photoelectron spectroscopy setup (XPS) and an in-situ ellipsometer. EBL2 enables lifetime testing of EUV optics, photomasks, pellicles and related components under development in relevant EUV scanner and source conditions, which was previously not available to industry. This lifetime testing can help the industry to prepare for high volume production using EUV lithography by bringing forward information about material behavior which facilitates the development cycle. This paper describes an EUV photomask lifetime test performed at EBL2. The mask was exposed to different EUV doses under a controlled gas and temperature environment. To investigate how EUV light interacts with the mask, various analysis techniques were applied before and after EUV exposure. In-situ XPS was used to investigate elemental compositions of the mask surface. An ex-situ critical dimension scanning electron microscope (CD-SEM) and an atomic force microscope (AFM) were used to explore the impact of EUV light on critical dimensions (CD) and feature profiles. In addition, EUV reflectometry (EUVR) was used to investigate the change of reflectivity after EUV exposures. The exposure conditions are reported, as well as an analysis of the effects observed.