| Probing organic
transistors
with infrared beams
Silicon-based transistors are well-understood,
basic components of contemporary electronic technology. In
contrast, there is growing need for the development of electronic
devices based on organic polymer materials. Organic field-effect
transistors (FETs) are ideal for special applications that
require large areas, light weight, and structural flexibility.
They also have the advantage of being easy to mass-produce
at very low cost. However, even though this class of devices
is finding a growing number of applications, electronic processes
in organic materials are still not well understood. A group
of researchers from the University of California and the ALS
has succeeded in probing the intrinsic electronic properties
of the charge carriers in organic FETs using infrared spectromicroscopy.
The results of their study could help in the future development
of sensors, large-area displays, and other plastic electronic
components. Full
story.
Publication about this research: Z.Q.
Li, G.M. Wang, N. Sai, D. Moses, M.C. Martin, M. Di Ventra,
A.J. Heeger, and D.N. Basov, "Infrared imaging of the
nanometer-thick accumulation layer in organic field-effect
transistors," Nano Letters 6,
224 (2006).
Contact: Zhiqiang Li, zhiqiang@physics.ucsd.edu
Workshop explores
"pseudo-
single-bunch" operation
On June 28, a one-day workshop was held
at Berkeley Lab to explore the possibility of implementing
a new mode of operation at the ALS that would allow single-bunch
timing experiments to be run simultaneously with normal operations.
Organized by Greg Portmann (Accelerator Physics Group) and
Bob Schoenlein (Materials Sciences Division), the Pseudo Single
Bunch Workshop provided the opportunity to begin assessing
the level of interest and the magnitude of the benefit for
the ALS user community. Attended by a mix of ALS users, beamline
scientists, and accelerator physicists, the workshop's agenda
for the morning session included short talks introducing the
concept, scientific opportunities, and engineering approaches
and challenges, while the afternoon discussions focused on
user requirements and future plans.
Typically, storage-ring light sources
operate with the maximum number of electron bunches possible,
with a gap for ion clearing. At the ALS, this means normally
operating with a train of 276 bunches out of a possible 328,
with the gap sometimes containing a single "camshaft"
electron bunch for time-of-flight experiments. Just four weeks
out of every year are set aside for dedicated two-bunch operation,
in which two bunches orbit the ring on opposite sides. To
provide more flexible operations and substantially increase
the amount of operating time for time-of-flight experimenters,
the pseudo-single-bunch mode of operation was proposed by
Janos Kirz as part of the ALS's strategic planning process.
In this mode, the camshaft electron bunch would be vertically
"kicked" into a different closed orbit. By spatially
separating the light from this bunch from the main bunch train,
the ALS could potentially offer single-bunch operation all
year round.
Schematic of the ALS electron-bunch
train. In the proposed pseudo-single-bunch mode, the camshaft
bunch (red) would be "kicked" into a different
orbit from the rest of the multibunch train (green), allowing
the possibility of running single-bunch timing experiments
during normal-mode operations.
There are a number of different ways
in which the orbit of the camshaft bunch can be shaped depending
on the number, location, and repetition rate of the kicker
magnets. This pseudo-single-bunch idea is quite novel and
has not been tried at any light source so far. To test the
concept, a 1.5-MHz kicker magnet is being designed and built.
If all goes well, it will be installed in the Sector 2 straight
section during the long shutdown scheduled for the end of
this year. The main goal is to study the benefits as well
as any unwanted side effects. If the potential negative impacts
on other beamlines turn out to be small enough, the system
can also be run during user shifts. However, user operation
is not part of the project goals at this initial stage. This
revolutionary project has quite a few challenges, so it will
require strong user support to be successful. More
information is available online.
Contacts: Greg Portmann, GJPortmann@lbl.gov
Robert Schoenlein, RWSchoenlein@lbl.gov
2006 ALS Users'
Meeting: Call for Abstracts
and Meeting Information
 General
information, meeting deadlines, and online registration for
this year's ALS Users' Meeting, to be held at Berkeley Lab
October 9–11, is now available on the Users'
Meeting Web site. The early registration deadline is Friday,
September 15. Information about accommodations
for meeting participants in local hotels is available at the
site.
Abstract Submission.
The deadline for abstract submissions for oral presentations
during the ALS Scientific Highlights session is Tuesday, August
15. Submissions
for the oral presentations and poster sessions, including
the student poster competition, can be entered online.
Workshops. This year,
a record 15 workshops will follow the end of the formal Users'
Meeting program beginning Tuesday afternoon (October 10) and
continuing through Wednesday (October 11). Workshop topics
and respective organizers are as follows:
Advanced Magnetic Spectroscopy
Elke Arenholz and Hendrik Ohldag
Advanced Techniques in Angle-Resolved
Photoemission
Zahid Hussain and Eli Rotenberg
Basic and Advanced Scanning
Transmission X-Ray Microscope Measurements
Tolek Tyliszczak
Doing Research at Synchrotrons:
An Introduction
John Bargar and Andrew Doran
Multicolor Scientific Opportunities
at CIRCE and the ALS
Michael C. Martin and Kevin Wilson
Nonlinear Phenomena in Atoms,
Molecules, and Clusters Studied with FELs
Ali Belkacem and Ernie Glover
Opportunities and Challenges
for Momentum-Resolved Inelastic X-Ray Scattering
Jinghua Guo, M. Zahid Hasan, Zahid Hussain, and Z.-X. Shen
Prospects for Studies of Exotic,
Transient, and Ultradilute Gas-Phase Targets
Nora Berrah and Erwin Poliakoff
Theoretical Perspectives of
Resonant Inelastic Soft X-Ray Scattering
Jinghua Guo
Tomography with Soft and Hard
X Rays at the ALS
Alastair MacDowell and Gerry McDermott
The following workshops are being combined
and will be held in tandem:
Soft X-Ray Resonant Scattering
and Reflectivity
Harald Ade, Jeff Kortright, and Jan Lüning
Structure from Coherent Scattering:
Dynamics and Static Imaging
Chris Jacobsen and Steve Kevan
Joint ALS/Stanford Synchrotron Radiation
Laboratory (SSRL) workshops being held in whole or part at
SSRL:
Electron Dynamics in Spin Systems
Yves Acremann, Peter Fischer, and Andreas Scholl
Joint Macromolecular Crystallography
Workshop: Using the Uni-Puck and Web-Ice at ALS and SSRL
Paul Adams, Aina Cohen, Nicholas Sauter, Michael Soltis,
and Christine Trame
Ultrafast Dynamics on Surfaces
and in Liquids Studied by Soft X Rays
Anders Nilsson and Aaron Lindenberg
New faces at
the ALS: Jim Floyd
and Rick Bloemhard
 Jim
Floyd joined the ALS as interim Environment, Safety, and Health
(ES&H) Manager in May. He comes from Berkeley Lab's Environment,
Health, and Safety (EH&S) Division where he's worked in
a variety of capacities since 1993. Although his immediate
priorities are supporting ALS staff and management in implementing
the recommendations of the Lab's Radiation Safety Committee,
he looks forward to working on the full range of environmental,
health, and safety challenges that confront the division.
Among his goals are better integration of the ES&H office
both with ALS staff and with the EH&S Division, improved
safety communication, and continued development of a useful
model of Integrated Safety Management (ISM) for this large
user facility. His office is in Bldg. 80, Rm. 153 and his
telephone extension is x4499. Please drop by or call if you
have any questions or suggestions.
 Rick
Bloemhard has taken over the lead in ALS Operations following
the June retirement of Jan Pusina. Before coming to the ALS,
Rick worked in the Applied Technology Group (ATG) at the Tri-University
Meson Facility (TRIUMF) in Vancouver, British Columbia. ATG
operates three medium-energy, high-current, compact cyclotrons
for medical radioisotope production. This venture, a collaboration
between TRIUMF and a commercial partner, MDS Nordion, delivers
as many as forty thousand patient doses each week. During
his 21 years at the facility, Rick started as an on-shift
cyclotron operator and later became supervisor of the operator
team. One of his accomplishments was the implementation of
a systematic training program for operators. At the ALS, Rick
will be responsible for supervising operators, setting the
weekly operating schedules and helping coordinate day-to-day
activities at the facility. Rick and his family—his
wife and six- and nine-year old daughters—look forward
to exploring the Bay Area and are eager to hear from ALS colleagues
and users about activities, schools, and, of course, good
restaurants in the area.
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