Argonne National Laboratory Center for Nanoscale Materials U.S. Department of Energy

Amanda Petford-LongThe CNM has been very busy preparing for and hosting the DOE triennial peer review of the facility. The paper documents were submitted to DOE in February and comprised an overview of the CNM as a facility in addition to research proposals for the individual groups within CNM. The onsite review was held in May, at which we hosted seven members of the external review panel in addition to our DOE program manager.

The review was a busy time for all CNM staff, and although we have yet to receive formal feedback, I believe that we were able to showcase the excellent capabilities and high scientific impact that is being made by our staff and users. During the review, three of our users [Conal Murray (IBM), Ganhua Lu (University of Wisconsin-Milwaukee), and Horia Metiu (University of California, Santa Barbara)] gave highlight oral presentations and on the second day of the review, we held a poster session at which 39 posters were presented, of which 21 were by members of our user community. As always I am extremely grateful to all those members of our user community who gave their time to come and support the CNM at this critical time. The talks were very well received, and the poster session really showed what a vibrant and successful user community we have been able to attract to CNM. I greatly enjoyed being able to talk with some of you about your exciting science projects and about how the CNM staff and capabilities had helped to facilitate this work.

I am also delighted that we have been able to welcome three new staff scientists to the CNM. See Staff News below for details. In addition we have appointed two new CNM Distinguished Postdocs, Esmeralda Yitamben (EMMD) and Jun Zhang (NanoBio), who will be joining us later this year.

In addition to our outstanding scientific staff, the CNM user program benefits greatly from the state-of-the-art facilities that we maintain. A recent success is the establishment, by staff scientist Anirudha Sumant, of a process to synthesize single-walled carbon nanotubes by using our recently installed Atomate CNT CVD system. We anticipate that the tool will be available to CNM users in time for the July Call for Proposals. I am also very pleased to report that the upgrade to the Carbon computer cluster has been completed, and users are already hard at work using the enhanced system. The CNM also recently approved funding for two AJA sputter-deposition tools (one partly funded by DARPA) that will greatly enhance our thin-film deposition capabilities. These capabilities were added in response to requests from users for additional deposition capabilities for thin films. I hope that you will find the articles in this newsletter interesting, and we look forward to welcoming new and current users to the CNM.

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Call for Proposals Deadline: July 9, 2010

The next CNM call-for-proposals deadline is July 9, 2010. The system is now open for submissions. The Center for Nanoscale Materials holds three Calls for Proposals per calendar year - in March, July, and October. We look forward to the possibility of hosting your exciting and innovative nanoscience and nanotechnology projects.

CNM Workshop in Fall 2010

CNM will host a workshop and training course covering applications of Raman microscopy to nanoscience. One day of invited scientific presentations will include nanoscale materials, nanoscale devices, and nanotechnology projects that have been advanced by exploiting, for example, confocal Raman microscopy and tip-enhanced Raman spectroscopy.  The program will also include an additional 1/2 day short course devoted to hands-on demonstrations and training on the CNM Raman instrumentation.  The co-organizers are David Gosztola (CNM, gosztola@anl.gov) and Vic Maroni (CSE, maroni@anl.gov). Check for periodic updates regarding the date, programming, and registration.

CNM Users Meeting in May 2011

The next CNM Users Meeting will be held in conjunction with Argonne Users Week in May 2011. The program will be comprised of keynote and plenary science lectures, scientific focus sessions, facility status updates and tours, poster sessions, a vendor expo, short courses, and a banquet. The Advanced Photon Source and Electron Microscopy Center will also participate in this event.

NSRC Workshop on Theory and Modeling

A two-day workshop focused on the theory, modeling, visualization, and simulation efforts at all five DOE Nanoscale Science Research Centers will take place October 14-15, 2010, near the Center for Integrated Nanotechnologies in New Mexico. The main co-organizer is Gary Grest, and the CNM local co-organizer is Stephen Gray.

User Notes

The CNM Users' Executive Committee acts as the liaison between the CNM user community and CNM management. One example of input you can provide to them at any time is suggestions for future workshops or focus session topics. Any suggestions can also be sent to the CNM User Office.

Acknowledgment of the use of DOE user facilities such as the CNM in scientific publications and technical presentations is critical to their future sustainability. Review the guidance here.

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Monolithic Ultrananocrystalline Diamond AFM Probes

Nanoscale wear is a key limitation of conventional atomic force microscopy (AFM) SiNx or silicon probes resulting in decreased resolution, accuracy, and reproducibility in probe-based imaging, writing, measurement, and nanomanufacturing applications. Users from the University of Wisconsin-Madison, University of Pennsylvania, and Advanced Diamond Technologies Inc., working with the Nanofabrication and Devices Group, demonstrated the first wafer-level fabrication of monolithic ultrananocrystalline diamond (UNCD) probes. The UNCD probes, with <5-nm grain sizes and smooth tips of 30- to 40-nm radii, are obtained through a combination of chemical vapor deposition of UNCD and microfabrication. While SiNx probes exhibit significant nanoscale wear that increases with humidity, UNCD probes show little measurable wear. The results show the potential of UNCD for AFM probes and demonstrate a systematic approach to studying wear at the nanoscale.

J. Liu et al., Small, 6(10), 1140 (2010).

(a,b) Overlaid TEM images of the SiNx and UNCD tips before and after taking over 200 AFM scans and (c) quantitative comparison of the nanoscale wear of SiNx and UNCD tips at two different relative humidity levels.

Scans of SiNx and UNCD tips for AFM

Shaking Up Cancer

Users from Argonne's Materials Science Division and University of Chicago's Pritzker School of Medicine, working collaboratively on a user science project with CNM's Nanobio Interfaces Group, have discovered that nanostructured magnetic materials offer exciting avenues for probing cell mechanics, activating mechanosensitive ion channels, and advancing potential cancer therapies. Their new report describes an approach based on interfacing cells with lithographically defined microdiscs (1-micron diameter, 60 nm thick) that possess a spin-vortex ground state. When an alternating magnetic field is applied, the iron-nickel (permalloy) disc vortices shift, creating an oscillation, which transmits a mechanical force to the cell. They show that the spin-vortex-mediated stimulus creates two dramatic effects: compromised integrity of the cellular membrane and initiation of programmed cell death. While promising results for cancer cell destruction were observed in the laboratory, animal studies and preclinical trials would be several years in the future. (See video clip...)

D.-H. Kim et al., Nature Materials, November 29, 2009 (News & Views Highlight)

magnetic vortex microdiscs

Biofunctionalized magnetic vortex microdiscs for targeted destruction of cancer cells

Block Copolymer Materials for Photovoltaic Applications

An active donor-acceptor layer with highly ordered nanoscale morphology is necessary in developing high-performance organic or hybrid organic-inorganic solar energy devices. Ideally, the effectiveness of internal processes, including exciton generation and separation, and charge carrier migration is optimized in such a system, leading to an efficient conversion of photons to electricity. A user science project using capabilities within the Electronic & Magnetic Materials & Devices Group has rationally designed such a system. The ordered nanoscale morphology consists of self-assembled poly(3-hexylthiophene) (P3HT) donor domains separated by fullerene C60 hydroxide acceptor domains. A P3HT-block-poly(L-lactide) (P3HT-b-PLLA) block copolymer was used as the structure-directing agent. As revealed by AFM, XRD, and emission photoluminescence, a reduction in P3HT domain collapse leads to improved molecular ordering in the plane perpendicular to the substrate and enhanced photoluminescence quenching when paired with fullerene C60 hydroxide electron acceptors.

Botiz et al., Macromolecules, 42, 8211 (2009); Langmuir, 26, 8756 (2010)

AFM of P3HT-b-PLLA films depicting quality of the lamellar self-assembled structure before (a) and after (b-c) selective removal of the PLLA domains.

AFM of PLLA films

Enhancing Catalytic Oxidation Via Computational Nanoscale Modification

A new mechanism for catalytic oxidation by doped oxides has been discovered by using computational findings that were subsequently supported experimentally. Users from the University of California, Santa Barbara, are pursuing a new paradigm in oxide catalysis by searching for local modifications that either weaken the bond of the oxygen atoms in the oxide or activate the O2 molecule adsorbed from the gas phase. For example, a doped oxide Zn1-xTixO (where x < 0.2) was synthesized and found to be an efficient CO oxidation catalyst. Calculations predict that CO is oxidized through a new mechanism in which surface titanium atoms adsorb and activate O2 from the gas, and experiments using gaseous 18O2 confirmed this new mechanism. Another modification strategy is to support very small oxide clusters on a different oxide surface. In the figure, calculations reveal the mechanism for methanol oxidation to formaldehyde by VO3, MoO3, and CrO3 clusters supported on TiO2.

H. Metiu et al., J. Phys. Chem. C, 113, 16083 (2009); J. Catal., 266, 50 (2009).

dehydrogenation pathways in methanol oxidation

Three dehydrogenation pathways in methanol oxidation by VO3, MoO3, or CrO3 supported on TiO2. All mechanisms lead to the formation of a CH2O group that subsequently desorbs as formaldehyde.

 

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Dual SEM/FIB: A Powerful Capability

Imaging, analysis, and control of matter at the nanoscale are routine with the FEI Nova NanoLab dual-beam microscope. This SEM/FIB provides advanced focused ion beam (FIB) lithography and device prototyping. The instrument features a 100-nm resolution specimen stage, 16-bit scan-generator (4.2 gigapixels), and optimized optics for high-resolution lithography. It is also equipped with the Raith Elphy Plus lithography software and pattern generator, which makes “mix-and-match” processing straightforward.

An example of the fabrication complexity achievable with this instrument is shown in the (bottom) figure of a microfluidic mixer. Changes in the width and depth of the segments generate sheathing in the fluid flow. This new type of mixer is designed to achieve full mixing within a few tens of microns of the source, almost an order of magnitude shorter than standard diffusion-based passive mixers. Contact Alexandra Joshi-Imre (imre@anl.gov) or Leo Ocola of the Nanofabrication and Devices Group for more information.

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FIB Patterns

FIB patterns overlaid on pre-defined structures made by e-beam lithography

Microfluidic Mixer

Microfluidic mixer fabricated by using field stitching without registration marks (1 mm long)

We are delighted to announce that Daniel Lopez became Acting Group Leader for the Nanofabrication and Devices Group on May 1, 2010. Daniel has been a member of the NFD Group since June 30, 2008. His research interests are in nano- and micro-electromechanical systems (NEMS/MEMS), spatial light modulators, X-ray manipulation nanomanufacturing, optical communications, and nonlinear dynamics of nanoscale devices.

Daniel Lopez

Derrick Mancini is transitioning to a new position as Deputy Associate Laboratory Director for Facilities Development at the Advanced Photon Source but will remain a member of the Nanofabrication and Devices Group.

Derrick Mancini

Tiffany Santos has joined the EMMD Group as an assistant scientist, transitioning from her position as a postdoc in that group. Her research focuses on the synthesis and characterization of complex oxide heterostructures. Tiffany recently was awarded a prestigious L'Oreal USA Fellowship.

Tiffany Santos

Rich Schaller has joined the Nanophotonics Group as a scientist. His research focuses on optical experimental investigations of the electronic structure of quantum confined semiconductor materials, excitonic energy relaxation and dissipation, exciton fine structure, generation and fate of multiple electron-hole pairs, and charge manipulation.

Rich Schaller

Subramanian Sankaranaryanan has joined the Theory and Modeling Group as an assistant scientist. His research focus is the development of computational models and simulation techniques to address issues in the use of nanoscale oxides as energy materials.

Subramanian Sankaranaryanan

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