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UltraCOLD ion and electron beams for NANOscience

Final Report Summary - COLDNANO (UltraCOLD ion and electron beams for NANOscience)

COLDNANO (UltraCOLD ion and electron beams for NANOscience), aspires to build novel ion and electron sources with superior performance in terms of brightness, energy spread and minimum achievable spot size. The proposed project intends to develop sources with the best beam quality ever produced and to assess them in some advanced surface science research domains. The novel concept is to create ion and electron sources using advanced laser cooling techniques combined with the particular ionization properties of cold atoms as summarized in Phys. Rev. A 88, 033424 (2013).

Several setups have been developed:

A cesium magneto-optical trap has been first used combined with a pushing-guiding laser beam (European Physical Journal D 68, 4 (2014)). The atoms are then excited by lasers and ionized in order to provide the electron source. The use of Rydberg states as precursor of the electrons is currently under investigation and higher monochromaticity than obtained with standard photoionization method is expected (Phys. Rev. A 95, 043409 (2017)). Specific extraction optics for the electrons has been developed. The source is compact and portable in order to be used for several applications such as Low Energy Electron Microscopy, functionalization of semi-conducting surfaces or high resolution Electron Energy Loss Spectrometry (ANR/DFG HREELM project).
Collaboration with Orsay Physics has allowed the creation of a working Focused Ion Beam (FIB) (cf. Ultramicroscopy 164, 70 (2016)) and ERC proof of Concept LASFIB project intend to realize a working prototype out of it.

Control of time, position and velocity of individual particles are also studied in parallel to the development of Rydberg excitation in an Yb MOT. We also test these ideas in a simpler Cs setup. Such a machine providing ions or electrons on demand would open the way for the “ultimate” resolution in time and space for surface analysis, lithography, microscopy or implantation.

Extension to molecules and especially to molecular anions is underway. This could also be used to produce continuous or pulsed atomic ions by molecular dissociation. We currently study the production of molecular anion beam using charge exchange transfer from Rydberg atoms (New J. Phys. 17 (2015) 045018). Different cooling schemes are under investigations (Sisyphus process Phys Rev A 89 043410 (2014), ro-vibrational cooling J. Phys. B: At. Mol. Opt. Phys. 48 (2015) or bichromatic cooling Phys. Rev. A.93.053423 (2016)). We have also proposed with colleague at CERN a laser cooling method for molecular anion (P.R.L. 114, 213001 (2015)).