New Visions in Bandmapping

October 21-22, 2005 - - - - - Bldg 50B, Room 4205

Meeting Agenda

In this workshop, we explore the possibility of determining the band structure of solids on the 10's of nm length scale, with a focus on angle resolved photoemission (ARPES)-based techniques. ARPES is a premier tool for understanding not only the bandstructure of solids but also for probing many-body interactions in complex materials. But until now, the photon spot size has limited ARPES to samples on the order ~100 micron or larger. If nm-scale spatial resolution in ARPES could be achieved, we could construct a unique microscope employing electronic structure as a contrast mechanism. Many classes of materials would be subject to this technique:

• submicron-sized single crystals of novel or hazardous materials that cannot be produced or handled in large quantities
• thin films of complex materials (studied on edge after cleavage)
• phase separated materials
• engineered devices (magnetic, electronic)
• microcrystalline domains of disordered materials

This workshop will bring together photoemission practitioners, crystal growers and theorists who will discuss the possible science that can be achieved with this new 'nanoARPES' technique, as well as the novel photon optics and electron detectors for momentum-resolved electron spectroscopy which will be needed to achieve such an instrument. The aim is to develop the scientific case and the user community for a dedicated endstation at the ALS; status of preliminary measurements at the ALS (see figure below for an example) will be discussed.

Organizers: E. Rotenberg, A. Fedorov, and K. Goldberg

Figure, left: The single-crystal domains of a highly ordered pyrolytic graphite sample imaged using valence band contrast. Hotter colors indicate domains with strong valence band emission to the detector.

Figure, right: A typical valence band acquired at a single point (star on left figure)

New Visions in Bandmapping - Workshop Agenda

Location: Bldg. 50B-Room 4205