- Modeling of Organic Reaction Mechanisms
- Modeling Self-Assembly
- IBM Research Almaden ARC ANGELS Student Seminar Series
Dr. Spike Narayan
Science & Technology
"Mind, like a parachute, works best when open"
"Any sufficiently advanced technology is indistinguishable from magic."
- Arthur C. Clarke
"If we knew what it was we were doing, it would not be called research, would it?"
- Albert Einstein
Almaden Institute 2012 : Superconductivity 297K
Science and Technology welcomes researchers from academia and industry to present their work in Almaden's Science Colloquium Series.
Science and Technology staff who are interested in inviting researchers for this series are encouraged to contact Gavin Jones (email@example.com) or Greg Wallraff (firstname.lastname@example.org) to arrange presentations.
Topic: Size Matters: The Importance of Building Things Small
Speaker: Julia R. Greer (California Institute of Technology)
Date: 1/14/2015 Time: 4:00 PM - 5:00 PM
Location: Auditorium A
Abstract: Professor Greer’s research group develops new ways to synthesize nanostructured metamaterials via cellular architectures and hierarchical design principles. They focus on the internal critical microstructural length scale of materials in studying mechanisms governing mechanical deformation, where competing material, and structure, induced size effects drive overall properties. Many of those materials have micro-lattice and micro-truss architectures with the potential to scale up their desirable nanoscale properties. Their synthetic schemes extend to a wide range of material classes, including metals, ceramics, and semiconductors.
Her lab’s specialized tool - a miniature probe that manipulates and deforms tiny material samples inside a monitoring scanning electron microscope - documents nanomaterial response to mechanical perturbation at different temperatures and deformation rates. By decoupling properties like strength and density a variety of applications are enabled, from ultra-lightweight batteries to damage-tolerant cellular solids and artificial cell scaffolds.
Professor Greer's Ted Talk:
Another specialized tool in Professor Greer's life is the piano. She is an accomplished concert pianist and might be coaxed into performing in the auditorium following her talk.
Topic: Using High-throughput Computation to Design Next-generation Batteries and the Materials Project Electronic Structure Database
Speaker: Anubhav Jain (LBL)
Date: 2/6/2015 Time: 10:30 AM - 11:30 AM
Abstract: It has now been demonstrated that density functional theory (DFT) calculations can be used to design new materials in several technological areas from first principles. This talk will cover two main efforts: (i) the application DFT calculations towards the design of new materials for next-generation Li ion and multivalent ion batteries and (ii) the Materials Project, an open public database of computed materials properties that includes over 60,000 materials entries and represents over 40 million CPU-hours of computation at the NERSC supercomputing center.
The first part of this talk will concentrate on our high-throughput efforts to discover new cathode materials for Li ion batteries, including a description of over 20,000 materials screened computationally, experimental "hits", and new statistical rules regarding battery design. I will also talk about recent efforts in the multivalent aren, in which cations like Mg2+ and Ca2+ are used instead of Li to transfer additional charge and potentially make possible the use of energy dense metal anodes.
The second part of this talk will focus on the Materials Project (MP), a multi-institution effort to compute the fundamental properties of all known inorganic materials and beyond. Currently, the MP web site has registered almost 10,000 users (including ~15% from industry) and includes data on over 60,000 compounds. This dataset also includes almost 30,000 band structures and over 1000 full elastic tensors (to our knowledge, the largest such data set). I will discuss the fundamental software infrastructure that makes this effort possible as well as real use cases by the community. Finally, I will discuss upcoming developments such as user data contribution and the possibility to suggest new compounds for computation.
Topic: Understanding the Optoelectronic Properties of Organic Semiconductors from First-Principles
Speaker: Sahar Sharifzadeh (Boston University)
Date: 4/24/2015 Time: 10:30 AM - 11:30 AM
Location: Auditorium B
Abstract: Organic semiconductors are a highly tunable class of optically active materials that are promising as components in next-generation electronics and optoelectronics; in particular, organic, hybrid, and dye-sensitized solar cells; organic light-emitting diodes (LEDs); thin film transistors; and sensors. Design of these materials relies on building the physical intuition that connects chemistry and solid-state morphology to their functional properties. Here, I will present recent computational studies, based on first-principles density functional theory and many-body perturbation theory, aimed at understanding and tuning the spectroscopic properties of select organic crystalline semiconductors. For both gas-phase molecules and condensed-phase crystals, our quantitative calculations agree well with transport gaps extracted from photoemission spectroscopy and conductance measurements, as well as with measured polarization-dependent optical absorption spectra. Introducing a new analysis of the electron-hole correlation function, we elucidate the nature of low-lying solid-state singlet and triplet optical excitations (excitons). Collectively, this work reveals new ways in which the nature of the exciton can be controlled through solid-state morphology or change of conjugation length, enabling the deliberate design of novel functional organic materials. Lastly, I will briefly describe how I plan to extend these techniques to study charge-transfer at polymer-metal interfaces.
Topic: Resonant Soft X-ray Scattering for Soft Materials
Speaker: Cheng Wang (LBNL)
Date: 5/15/2015 Time: 10:30 AM - 11:30 AM
Location: Auditorium A
Abstract: To meet the challenge of investigating new and complex materials that is relevant to mesoscale energy science, it is essential to connect microscopic dynamical processes to activated kinetic processes and macroscopic function in diverse soft and hard materials. We need sharper tools in order to discover, understand, and control mesoscale phenomena and architectures. Over the past a few years, we have developed Resonant Soft X-ray Scattering (RSoXS) and constructed the first dedicated resonant soft x-ray scattering beamline at the Advanced Light Source, LBNL. RSoXS combines soft x-ray spectroscopy with x-ray scattering thus offers statistical information for 3D chemical morphology over a large length scale range from nanometers to micrometers. Using RSoXS to characterize multi-length scale soft materials with heterogenous chemical structures, we have demonstrated that soft x-ray scattering is a unique complementary technique to conventional hard x-ray and neutron scattering. Its unique chemical sensitivity, large accessible size scale, molecular bond orientation sensitivity with polarized x-rays and high coherence have shown great potential for chemical/morphological structure characterization for many classes of materials. Some recent development of in-situ soft x-ray scattering with in-vacuum sample environment will be discussed. In order to study sciences in naturally occurring conditions, we need to overcome the sample limitations set by the low penetration depth of soft x-rays and requirement of high vacuum. Adapting to the evolving environmental cell designs utilized increasingly in the Electron Microscopy community, customized designed liquid/gas environmental cells will enable soft x-ray scattering experiments on biological, electro-chemical, self-assembly, and hierarchical functional systems in both static and dynamic fashion. Recent RSoXS results on organic electronics, block copolymer thin films, and membrane structure will be presented.
Topic: Continuous Liquid Interface Production (CLIP) of 3D Objects
Speaker: John Tumbleston (Carbon3D)
Date: 5/29/2015 Time: 10:00 AM - 11:00 AM
Location: Auditorium B
Abstract: Recently, the core technology of Silicon Valley start-up, Carbon3D, was unveiled in a simultaneous presentation at TED and publication in Science magazine. This additive manufacturing technology, known as CLIP, allows for complex, functional 3D objects to be fabricated in a continual process. Advantages to a continual process are three-fold: i) parts can be fabricated 25 to 100 times faster than with conventional 3D printers, ii) monolithic parts are produced with internal uniformity and integrity, and iii) the comparatively gentle nature of the process lends itself to producing both delicate structures and parts with unconventional materials. This presentation will detail specifics of CLIP, such as the relationships between critical process-control parameters, along with opportunities for fundamental research and new applications.
Topic: Towards Using NMR fingerprints in Factory Process Environments: Wine, Bombs, Tomatoes and Cryoluminescence
Speaker: Matthew P. Augustine (Department of Chemistry, UC Davis)
Date: 6/5/2015 Time: 10:30 AM - 11:30 AM
Location: Auditorium B
Abstract: The combination of low resolution spectral measurements with modern statistical analysis enables the study complex samples in factory process environments. In this mode, spectroscopy is not used as a tool to understand unknown chemical structures. Here the samples are identical unless problematic. In this case as long as a measurable spectroscopic signature can be found that correlates with these problems or contaminants, statistical analysis can be used to correlate these signals with the degree of purity of the measured sample. Examples of this approach in full bottle wine analysis, homemade explosives, and large format samples such as 1,000 liters of tomato paste in a metal container will be provided.
Topic: Carbon Nanofiber Nanoelectrode Arrays for Biosensing Applications
Speaker: Jessica Koehne (NASA Ames Research Center)
Date: 7/17/2015 Time: 10:30 AM - 11:30 AM
Abstract: A sensor platform based on vertically aligned carbon nanofibers (CNFs) has been developed. Their inherent nanometer scale, high conductivity, wide potential window, good biocompatibility and well-defined surface chemistry make them ideal candidates as biosensor electrodes. Here, we report two studies using vertically aligned CNF nanoelectrodes for biomedical applications. First, CNFs are patterned and grown on silicon devices for cardiac health monitoring. The presence of cardiac reactive protein, cardiac troponin-I and myoglobin are detected simultaneously on one device using typical voltammetry techniques. Second, an implantable device comprised of CNF arrays are investigated as neural stimulation and neurotransmitter recording electrodes for application in deep brain stimulation (DBS). Polypyrrole coated CNF nanoelectrodes have shown great promise as stimulating electrodes due to their large surface area, low impedance, biocompatibility and capacity for highly localized stimulation. CNFs embedded in SiO2 have been used as sensing electrodes for neurotransmitter detection. Our approach combines a multiplexed CNF electrode chip, developed at NASA Ames Research Center, with the Wireless Instantaneous Neurotransmitter Concentration Sensor (WINCS) system, developed at the Mayo Clinic. Preliminary results indicate that the CNF nanoelectrode arrays are easily integrated with WINCS for neurotransmitter detection in a multiplexed array format. In the future, combining CNF based stimulating and recording electrodes with WINCS may lay the foundation for an implantable “smart” therapeutic system that utilizes neurochemical feedback control while likely resulting in increased DBS application in various neuropsychiatric disorders. In total, our goal is to take advantage of the nanostructure of CNF arrays for biosensing studies requiring ultrahigh sensitivity, high-degree of miniaturization, and selective biofunctionalization.
Topic: Block Copolymer-based Materials Development for Sub-20 nm Pitch Patterning Application
Speaker: Ankit Vora (IBM Research - Almaden)
Date: 8/7/2015 Time: 10:30 AM - 11:30 AM
Location: Auditorium B
Abstract: Directed self-assembly (DSA) of block copolymers (BCP) is a promising candidate for extending the patterning capability of optical lithography. While PS-b-PMMA is the most widely used block copolymer for DSA, the minimum half-pitch of this BCP is limited to ~10nm because of the low interaction parameter (chi) between PS and PMMA blocks. Higher-chi BCPs (e.g. PS-b-PEO, PS-b-P2VP, PS-b-PTMSS, etc.) capable of smaller natural period, the Lo, are expected to be necessary for patterning for sub-10nm IC (integrated circuit) devices. But due to the increased mismatch in the surface energies of the two blocks of high-chi BCP, only the lower surface energy block is present at the polymer-air interface, rendering the thin-film undesirable for lithographic applications. Various orientation control strategies such as solvent vapor annealing and the use of topcoat layers have been employed with high-chi BCPs to generate vertically oriented domains. However, these strategies introduce additional process complexities in the integration of high-chi block copolymers into standard lithographic processes.
Recently, we have developed a polycarbonate (PC) containing BCP platform with sub-20 nm pitch resolution for DSA application. Some of the challenges and potential solutions towards the synthesis, NMR-based characterization techniques and purification of highly-pure polycarbonate-containing high- BCP platform will be described. Next, the development of neutral underlayers for the newly-developed PC BCPs will be highlighted. To enable perpendicular orientation of the PC-containing BCPs, a new phase-selective, surface active polymer (SAP) additive-based approach was developed. In this talk, the effect of block copolymer chi, block copolymer architecture (diblock v/s triblock), the effect of SAP architecture, composition and loading amounts of the SAP on the self-assembly (SA) of PC containing high-chi BCPs ranging from 12-26 nm pitch will be described. Finally, the results on pattern transfer and DSA of these materials will also be discussed.