Speckle Patterns with Atomic and Molecular de Broglie Waves

Patton, F.; DePonte, Daniel P.; Elliott, Gregory S.; Kevan, S. D.

doi:10.1103/physrevlett.97.013202

Cited by 18 publications

(15 citation statements)

References 26 publications

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“…In our current coherent atom beam measurements, 8 the ion current for the tips in the helium beam is disappointingly small, implying a smaller than desired detection area. The ideal detection area for dynamic atom scattering of order 1 m 2 is three orders of magnitude larger than the ionization cross section reported here as derived from the ion current in Sec.…”

Section: Discussionmentioning

confidence: 99%

“…1,2 Applications that extract the coherent fraction from such beams in one transverse dimension have been carried out, [3][4][5][6] and recent transverse dimensional coherent experiments have been accomplished. 7,8 Spatial filtering renders the coherent flux available in such experiments many orders of magnitude lower than the incoherent flux used in conventional helium scattering experiments. For this reason, these emerging applications motivate the development of detectors with near unit helium atom detection efficiency and adequate spatial resolution to resolve interference fringes of submicron dimension.…”

Section: Introductionmentioning

confidence: 99%

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Current-voltage relation for a field ionizing He beam detector

DePonte

Elliott

Kevan

2009

Journal of Applied Physics

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Emerging interest in utilizing the transverse coherence properties of thermal energy atomic and molecular beams motivates the development of ionization detectors with near unit detection efficiency and adequate spatial resolution to resolve interference fringes of submicron dimension. We demonstrate that a field ionization tip coupled to a charged particle detector meets these requirements. We have systematically studied the current-voltage relationship for field ionization of helium using tungsten tips in diffuse gas and in a supersonic helium beam. For all 16 tips used in this study, the dependence of ion current on voltage for tips of fixed radius was found to differ from that for tips held at constant surface electric field. A scaling analysis is presented to explain this difference. Ion current increased on average to the 2.8 power of voltage for a tip at fixed field and approximately fifth power of voltage for fixed radius for a liquid nitrogen cooled tip in room temperature helium gas. For the helium beam, ion current increased as 2.2 power of voltage with constant surface field. The capture region of the tips was found to be up to 0.1 m 2 for diffuse gas and 0.02 m 2 in the beam. Velocity dependence and orientation of tip to beam were also studied.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Current-voltage relation for a field ionizing He beam detector

DePonte

Elliott

Kevan

2009

Journal of Applied Physics

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“…In fact, the number of helium atoms arriving at the detector is much higher, but the very low efficiency of the present-day electron-bombardment detectors (less than 10 −5 ) makes it appear so low. Several groups are currently exploring the possibility of improving the detector efficiency with various means [35][36][37][38][39][40][41], but so far no breakthrough has occurred. The other crucial issue is thermal drift.…”

Section: Zone-plate Efficiencymentioning

confidence: 99%

Focusing of a neutral helium beam below one micron

et al. 2012

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In 2008 we presented the first images obtained with a new type of matter wave microscope: NEutral Helium Atom MIcroscopy (NEMI). The main features in NEMI are the low energy of the atoms (<0.1 eV) and the fact that they are neutral. This means that fragile and/or insulating samples can be imaged without surface damage and charging effects. The ultimate resolution limit is given by the de Broglie wavelength (about 0.06 nm for a room-temperature beam), but reaching a small focus spot is still a major challenge. The best result previously was about 2 µm. The main result of this paper is the focusing of a helium atom beam to a diameter below 1 µm. A particular challenge for neutral helium microscopy is the optical element for focusing. The most promising option is to manipulate neutral helium via its de Broglie wavelength, which requires optical elements structured to nanometre precision. Here we present an investigation of the helium focusing properties of nanostructured Fresnel zone-plates. Experiments were performed by varying the illuminated area and measuring the corresponding focused spot sizes and focused beam intensities. The results were fitted to a theoretical model. There is a deviation in the efficiency of the larger zone plate, which indicates a distortion in the zone-plate pattern, but nevertheless there is good agreement between model and experiments for the focus size. This together with the demonstration of focusing to below 1 µm is an important step towards nanometre resolution neutral helium microscopy.

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“…Furthermore real atom sources are not perfectly plane waves and they are not perfectly monochromatic. The monochromaticity and spatial coherence of an atom beam are determined by the velocity distribution (wavelength distribution) and extension of the source [16]. The ultimate coherent beam would seem to be a Bose-Einstein condensate (BEC).…”

Section: Introductionmentioning

confidence: 99%

Nanometer-Resolution Mask Lithography with Matter Waves: Near-Field Binary Holography

2019

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Mask-based pattern generation is a crucial step in microchip production. The next-generation extreme-ultraviolet-(EUV) lithography instruments with a wavelength of 13.5 nm is currently under development. In principle, this should allow patterning down to a resolution of a few nanometers in a single exposure. However, there are many technical challenges, including those due to the very high energy of the photons. Lithography with metastable atoms has been suggested as a cost-effective, less-complex alternative to EUV lithography. The great advantage of atom lithography is that the kinetic energy of an atom is much smaller than that of a photon for a given wavelength. However, up till now no method has been available for making masks for atom lithography that can produce arbitrary, high resolution patterns. Here we present a solution to this problem. First, traditional binary holography is extended to near-field binary holography, based on Fresnel diffraction. By this technique, we demonstrate that it is possible to make masks that can generate arbitrary patterns in a plane in the near field (from the mask) with a resolution down to the nanometer range using a state of the art metastable helium source. We compare the flux of this source to that of an established EUV source (ASML, NXE:3100) and show that patterns can potentially be produced at comparable speeds. Finally, we present an extension of the grid-based holography method for a grid of hexagonally shaped subcells. Our method can be used with any beam that can be modeled as a scalar wave, including other matter-wave beams such as helium ions, electrons or acoustic waves.

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Speckle Patterns with Atomic and Molecular de Broglie Waves

Cited by 18 publications

References 26 publications

Current-voltage relation for a field ionizing He beam detector

Current-voltage relation for a field ionizing He beam detector

Focusing of a neutral helium beam below one micron

Nanometer-Resolution Mask Lithography with Matter Waves: Near-Field Binary Holography

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