Celebrating 20 years of Advanced Electron Microscopy at SuperSTEM
The 13th of December 2022 marks the 20th anniversary of the official inauguration the SuperSTEM laboratory.
The SuperSTEM project began in 1997 when Prof. Mick Brown presented a now seminal paper presented at the 1997 Electron Microscopy and Analysis Group (EMAG) conference in Cambridge. Prof. Brown urged the UK scientific community to pool resources in a national microscopy centre that would offer access to an emerging new technological development called aberration correction - unveiled at the same conference by a team led by long-time collaborators Ondrej Krivanek and Niklas Dellby, which promised to “put a synchrotron in a microscope”. To realise this vision he teamed up with Peter Goodhew and Chris Kiely from the University of Liverpool, Rik Brydson at the University of Leeds, Alan Craven at the University of Glasgow and Andrew Bleloch from Cambridge to bid for funding for a "UK SuperSTEM National Facility", which was later to become the EPSRC National Research Facility (NRF) for Advanced Electron Microscopy.
Some twenty years after SuperSTEM's inauguration, aberration correctors are ubiquitous, with scientists the world over taking advantage of the improved sensitivity and resolution that they have brought about. Throughout this exceptional period of innovation in EM, SuperSTEM has continued to honour the spirit of its inception by offering early access to successive generations of new technologies with a view to demonstrate their benefit and importance to the scientific community: aberration correction , atomically resolved chemical mapping, low beam energy microscopy at atomic resolution (the first images of graphene at 60kV acceleration voltage), single-atom spectroscopy in the meV regime (bonding analysis, plasmonics and phononics of single atoms), to name but a few "world firsts".
SuperSTEM serves the research community by offering access to world-leading scanning transmission electron microscopy (STEM) instrumentation and expertise for the direct imaging and spectroscopy of atomic structures and the determination of chemical composition, bonding and vibrational properties, with a focus on single-atom precision and sensitivity. The facility's unique instrumentation enables the elucidation of structure-property relationships in materials and devices for the benefit of a highly multi-disciplinary scientific community, both academic and industrial, stemming from fields as diverse as catalysis, energy conversion and storage, biomaterials, organic and inorganic chemistry, mineralogy, planetary science, nuclear materials, condensed matter physics and quantum materials.
Since being awarded NRF status in 2011, the facility has proudly supported >400 distinct user groups from 21 countries, resulting in the publication of over 450 papers and underpinning a research portfolio of over £150M in EPSRC funding alone.
We cannot thank enough our collaborators and members of staff past and present for an amazing 20 years - as well as EPSRC for continued financial support: we look forward to even more exciting science in the coming two decades!
SuperSTEM on BBC4 documentary
Join us on Prof Jim Al-Khalili's brand new two episode documentary Secrets of Size: Atoms to Supergalaxies. The episode celebrates the wonderfull world of the nano, through the eyes of electron microscopes and features pioneering work on aberration correction, including that of our very own Prof. Ondrej Krivanek, laureate of the 2020 Kavli Prize for Nanoscience,
The monochromated SuperSTEM3 instrument has been retrofitted with a Nion IRIS high energy resolution EELS spectrometer, equipped with a Dectris ELA direct electron detector. The energy resolution of the instrument has improved below 5meV.
SuperSTEM2 has been upgraded with an electrical pole piece for in-situ heating/biasing and a new Bruker XFlash 6T-100 large collection angle EDS detector for efficient chemical analysis. The delivery and installation of a Quantum Detectors Merlin direct electron detector upgrade for EELS is scheduled for February 2022.
Theory of magnon spectroscopy in STEM
In a new paper just published in Physical Review B, in collaboration with researchers from the University of Uppsala led by Dr Jan Rusz, we present a theory and a simulation of diffuse scattering due to the excitation of magnons in scanning transmission electron microscopy. The calculations indicate that magnons can present atomic contrast when detected by electron energy-loss spectroscopy using atomic-size electron beams.
The results presented indicate that the intensity of the magnon diffuse scattering in bcc iron at 300 K is 4 orders of magnitude weaker than the intensity of thermal diffuse scattering arising from atomic vibrations, meaning that experimental detection of a magnon signal appears very demanding, although recent instrumental developments are likely to at least partially alleviate the challenges. Successful fingerprinting of magnons in an electron microscope would create a radical way of studying the fundamentals of magnetic ordering and spin wave excitations, e.g., in material systems used for spintronics and spin caloritronics, where spin currents are propagated by magnons
Full paper: K. Lyon, A. Bergman, P. Zeiger, et-al Theory of magnon diffuse scattering in scanning transmission electron microscopy Phys. Rev. B 104, 214418 (2021)
BBC4 at SuperSTEM
Today we had the pleasure to host Prof Jim Al-Khalili to talk about all things electron microscopy & look at single atoms for BBC4's BigAndSmall. To mark the occasion here is the worlds smallest portrait of Jim made by FIB!!
Portrait credit to Aleksander B. Mosberg FIB ninja extraordinaire.
We are delighted to congratulate our very own Dr Demie Kepaptsoglou on her promotion to Senior Research Fellow at the University of York!
Announcing the NION IRIS
We are excited to announce the installation of the Nion IRIS high resolution EELS spectrometer. The IRIS, installed on our SSTEM3 Nion HERMES monochromated microscope is equipped with a Dectris ELA electron-counting detector. The new spectrometer will drastically improve the energy resolution and signal detection for ultra-low-loss-EELS measurements.
VirtualFIB is a Blender application template, developed by SuperSTEM staff scientist Aleksander Mosberg.
The program is designed to simplify and automate different scenarios encountered when doing FIB technique development. For more details click here.
New member of staff
We are delighted to announce that Dr Khalil El Hajraoui, has just joined the team as a SuperSTEM staff scientist! Khalil is an ins-in situ electric measurement specialist joining us from the International Iberian Nanotechnology Laboratory .
Farewell to Fredrik Hage
We bid farewell to our member of staff Dr. Fredrik Hage who is off to start his new adventure as Assistant Professor at the Department of Physics, University of Oslo, Norway. We are extremely proud for him but a little sad to see him go! We wish him the best of luck and success with his new post!
New Horizons for research through adventurous projects
Our member of staff and University of York Research Fellow Dr. Demie Kepaptsoglou has been awarded one of the highly competitive EPSRC New Horizons projects for supporting high-risk, adventurous mathematical and physical science project. The project - one of the 126 out of more than 1300 funded - is entitled: 'Seeing magnons at spin-to-charge-conversion interfaces' and aims to develop magnon EELS spectroscopy in an electron microscope.
Job vacancy for SuperSTEM research associate (University of York)
A fixed term postdoctoral appointment is available initially for 18 months, with a possibility for extension up to 24 months, via the University of York. The post will be based at the SuperSTEM Laboratory, to work with the on-site facility team, on the EPSRC New Horizons 2020 Project “Seeing magnons at spin-to-charge conversion interfaces”. We are seeking an ambitious electron microscopist who will be responsible for research on this project, developing the methodology for vibrational and magnon electron energy loss spectroscopy in an electron microscope.
For more details for the post and application process:
Informal inquires can be addressed to Dr. Demie Kepaptsoglou
Exploring the functional chemistry of carbonaceous meteorites
Carbonaceous chondrites provide important samples of the very early solar nebula. These complex rocks recorded snapshots of events 4.57 Ga ago that can be disentangled by advanced analytical techniques on Earth. In a new study recently published in Scientific Reports, Dr Christian Vollmer from the University of Münster (Germany) , in collaboration with researchers from the Max Planck Institute for Chemistry (Mainz Germany), the Natural History Museum (London, UK) , the Diamond Light Source (Didcot, UK) and SuperSTEM, explore the functional chemistry of the Maribo carbonaceous chondrite, an observed fall from Denmark in 2009.
The study, combining STEM-EELS, Nano-SIMS and STXM looks into fine-grained organic matter within less altered matrix regions of the Maribo, demonstrates the relatively unaltered nature of this OM. The combined high-spatial resolution analyses of primitive matrix components therefore highlight the important character of Maribo as a key sample of the very early solar nebula.
Full Paper : Vollmer, C., Leitner, J., Kepaptsoglou, D. et al. A primordial 15N-depleted organic component detected within the carbonaceous chondrite Maribo. Sci Rep 10, 20251 (2020).
New Member of Staff
We are delighted to announce that Dr Aleksander Buseth Mosberg, has just joined the team as a SuperSTEM staff scientist! Aleskander is a FIB specialist joining us from NTNU: Norwegian University of Science and Technology
New Member of Staff
We are delighted to announce that Dr Paul Sharp , has just joined the team as a computational scientist! Paul will also be a part of the STFC Scientific Computing Department and will be working on structure discovery, electronic structure calculations and EELS simulations.
RMS Mid-Career Scientific Achievement Award 2020 goes to Quentin Ramasse
We are delighted to congratulate our very own Prof Quentin Ramasse on being one of the six recipients of the RMS Mid-Career Scientific Achievement Award 2020. The award celebrates and marks outstanding scientific achievements in any area of microscopy or flow cytometry for established, mid-career researchers. Pop the bottle!
Paper on Hyperbolic Metamaterial Nanostructures on the cover of Advanced Optical Materials
Optical metamaterials are composed of sub‐wavelength structures and exhibit unusual electromagnetic properties not observed in nature. One class of these materials, hyperbolic metamaterials (HMMs), is highly anisotropic media with opposite signs of permittivity tensor components in different directions. These materials can be engineered to have unusual properties, including broadband perfect absorption using particles or gratings, negative refraction, and resonant gain singularities. There is a wide range of potential uses enabled by these properties, such as sub‐diffraction resolved imaging, optical cloaking, single‐molecule biosensing, and applications in nonlinear optics and quantum optical circuits.
In a new study, recently published in Advanced Optical Materials, researchers from the Instituto Italiano di Tecnologia (IIT), in collaboration with SuperSTEM’s Quentin Ramasse, explore the spatial distribution of plasmon polaritons in multilayered HMM nanostructures. They show that HMM pillars are useful for their separation and adjustability of optical scattering and absorption, while HMM slot cavities can be used as waveguides with high field confinement. The nature of the modes is confirmed with corresponding simulations of EEL and optical spectra and near‐field intensities.
The work was selected for the front cover of the July 2020 issue
Full paper: T. Isoniemi, N. Maccaferri Q. M. Ramasse, G. Strangi, F. De Angelis, Adv. Optical Mater. 2020, 8, 200277
EMS Outstanding Paper Award for the year 2019
We are very pleased to announce that our Physical Review Letters, 122, 016103 (2019), on “Phonon Spectroscopy at Atomic Resolution”, by F. S. Hage, D. M. Kepaptsoglou, Q. M. Ramasse, and L. J. Allen, has received the 2019 European Microscopy Society Outstanding Paper Award, in Instrumentation and Technique Development.
Find the paper here: https://doi.org/10.1103/PhysRevLett.122.016103
Accurate EELS background subtraction – an adaptable method in MATLAB
Electron energy-loss spectroscopy (EELS) is a technique that can give useful information on elemental composition and bonding environments. However in practice, the complexity of the background contributions, which can arise from multiple sources, can hamper the interpretation of the spectra. As a result, background removal is both an essential and difficult part of EELS analysis, especially during quantification of elemental composition.
In a new article just published in Ultramicroscopy, Kayleigh Fung from the Nottigham NanoCarbon Group has developed in collaboration with SuperSTEM a series of scripts written in MATLAB v. R2019b that aims to provide statistical information on the model used to fit the background, allowing the user to determine the accuracy of background subtraction. The scripts were written for background subtraction of vibrational EELS in the ultralow-loss region near the zero-loss peak but can also be applied to other kinds of EEL spectra.
The scripts are freely available for download
Full paper: K.L.Y. Fung, M. W. Fay, S. M. Collins, et al , Accurate EELS background subtraction – an adaptable method in MATLAB, Ultramicroscopy (2020)
2020 Kavli Prize for Nanoscience recognises electron microscopy pioneers
It is an absolute pleasure and an honour to congratulate our very own Prof. Ondrej Krivanek for being awarded the 2020 Kavli Prize for Nanoscience, alongside fellow pioneers of aberration correction and electron microscopy Prof. Harald Rose and Prof. Max Haider, and Prof. Knut Urban.
Without Ondrej and of course without Nion co-founder Niklas Dellby (although not on the recipient list today, Niklas has been absolutely key in the revolution in electron microscopy we have all witnessed), there simply would not be a SuperSTEM Laboratory. It has been a true privilege to work with them for over two decades, from the early days of the Mark I STEM corrector at the Cavendish Laboratory in Cambridge to the dizzying heights of meV EELS these past few years.
From all of us at SuperSTEM, past and present, thank you and congratulations on this most deserved of awards!!
Join us on a plasmonic picnic in ACS Nano: studying the plasmonic response of singly-twinned Mg tents, chairs, tacos and kites!
To beat the confinement blues, nothing like a (plasmonic) picnic! In a recently published ACS Nano paper, SuperSTEM collaborators Jeremie Asselin, Emilie Ringe and their colleagues at the University of Cambridge study the plasmonic properties of singly-twinned Mg nanoparticles with shapes resembling tents (aptly named “canadiennes” in French), chairs, tacos or kites. Beyond the array of unusual shapes, these NPs, made from earth-abundant magnesium, provide interesting ways to control light at the nanoscale across the ultraviolet, visible, and near-infrared spectral ranges. The study combines numerical predictions and experimental observations including high energy resolution EELS to provide shape prediction, shape characterization, far-field scattering properties and near-field light localization of these exciting nano-object
Full paper: J. Asselin, C. Boukouvala, E.R. Hopper et al., Tents, chairs, tacos, kites and rods: shapes and plasmonic properties of singly twinned magnesium nanoparticles, ACS Nano (2020)
Home working - Updated "Resources" section
Due to the on-going Covid-19 pandemic, the majority of students and researchers are now working from home, many of whom do not have access to specialist software tools.
To help our users and community we are continuously updating our Resources page with links to useful software for data analysis and simulations.
We encourage all researchers that have suggestions about additional resources, tutorials, or have developed analysis code they would be willing to share with the community, to contact us so we can update the list.
8th SuperSTEM Summer School 2020 postponed by a year
We are very sorry to announce that the uncertainties surrounding the current Covid-19 epidemic have led us to take the very difficult decision to postpone the 8th SuperSTEM summer school until the summer of 2021. Even if some travel restrictions are lifted by July, we felt the disruptions we are all facing at the moment would make it impractical (and possibly unsafe) to organise or plan your travels to the event.
Although the exact date is not yet fixed, we are aiming to hold the 2021 summer school around the same time of the year as planned for this year, i.e. early July.
We will of course offer you the option to roll over your application to next year, hoping that your personal circumstances will still allow you to take part. We will contact you ahead of the official application phase for next year. Of course, do check our events page for updates on the summer school and let us know if you have any questions.
In the meantime, please all stay safe, and we look forward to seeing you in Daresbury in happier circumstances.
On behalf of the school organising committee.
Prof Quentin Ramasse
'Seeing' single atom vibrations with a STEM microscope
The modification of vibrational properties of materials by single atom point defects has been predicted for decades. In a paper just published in Science, SuperSTEM scientists Dr F. Hage, D. Kepaptsoglou and Prof. Q. Ramasse. in collaboration with Dr. G. Radtke and Dr. M. Lazzeri of Sorbonne Université (France), used electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM) and first principles calculations to record and understand the characteristic vibrational response of an individual silicon atom defect in single layer graphene.
The finely focused electron beam in our microscope allowed for probing this response atom-by-atom, revealing that the defect-induced characteristic vibrational signal is, by and large, localised on the Si atom itself. Our chosen approach should be applicable to atomically precise vibrational response measurements of defects and other inhomogeneities within a wide range of materials systems, in the electron microscope.
Full paper: F. S. Hage, G. Radtke, et al., Single-atom vibrational spectroscopy in the scanning transmission electron microscope, Science (2020)
Mapping functional groups with vibrational spectroscopy: resolution <15nm achieved
Vibrational spectroscopies directly record details of bonding in materials, but spatially resolved methods have been limited to surface techniques for mapping functional groups at the nanoscale. Electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope presents a route to functional group analysis from nanoscale volumes using transmitted subnanometer electron probes. In a new paper just published in Nano Letters, SuperSTEM associate Dr Sean Collins from the University of Cambridge in collaboration with staff members Dr. Demie Kepaptsoglou and Prof Quentin Ramasse, demonstrate that vibrational EELS can be used to map linkers in a metal–organic framework (MOF) crystal–glass composite material, with recorded spatial resolution <15 nm at interfaces in the composite. These results present a complete nanoscale analysis of the building blocks of the MOF composite and establish spatially resolved functional group analysis using electron beam spectroscopy for crystalline and amorphous organic and metal–organic solids.
Full paper: S. M. Collins, D.M. Kepaptsoglou, J. Hou, et al, Functional Group Mapping by Electron Beam Vibrational Spectroscopy from Nanoscale Volumes, Nano Letters (2020)
Engineering grain boundaries at the 2D limit: ultra-high density of GBs in MoS2 catalyses the hydrogen evolution reaction
The best way to start the new year is with a new publication! SuperSTEM users at NTU in Singapore and IC2N in Barcelona, along with a long list of collaborators across the world including SuperSTEM's Quentin Ramasse, have developed a unique synthesis technique to produce the highest recorded density of grain boundaries in 2-dimensional sheets of MoS2, providing exceptional catalyzing capabilities in particular for the hydrogen evolution reaction. The study, published in Nature Communications on the 2nd of January, provides a thorough STEM structural study of these remarkable catalysts, along with real life demonstrations in full scale devices of their potential for hydrogen production. Be sure to browse the 45 page (!) supplementary material section for all the details..
Full paper: Y. He, P. Tang, Z. Hu et al., Engineering grain boundaries at the 2D limit for the hydrogen evolution reaction, Nature Communications 11, 57 (2020).
Happy 17th Birthday to SuperSTEM!
How our baby has grown!
We are delighted to announce that Dr Matthieu Bugnet, CNRS Associate Research Professor, from the National Institute of Applied Sciences of Lyon (INSA Lyon), has just joined the team as a visiting SuperSTEM staff scientist!
New sample finishing equipment installed
A Fischione 1040 Nano Mill for FIB specimen finishing and a Fischione 1051 TEM Mill for ion beam thinning have been added to the sample preparation toolkit of the facility. Both instruments are equipped with liquid nitrogen cooling capabilities for thinning sensitive samples.
The instruments are now open to user access: please submit proposals as for regular beam time access.
Shedding light on the functional chemistry of organic meteorites
Organic matter was widespread in the early solar nebula and might have played an important role for the delivery of prebiotic molecules to the early Earth. In a new study published in Meteoritics and Planetary Science, researcher Dr. Christian Vollmer (University of Munster, Germany) in collaboration with SuperSTEM and researchers from the Max Plank Institute for Chemistry (Mainz ,Germany) investigated the textures, isotopic compositions, and functional chemistry of organic grains in the Renazzo carbonaceous chondrite by combined high spatial resolution techniques, including vibrational spectroscopy using SuperSTEM's monochromated Hermes microscope. These combined high‐spatial resolution techniques offer a deeper understanding of the evolution and processing events of organic matter in diverse extraterrestrial environments such as parent body aqueous alteration.
Full paper: C. Vollmer et al., " Isotopic compositions, nitrogen functional chemistry, and low‐loss electron spectroscopy of complex organic aggregates at the nanometer scale in the carbonaceous chondrite Renazzo" , Meteoritics&Planetary Science (2019)
A Novel Strategy for Enhancement of Thermoelectric Response in Oxides
Nanostructuring is an efficient route for enhancing the thermoelectric response of materials. In a paper recently published in ACS Applied Materials and Interfaces, researchers from Prof. Robert Freer's group at the University of Manchester in collaboration with SuperSTEM demonstrate a report a new synthesis and engineering strategy for nanostructuring oxide ceramics and demonstrate its effectiveness on an important n-type thermoelectric SrTiO3. Using combined synthesis and heat treatment strategies led to the formation of a complex nanostructure within the grains, significantly enhancing the performance of thermoelectric oxides; the approach could find much wider application in providing valuable guidance in the routes to synthesize future target materials.
Full paper: F. Azough, et al "Self-Nanostructuring in SrTiO3: A Novel Strategy for Enhancement of Thermoelectric Response in Oxides" ACS Appl. Mater. Interfaces 11 (2019) 32833-32843
Farewell to Patricia
We bid farewell to our staff scientist Patricia Abellan Baeza who is moving on to new adventures at the Institut des Matériaux Jean Rouxe in Nantes, France. Best of luck with the move and every success in your new post! We'll miss you!
SuperSTEM User Forum – National Research Facility Update at mmc2019
Monday 1 July 2019, 11.30 – 13.30, Manchester Central
This informal pre-congress session will consist of brief recent scientific highlights from the facility, alongside an update on facility upgrade plans and scheduled instrumentation improvements.
These include the imminent installation of an advanced new spectrometer which promises to improve the energy resolution of SuperSTEM3 for EELS to below 5meV, off a high solid angle EDXS detector for SuperSTEM2, and the procurement of an advanced focused ion beam and sample preparation equipment to assist our users and collaborators in getting the most from their facility beamtime.
Current and prospective users will be able to directly discuss projects and access procedures with facility staff.
This forum is free to attend and includes a sandwich lunch. To register your interest, please email Katie Reynolds; email@example.com.
Last available places: Second Catania School on Electron Energy Loss Spectroscopy: from conventional to counting EELS; 22-25 July 2019
This spectroscopy school, organised by the BeyondNano Laboratory in collaboration with SuperSTEM and supported by the Esteem3 network, provides an intensive 4-day programme that incorporates lectures, computer laboratories, and microscope practicals to provide participants with comprehensive, hands-on training on key EELS topics and technology. This course reviews the basic theory and practice of EELS imaging and analysis in the TEM.
Some prior experience with electron microscopy and analytical techniques is recommended. By the end of the course, participants can expect to know how best to optimize the performance of their EELS hardware as well as their EELS experimental setups in order to capture and extract the maximum amount of information from their TEM samples.
Course directors: Dr Giuseppe Nicotra (BeyondNano), Prof. Quentin Ramasse (SuperSTEM)
Confirmed speakers: Dr Stefan Loffler (TU Wien), Dr Paolo Longo (Gatan Inc, USA), Dr Katherine E. MacArthur (Ernst Ruska-Centre), Dr Eiji Okunishi (Jeol Ltd.), Dr Pavel Potapov (TU Dresden), Prof. Quentin Ramasse (SuperSTEM Laboratory), Dr Nahid Talebi (Max Plank Institute for Solid Sate Rsearch)
All details are available on the school website: http://www.beyondnano.it/EELS-2019
UV optical response of single boron and nitrogen atom dopants in graphene
Tailoring of graphene’s already excellent properties is highly desirable for optimising its implementation in various devices. The incorporation of single atom substitutional impurities is a means by which control over electronic structure and plasmonic response can be achieved. Of particular interest for electronic and optoelectronic applications, boron and nitrogen impurities induce a p and n doped character in graphene, while also modifying its plasmonic response.
In a paper, just published in Advanced Functional Materials, researchers from SuperSTEM, in collaboration with Dr. Myron D. Kapetanakis (University of Alabama at Birmingham, AL, USA) and Dr. Juan-Carlos Idrobo (ORNL, TN, USA), investigate the extreme-UV optical response of individual boron and nitrogen atom impurities in graphene, at the atomic scale. Using a combination of STEM-EELS and DFT modelling, they show that atomic-scale energy-dependent variations in spectroscopic image contrast result directly from dopant-induced modifications of the electronic density of states.
SuperSTEM scientist to serve on the Editorial Board of Micron
Patricia Abellan, SuperSTEM staff scientist, was recently invited to join the Editorial Board of the journal Micron, an Elsevier well-stablished publication within the electron microscopy community dealing with research where advanced microscopy plays a central role.
Editorial Board members represent key scientific and technical areas of expertise with strong impact on the Micron readership and our research and development community. As a board member, Abellan will have the opportunity to assist Journal Editors and the publisher with such efforts as the identification of new/evolving topics for topical issues and outstanding authors for invited reviews, as well as assist the Journal Editors in the evaluation and in their decision if needed within the manuscript review process.
Upcoming event: SuperSTEM Scientific Forum and Users’ Workshop – 16-17 May 2019
Please mark your calendars for an exciting upcoming event this spring: the SuperSTEM Scientific Forum and Users’ Workshop. We are planning an informal 1 ½ day scientific meeting with presentations and lectures from the SuperSTEM user community and beyond, including national and international invited speakers. The event will also provide an opportunity to tour the facility and to see the instrumentation upgrades scheduled to be commissioned this year. An open forum will also take place with facility status update and a discussion of future capabilities to be included on the facility roadmap so it can continue to offer unique instrumentation to the community.
The scientific programme is currently being drawn up for the 16-17 May. Please consult the SuperSTEM Events webpage for further details as they become available
First ever demonstration of phonon spectroscopy at atomic resolution - Editors' Suggestion in PRL
The vibration of atoms in solids, or lattice dynamics, is described in terms of quantised collective oscillations of the nuclei, called phonon modes - vibrational waves propagating through matter at very specific frequencies. The work described in this collaboration between SuperSTEM and Prof. Les Allen at the University of Melbourne demonstrates for the first time the ability to map, or image, at atomic resolution the intensity variations of phonon modes across a crystalline sample, using vibrational EELS in the STEM. Phonons are central to modern physics, underpinning our understanding of phenomena such as superconductivity, thermal transport or even structural phase transitions, which in turn govern the properties of every-day functional materials. It is believed that the structure and chemistry of materials, all the way down to the single atom level, can affect the behaviour of phonons. Being able to probe these phenomena at the atomic scale, orders of magnitude higher than previously possible, is thus a step change in the experimental toolbox available to physicists, chemists and materials scientists alike. The methodology developed in this work also provides unprecedented insights into image formation mechanisms in the electron microscope, demonstrating conclusively and directly that inelastic scattering associated with phonons excitations plays a central role in generating the contrast widely used for atomic resolution high angle annular dark field electron microscopy.
Full paper: F.S. Hage, D.M. Kepaptsoglou, Q.M. Ramasse and L.J. Allen, “Phonon Spectroscopy at Atomic Resolution”, Physical Review Letters, 122, 016103 (2019).
For more details: https://doi.org/10.1103/PhysRevLett.122.016103
Unveiling the optical properties and coordination chemistry of metal–organic framework glass blends
Amorphous-MOFs are the amorphous analogue of crystalline metal–organic frameworks (MOFs): network solids in which inorganic nodes (clusters or metal ions) are linked via organic ligands in an infinite array. The diversity of bond strengths and structures possible in the coordination environment of MOFs gives rise to important properties; amorphous MOFs that retain such critical coordination are very promising due to their distinct optical properties.
In a new paper, just published in the Journal of the American Chemical society, researchers from the University of Cambridge in collaboration with SuperSTEM provide insights into the optical properties of a blend of two zeolitic imidazolate framework (ZIF) MOFS. A combined STEM-EELS and DFT study, reveals that the electronic structure of the precursor phases is retained in the ZIF glass blends. The study indicates that the distinct properties observed in glass blends arise from interactions between domains in the glass, presenting opportunities for engineering MOF glasses for dielectric optical applications.
Full paper: S.M. Collins , D.M. Kepaptsoglou , K.T. Butler, L. Longley, T.D. Bennett, Q.M. Ramasse, and P.A. Midgley, "Subwavelength Spatially Resolved Coordination Chemistry of Metal–Organic Framework Glass Blends", Journal of the American Chemical Society (2019).
Read more in: https://dx.doi.org/10.1021/jacs.8b11548