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So far Lauren Mason has created 238 blog entries.

Congrats to Margaret Murnane for Receiving an Honorary Doctorate from the University of Limerick

JILA Fellow Margaret Murnane has been awarded an Honorary Doctorate from the University of Limerick this year – her 6th Honorary Doctorate.

“I hadn’t even known I was being considered for it,” Murnane says of the award. Murnane, a native of Ireland, is excited to add another excuse to return to the country. Growing up in the 1960s and 1970s in Ireland, only 10% of high school graduates at that time had the opportunity to attend university. It wasn’t until the 1980s and 1990s that Ireland had the resources to invest in higher education by expanding their university system, later followed by flourishing science research. Murnane grew up very close to the University of Limerick, which became a university in 1980. She is excited to hopefully be attending the awards ceremony in person in August of 2021. When speaking of her future trip, Murnane stated: “It’ll be great to be able to be with family and friends again.”

Murnane’s group at JILA focuses on ultrafast laser and X-ray science. This year Murnane was also awarded the Franklin Medal in Physics for her work. She shared the award with JILA Fellow Dr. Henry Kapteyn.

Congrats to Jianwei (John) Miao for Receiving the 2021 Innovation in Materials Characterization Award from the Materials Research Society

Congratulations to Jianwei (John) Miao for receiving the 2021 Innovation in Materials Characterization Award from the Materials Research Society for pioneering coherent diffractive imaging for a wide range of material systems and atomic electron tomography for determining atomic positions without assuming crystallinity.

Check out John’s MRS talk here.

Beyond Crystallography: Coherent Diffractive Imaging and Atomic Electron Tomography

Over the last century, crystallography has been fundamental to the development of many fields of science. However, many samples in materials science, physics, chemistry, nanoscience, geology, and biology are non-crystalline, and thus their 3D structures are not accessible by crystallography. Miao will present two methods that can go beyond crystallography: coherent diffractive imaging and atomic electron tomography. He will illustrate the basic principle and broad application of coherent diffractive imaging. He will also present atomic electron tomography for 3D structure determination of crystal defects and amorphous materials at the single atomic level.

Century-old problem solved with first-ever 3D atomic imaging of an amorphous solid

Glass, rubber and plastics all belong to a class of matter called amorphous solids. In spite of how common they are in our everyday lives, amorphous solids have long posed a challenge to scientists.

Since the 1910s, scientists have been able to map in 3D the atomic structures of crystals, the other major class of solids, which has led to myriad advances in physics, chemistry, biology, materials science, geology, nanoscience, drug discovery and more. But because amorphous solids aren’t assembled in rigid, repetitive atomic structures, as crystals are, they have defied researchers’ ability to determine their atomic structure with the same level of precision.

Until now, that is.

UCLA-led research published in the journal Nature reports on the first-ever determination of the 3D atomic structure of an amorphous solid — in this case, a material called metallic glass…

STROBE solved a century-old scientific problem: Determining the 3D atomic structure of amorphous solids

Amorphous solids such as glass, plastics and rubber are ubiquitous in our daily life and have broad applications ranging from telecommunications to electronics and solar cells. However, due to the lack of any crystal-like long-range order, the traditional X-ray crystallographic methods for extracting the three-dimensional (3D) atomic arrangement of amorphous solids simply do not work. STROBE advanced atomic electron tomography to determine the 3D atomic positions and chemical species of an amorphous solid for the first time – with a stunning precision of 21 picometer. We found that instead of long-range order characteristic of crystals such as diamond, this amorphous metallic glass had regions of short- and medium-range order. Moreover, although the 3D atomic packing is disordered, some regions connect with each other to form crystal-like networks, which exhibit translational but no orientational order. Looking forward, we anticipate this approach will open the door to determining the 3D atomic coordinates of a wide range of amorphous solids, whose impact on non-crystalline solids may be comparable to the first 3D crystal structure solved by x-ray crystallography over a century ago.

Congrats to Franklin Dollar for Receiving the 2021 Tom Angell Fellowship Award for Outstanding Mentoring from UC Irvine

Awarded annually at the Office of Inclusive Excellence’s Mentoring for Achievement and Excellence event, this fellowship is intended to honor Tom Angell’s contributions as the UCI Graduate Counselor to graduate student wellness and retention. Awards are open to graduate students, faculty, and postdoctoral scholars. Award recipients demonstrate outstanding mentorship by going above and beyond their normal duties to create new opportunities to mentor UCI students.

IMEC CDI/Reflectometry Postdoc

Development of EUV-based coherent diffractive imaging for nanoscale device and interface inspection
Supervisor: Claudia Fleischmann
Co-supervisor: John Petersen

The semiconductor industry relies on quantitative nanoscale imaging to inspect devices and components. This project will develop non-destructive, quantitative coherent diffraction imaging techniques compatible with modern and future semiconductor device architectures.

Motivation: Developing and realizing non-destructive, extreme ultraviolet, coherent diffractive imaging techniques suitable for semiconductor devices, interfaces, and materials.

Type of work: 70% computation, 20% experimental, 10% literature Requirements: coherent imaging, algorithm-based image reconstruction

The semiconductor industry routinely relies on nanoscale imaging methodologies for inspection and characterization of nanoscale features in devices and components. However, many of these metrologies are destructive, compatible with a limited sample set, or provide little or no chemical characterization. Extreme ultraviolet (EUV) coherent diffractive imaging (CDI) is a new approach for nanoscale imaging that utilizes diffraction patterns obtained from an impinging photo beam to reconstruct images of a sample via phase retrieval algorithms and is compatible with
a diverse sample set. CDI is non-destructive and, when performed with EUV light, can yield nanoscale, chemically specific images of transmissive and reflective samples (e.g., thin films/2D materials and device stacks, respectively). Imec’s AttoLab is a state-of-the-art metrology laboratory equipped with bright, coherent, tabletop sources which, working on the high harmonic generation (HHG) principle, emit attosecond pulses of tunable EUV light (56-10.3 nm). These sources will be used for performing CDI experiments in both reflection and transmission geometries, with achievable image resolutions of a few 10’s of nm (lateral) and sub-nm (axial). In addition to standard CDI geometries, this project will explore advanced CDI techniques such as ptychographic CDI and CDI coupled with reflectometry for quantitative chemical imaging with a large field of view. The grand challenge of coherent diffractive inspection is the reconstruction of the image from the diffraction patterns and due to the complexity of this process the main focus of this project will be on algorithm development using multithreading GPU processing and machining learning. Additionally, the immense versatility of the HHG EUV sources enables unexplored imaging modalities such as structured illumination CDI, single pixel detection, and time-resolved CDI with few-nm and few-femtosecond spatiotemporal resolution, each of which comes with a dedicated set of development needs. The results of this work will not only provide a yet-to-be-realized metrology pipeline for the semiconductor industry, but also pave the way for non-destructive, quantitative, nanoscale imaging of semiconductor components and devices, while also informing design strategy for device optimization.

We are seeking an outstanding candidate with enthusiasm for a mix of experimental and computational imaging science, with a PhD degree in physics, applied mathematics, data science, or an equivalent specialisation. The candidate should be able to work in an international environment and good written and oral communication skills in English are a prerequisite. Experience in experimental ultrafast optics, coherent imaging, and phase retrieval techniques is required.

Strategic motivation
Coherent Diffractive Imaging (CDI) using the newly installed EUV sources in the AttoLab is a completely new capability for the imec research programs. As a high-resolution, non-destructive and chemically specific imaging technique, CDI holds the potential to be a game-changer for defect, mask, wafer and device inspection. Under the umbrella of the cross-departmental AttoLab endeavour, impact across imec and into partner collaborations is assured, and the successful candidate will be able to carry out groundbreaking research in an inherently cross-functional team. At present, imec is lacking CDI expertise both on the application side as well as on the fundamental aspects. To excel in this research area, we need an experienced, skilled researcher (postdoc) in this field. The postdoc should fill in the missing knowledge gap, transfer knowledge to imec staff and assist us in boosting this line of research.

Atomic structure of a glass imaged at last

The positions of all the atoms in a sample of a metallic glass have been measured experimentally — fulfilling a decades-old dream for glass scientists, and raising the prospect of fresh insight into the structures of disordered solids. If the chemical element and 3D location of every atom in a material are known, then the material’s physical properties can, in principle at least, be predicted using the laws of physics. The atomic positions of crystals have long-range periodicity, which has enabled the development of powerful methods that combine diffraction experiments with the mathematics of symmetry to determine the precise atomic structure of these materials. Moreover, deviations from periodicity that create defects in crystals can be imaged with sub-ångström resolution. But these methods do not work for glasses, which lack long-range periodicity. Our knowledge of the atomic structure of glasses is therefore limited and acquired indirectly. Writing in Nature, Yang et al.1 report the experimental determination of the 3D positions of all the atoms in a nanometre-scale sample of a metallic glass.

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