Extracting
the Eliashberg function
by Art Robinson
A multitude of important chemical, physical,
and biological phenomena are driven by violations of the Born-Oppenheimer
approximation (BOA), which decouples electronic from nuclear
motion in quantum calculations of solids. Recent advances
in experimental techniques combined with ever-growing theoretical
capabilities now hold the promise of presenting an unprecedented
picture of these violations. By means of high-resolution angle-resolved
photoemission at the ALS and theoretical calculations, a multi-institutional
collaboration that includes researchers from Oak Ridge National
Laboratory, the University of Tennessee, Stanford University,
and the ALS has obtained the first high-resolution spectroscopic
images of the specific vibrational modes that couple to a
given electronic state. Full
story.
Publication about this research: J. Shi,
S.-J. Tang, B. Wu, P. T. Sprunger, W.L. Yang, V. Brouet, X.J.
Zhou, Z. Hussain, Z.-X. Shen, Z. Zhang, and E.W. Plummer,
"Direct extraction of the Eliashberg function for electron-phonon
coupling: A case study of Be(0101)," Phys. Rev. Lett.
92, 186401 (2004).
Contact: Ward Plummer, eplummer@utk.edu
A new gap-opening
mechanism
in a triple-band metal
by Art Robinson
A "wire" of indium only one
or a few atoms wide grown on a silicon surface comprises an
ideal test laboratory for studying one-dimensional (1D) metals.
A new example comes from a collaboration between researchers
from Yonsei University in Korea, the ALS, and the University
of Oregon, who have discovered that the phase transition from
metal to insulator that occurs at low temperature in indium
wires on the silicon (111) surface involves not only the expected
shift in the electronic structure (band-gap opening) but also
a band restructuring that gives rise to an energy gap in a
second band. Full
story.
Publication about this research: J.R.
Ahn, J.H. Byun, H. Koh, E. Rotenberg, S.D. Kevan, and H.W.
Yeom, "Mechanism of gap opening in a triple-band Peierls
system: In atomic wires on Si," Phys. Rev. Lett.
93, 106401 (2004).
Contact: Han Woong Yeom, yeom@phya.yonsei.ac.kr
International
light sources
Web site launched
 On
February 17, the international light source community launched
the first Web site dedicated to providing the latest news
and information on the world's accelerator-driven light sources
(synchrotrons and free-electron lasers) and the science they
produce. The site, lightsources.org,
was developed and is jointly maintained by the Light Source
Communicators Group, whose members represent light source
facilities in Europe, North America, and Asia. Funding for
the project is provided by science funding agencies of many
nations.
Chu announces
new Berkeley Lab
management team
Berkeley Lab Director Steve Chu has announced
the senior management team he will propose when the Lab and
the University of California present their partnership vision
to the Department of Energy's contract competition panel this
week in Chicago.
Fleming, Alivisatos, and McGraw.
The team includes three new appointments—Physical
Biosciences Division Director Graham Fleming to succeed Pier
Oddone as the Laboratory's Deputy Director; Paul Alivisatos,
Materials Sciences Division Director, to become Associate
Laboratory Director (ALD) for Physical Sciences; and Business
Services Division Director David McGraw, to become ALD for
Operations. They will join three other current scientific
ALDs—Joe Gray (Biosciences), James Siegrist (General
Sciences) and Horst Simon (Computing) on the senior team.
Read Director Chu's memo
announcing the new appointments.
Interdisciplinary
Instrumentation
Colloquium kicks off
 Front-line
science builds on new ideas, but also relies on breakthrough
instrumentation. Many activities in the Berkeley scientific
community are directed towards developing advanced measurement
techniques and instrumentation. Despite very disparate goals,
some of these efforts share common problems and could benefit
from sharing experience and expertise. As a first step in
establishing a forum for information exchange and interdisciplinary
collaboration in instrumentation research and development,
an Interdisciplinary Instrumentation Colloquium is being launched
at Berkeley Lab. The colloquia will be held every second Wednesday
at 4:00 P.M. in Berkeley Lab's Building 50 auditorium.
The initial series of talks will be introductions
for nonexperts. Bill Moses, of Berkeley Lab's Life Sciences
Division, gave the first talk on February 9, entitled "Nuclear
Medical Imaging—Techniques and Challenges." Today's
talk is being given by Adrian Lee, of UC Berkeley and Berkeley
Lab, on "Bolometers and the Big Bang." On March
9, Howard Padmore of the ALS will present "Light Fantastic:
The Science and Instrumentation of the Advanced Light Source."
Participation from ALS users is encouraged, and suggestions
for speakers and topics are welcome. For more information,
see the Instrumentation
Colloquium Web page.
Contact: Howard Padmore, HAPadmore@lbl.gov |
