| Ultrafast
core-hole induced
dynamics in water
A thorough understanding of the chemical
processes that are initiated when radiation interacts with
aqueous systems is essential for many diverse fields, from
condensed matter physics to medicine to environmental science.
An incoming photon with enough energy to produce a core hole
in a water molecule sets off motions that can affect bonding
configurations, which in turn affect subsequent chemical-reaction
pathways. However, it is a fundamental challenge for the radiation
chemistry community to unravel the early time dynamics of
electronically excited states in water because their short
(femtosecond) time scales are difficult to access directly
with pump - probe measurements. Using a combination of isotope
substitution experiments and molecular dynamics simulations,
researchers from Sweden, Germany, and the U.S. have shown
that the ultrafast (0- to 10-fs) dissociation dynamics of
liquid water can be successfully probed with x-ray emission
spectroscopy. Full
story.
Publication about this research: M. Odelius,
H. Ogasawara, D. Nordlund, O. Fuchs, L. Weinhardt, F. Maier,
E. Umbach, C. Heske, Y. Zubavichus, M. Grunze, J.D. Denlinger,
L.G.M. Pettersson, and A. Nilsson, "Ultrafast core-hole-induced
dynamics in water probed by x-ray emission spectroscopy,"
Phys. Rev. Lett. 94, 227401 (2005).
Contact: Michael Odelius, Michael.Odelius@physto.se
First direct
imaging of swollen
microgel particles
Microgels are soft-material particles
consisting of cross-linked polymer networks, 100 nm to 1 μm
in diameter, dispersed in a continuous medium such as water.
A useful feature of certain types of microgel particles is
that they can swell or shrink with changes in external triggers
such as pH and temperature. Thus microgel particles can act
like "nanosponges" and offer many potential applications
in medicine, environmental science, and industry. Because
microgels are usually employed in their swollen state, in
situ characterization of these particles under such conditions
is desirable for understanding their behavior. However, optical
microscopy is inadequate to this task, being limited in resolution
and by the very small difference in refractive index (i.e.,
contrast) between the swollen particles and the continuous
phase. Now, an international team of researchers from the
U.S. and U.K. have obtained the first images of swollen microgel
particles directly in aqueous solution using x-ray microscopy
at the ALS, which, together with spectroscopic determination
of their chemical state, provides insight into the underlying
swelling mechanism. Full
story.
Publication about this research: S. Fujii,
S.P. Armes, T. Araki, and H. Ade, "Direct imaging and
spectroscopic characterization of stimulus-responsive microgels,"
J. Am. Chem. Soc. 127, 16808 (2005).
Contact: Tohru Araki, TAraki@lbl.gov
Harald
Ade, harald_ade@ncsu.edu
Acting Director's
update:
Budgets, safety, etc.
by Janos Kirz
 There
is much news to report. Surely the most important is the President's
budget, announced earlier this month. As a step toward doubling
the budget supporting basic research in the physical sciences,
it includes an increase of over 16% in the ALS budget for
the next fiscal year, starting October 1. Furthermore it also
includes $3M for the design of the User Support Building,
projecting the start of construction for the fall of 2008.
This building will replace Building 10, which has been found
to be seismically unsafe, and which will be demolished. This
budget is a major improvement over what we all expected (and
feared), and deserves the full support of the ALS user community.
At the same time, there are positive
developments to report regarding the Guest House as well.
Work on preparing the bond issue by which the Guest House
construction will be financed is in high gear, with the expectation
that detailed design on this building will also start in October
of this year with construction to start next year.
In preparation for implementing top-off
operations during 2007, the booster will be upgraded to 1.9
GeV from its current 1.5 GeV rating. This will involve a shutdown
in the fall, starting in mid-October, and extending through
the end of the year. This will replace the traditional spring
shutdown for this year.
The search committee (chaired by Paul
Alivisatos) charged with making recommendations to Berkeley
Lab Director Steve Chu for the next ALS Director has delivered
its report. It is my hope and expectation that my permanent
replacement will be named soon and will be ready to take over
on or about July 1.
While all this is good news, and there
is much to celebrate about the remarkable science that continues
to pour out of research at the ALS, we are also facing challenges.
As mentioned in previous issues of ALSNews, during the fall
there were three incidents where procedures for dealing with
radiation shielding were not appropriately followed. Fortunately
no radiation escaped, but these events called attention to
shortcomings in our safety posture. The Berkeley Lab Radiation
Safety Committee suspended our authorization to deal with
shielding access (except in cases of emergency, and then only
by special permission and under special scrutiny). It appointed
a subcommittee that examined the incidents in detail and drafted
35 recommendations that we are in the process of implementing.
Last month, John Bozek, a longtime ALS
beamline scientist and Deputy Leader of the Scientific Support
Group, left the ALS to begin work at the Linac Coherent Light
Source. This is a wonderful opportunity for John, and we all
wish him well at Stanford. Of course his contributions to
the ALS community—both scientific and personal—are
sorely missed.
Contact: Janos Kirz, JKirz@lbl.gov
UEC Corner: Notes
from the Users'
Executive Committee
by Clemens Heske
 Mark
your calendars: the 2006 ALS Users' Meeting will be held October
9–11, 2006, at Berkeley Lab. It will be organized by
Elke Arenholz (EArenholz@lbl.gov)
and Hendrik Ohldag (HOhldag@lbl.gov).
As in recent years, it will follow the proven format of plenary
talks, hot topics sessions, a town hall meeting, and various
workshops devoted to the scientific areas at the ALS. We are
currently soliciting suggestions for workshop topics—they
could include areas of current activity at the ALS, fields
that will be "hot" a few years down the road, etc.
Workshops on areas of mutual interest can also be conducted
jointly with the Stanford Synchrotron Radiation Laboratory
Users' Meeting. Please send suggestions for workshop topics
to Elke and Hendrik and indicate whether you would be interested
in organizing the workshop. Thank you for your help—the
ALS UEC is looking forward to a productive Users' Meeting
in October!
Contact: Clemens Heske, heske@unlv.nevada.edu
First-year anniversary
for lightsources.org
 The
only Web site to comprehensively feature news, information,
and educational materials about the world's light-source facilities,
lightsources.org,
celebrated the anniversary of its launch on February 17, 2006.
Sponsored by 21 of the world's major light sources, this site
serves as a clearinghouse for information on all the world's
light sources, including synchrotron radiation and free-electron
laser facilities. The site is updated daily.
Other features of particular interest
to users include information about and links to all major
light sources, proposal deadlines, a calendar of upcoming
user meetings and scientific conferences, and job opportunities,
as well as a wealth of "useful links" to resources
of all kinds.
Through the past year, lightsources.org
has grown significantly in content and traffic. More than
150 press releases and over 600 synchrotron-related press
items have been listed on the Web site and distributed to
subscribers—via email and RSS (a Web-based news-feed
format). Web traffic is continually increasing and is now
averaging over 100,000 page views per month.
The site maintains an archive of press
coverage—by member facility, topic, and date. To see
the top synchrotron light-source news from 2005, based on
press coverage, please visit the Top
News page.
A newsflash service offers immediate
updates via email as soon as news relevant to light sources
is released to the public. To subscribe to the lightsources.org
News Flash email list, please visit the Subscribe
to News Flash page.
Contact: Art Robinson, ALRobinson@lbl.gov
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