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Current Directions

The mission of the Electron and Optical Physics Division is to "apply its core physics competence to solve the measurement problems encountered by electronic, magnetic, and optical technologies at the atomic level." By developing innovative instrumentation and techniques, it maintains world-class capabilities for: determining magnetic microstructure; establishing the physical and chemical basis of device fabrication on the atomic scale; producing and characterizing artifacts with atomic-scale quality control; developing physical and applied optics in the 10 nm to 100 nm wavelength range; maintaining the National radiometric standard in the 2 nm to 250 nm wavelength range; and delivering quality measurement, calibration, and secondary standards services in the 2 nm to 250 nm wavelength range.

In performance of this mission, the Electron and Optical Physics Division operates major research facilities, performs measurement and calibration services, and pursues basic research.

• Facilities Operation. The Synchrotron Ultraviolet Radiation Facility (SURF III) supports the optical measurement services and research efforts of the Division, and those of other NIST organizational units and external customers. Dramatic improvements in SURF III performance were attained in 2000, including a record operating energy of 387 MeV, and record injection currents above 500 mA. These compare to SURF II energies and currents of 284 MeV and 300 mA, respectively. The increase in optical power output is best illustrated by mention of an accident that occurred in May 2000, when a beamline window that had seen twenty years’ service on SURF II cracked under thermal stress induced by the higher power levels. Our higher level of performance was attained by systematic improvement of the RF and fuzz power control systems, and by increased logging and automatic control of operational parameters. These have greatly improved the reproducibility of operating conditions, so that, for example, injection of 500 mA is now routine, whereas the 300 mA high current for SURF II could not be obtained with any predictability. In addition, considerable improvements in beam stability have been made, sufficient to justify the establishment of a Fourier-transform spectroscopy beamline.

  The Scanning Electron Microscopy with Polarization Analysis (SEMPA) Facility utilizes spin polarization analysis of secondary electrons to image magnetic structure of surfaces and thin films. It has been used to analyze device structure for many major firms in the data storage industry, to develop standard reference materials for magnetic metrology, and to identify the basic mechanisms of exchange coupling that underpin the performance of giant magnetoresistive (GMR) devices. In 2000, a new high-resolution field emission scanning electron microscope microscope was installed in this facility, to enable studies of magnetic domain structrure at 10 nm spatial resolution.

• Measurement and Calibration Services. The Division's activities in calibration and measurement services are centered around SURF III. We maintain a dedicated spectrometer calibration beamline on BL-2, which mainly supports NASA programs in solar physics and EUV astronomy; during 2000 it provided calibrations of instrumentation destined for the NASA TIMED satellite mission, and also performed stability studies on new photodiodes that are candidate components for space-qualified detector packages. A DUV radiometry facility, operated by the Optical Technology Division, is located on BL-4. This facility incorporates an absolute cryogenic radiometer, the NIST primary standard for detector-based radiometry, which allows for intercomparison the primary source-based standard, SURF III. During 2000, the BL-4 facility established an improved DUV spectral responsivity scale, and performed responsivity and stability measurements on candidate photodiodes for use in 157 nm lithography systems. An EUV optics calibration facility has been in long service on BL-7, used primarily to determine reflectivities of multilayer optics, and for related investigations such as grating efficiencies and film dosimetry. In previous years, up to 200 calibrations/year have been performed at this facility. An upgrade of this facility began in Autumn 2000, with the commissioning of a new large-chamber reflectometer that can accommodate the coming generation of EUV stepper mirrors. This chamber will also facilitate high-throughput calibration of smaller EUV optical components. Our UV and EUV detector transfer standards program uses a dedicated beamline on BL-9 to supply calibrated photodiodes to external customers within the framework of the NIST Calibration Services Program. Its activities in 2000 in this regard are summarized in the Appendix. In addition, BL-9 supports custom measurement work associated with the development of new photodetectors.

• Basic Research. The Division's basic research programs focus on issues that bear on the development of nanoscale metrology. In 2000, the Nanoscale Physics Laboratory began operation of its 2.3 K scanning tunneling microscope and demonstrated atomic resolution in applied magnetic fields of up to 10 Tesla, and experiments on the Kondo effect were initiated. EUV emission from laser-irradiated micron-sized noble-gas droplets was measured, in support of a program of compact EUV source development. The complex growth of manganese on an iron substrate was studied and contrasted to that of chromium to help explain the differing magnetic behavior of the two systems. The origin of the increased coercivity observed in exchanged biased bi-layers was modeled and its temperature dependence was predicted. Theoretical research on coherent matter waves resulted in predictions of soliton and vortex structures in Bose-Einstein condensates that were verified experimentally, and assisted in the development of methods for measuring coherence properties of an "atom laser."