Synchrotron radiation techniques in materials and environmental science

Catlow, C. Richard A.

doi:10.1098/rsta.2013.0162

Cited by 7 publications

(6 citation statements)

References 24 publications

(36 reference statements)

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“…Figure C and D shows how the two terminal CH 2 S and CH 2 Fc units of S-(CH 2 ) 11 -Fc point in the same direction with respect to the backbone of the molecule when n = even ( n even ), but not for n = odd ( n odd ). Using a combination of electrochemistry, synchrotron based spectroscopy, electrical measurements, and computer simulations, we demonstrated that S-(CH 2 ) 11 -Fc SAMs on Ag with n odd stand more erect than molecules with n even . Because the metal–S–C bond angle is fixed, the odd–even effect in S-(CH 2 ) 11 -Fc SAM is caused by the odd–even effect in vdW interactions between Fc units of neighboring molecules in the SAM (Figure ).…”

Section: Odd–even Effects: What a Difference One Methylene Makesmentioning

confidence: 97%

Even the Odd Numbers Help: Failure Modes of SAM-Based Tunnel Junctions Probed via Odd-Even Effects Revealed in Synchrotrons and Supercomputers

Thompson

Nijhuis

2016

Acc. Chem. Res.

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This Account describes a body of research in atomic level design, synthesis, physicochemical characterization, and macroscopic electrical testing of molecular devices made from ferrocene-functionalized alkanethiol molecules, which are molecular diodes, with the aim to identify, and resolve, the failure modes that cause leakage currents. The mismatch in size between the ferrocene headgroup and alkane rod makes waxlike highly dynamic self-assembled monolayers (SAMs) on coinage metals that show remarkable atomic-scale sensitivity in their electrical properties. Our results make clear that molecular tunnel junction devices provide an excellent testbed to probe the electronic and supramolecular structures of SAMs on inorganic substrates. Contacting these SAMs to a eutectic "EGaIn" alloy top-electrode, we designed highly stable long-lived molecular switches of the form electrode-SAM-electrode with robust rectification ratios of up to 3 orders of magnitude. The graphic that accompanies this conspectus displays a computed SAM packing structure, illustrating the lollipop shape of the molecules that gives dynamic SAM supramolecular structures and also the molecule-electrode van der Waals (vdW) contacts that must be controlled to form good SAM-based devices. In this Account, we first trace the evolution of SAM-based electronic devices and rationalize their operation using energy level diagrams. We describe the measurement of device properties using near edge X-ray absorption fine structure spectroscopy, cyclic voltammetry, and X-ray photoelectron spectroscopy complemented by molecular dynamics and electronic structure calculations together with large numbers of electrical measurements. We discuss how data obtained from these combined experimental/simulation codesign studies demonstrate control over the supramolecular and electronic structure of the devices, tuning odd-even effects to optimize inherent packing tendencies of the molecules in order to minimize leakage currents in the junctions. It is now possible, but still very costly to create atomically smooth electrodes and we discuss progress toward masking electrode imperfections using cooperative molecule-electrode contacts that are only accessible by dynamic SAM structures. Finally, the unique ability of SAM devices to achieve simultaneously high and atom-sensitive electrical switching is summarized and discussed. While putting these structures to work as real world electronic devices remains very challenging, we speculate on the scientific and technological advances that are required to further improve electronic and supramolecular structure, toward the creation of high yields of long-lived molecular devices with (very) large, reproducible rectification ratios.

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Section: Odd–even Effects: What a Difference One Methylene Makesmentioning

confidence: 97%

Even the Odd Numbers Help: Failure Modes of SAM-Based Tunnel Junctions Probed via Odd-Even Effects Revealed in Synchrotrons and Supercomputers

Thompson

Nijhuis

2016

Acc. Chem. Res.

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“…The SR technique has some advantageous characteristics such as wide spectrum range, high intensity, high polarization, small source and therefore greater intensity; it has been beneficial for the applications in the fields of materials characterization and analysis, chemistry, micromechanics, biology, physics, geology, archaeology and medicine [244,245]. SR-based X-ray diffraction (XRD) and small-angle X-ray scattering (SAXS) characterization methods provide performance-related information about morphology and structural differences [246].…”

Section: 2synchrotron Radiation (Sr)mentioning

confidence: 99%

Porosimetric membrane characterization techniques: A review

Tanis-Kanbur

Peinador

Calvo

et al. 2021

Journal of Membrane Science

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“…PM can carry both inorganic and organic contaminants through atmospheric processes and tends to be highest in urban locations (Chan et al, 2000). Ambient particulates are also characterized as carriers of toxic heavy metals into the human body through inhalation into the lungs (Avino et al, 2008;Gharaibeh et al, 2010;Oucher et al, 2015;Hsu et al, 2016;Ahmad et al, 2019;Khan et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

“…Synchrotron-based techniques have played, over the last three decades, a significant role in materials and environmental sciences (Zaki & Imam, 2017). Their ability to gain accurate data at the atomic and molecular level on both local and long-range structures, jointly with the increasing ability to carry out time-resolved studies, has affected our understanding of various key types of functional materials, while their strength as analytical tools has a major influence on issues of environmental studies (Catlow, 2015).…”

Section: Introductionmentioning

confidence: 99%

Heavy metals concentrations and speciation of Pb and Ni in airborne particulate matter over two residential sites in Greater Cairo – reflection from synchrotron radiation

et al. 2022

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Synchrotron radiation-based techniques [X-ray absorption near-edge structure (XANES) and X-ray fluorescence (XRF)] combined with inductively coupled plasma-mass spectrometry (ICP-MS) were used for the assessment of heavy metals concentrations as well as lead (Pb) and nickel (Ni) speciation in airborne particulate matter (PM10) over two residential sites in Greater Cairo. Nineteen 24 h high-volume samples collected at Giza (G) Square and Helwan (H) University (Egypt) were selected for this study. Mean concentrations of heavy metals in PM10 at both sites were found to have the same descending order of Pb > Cu > Ni > Cd > Co > As, of which concentrations of Pb, Cu, Ni and Cd in H samples were higher than those in G samples. For Pb, synchrotron-based XRF results were in good agreement with concentrations obtained by ICP-MS. The XANES spectra of PM10 at the Pb L 2-edge and Ni K-edge were compared with those of Pb and Ni in model standard compounds to provide information on the potential oxidation states as well as the chemical forms of those elements. The data show that Pb has similar chemical environments in both series G and H with the predominance of Pb2+ oxidation state. Nickel was found as Ni(OH)2, NiO and Ni metal in the analyzed samples. However, the content of Ni in the background filter shows a very strong interference with that of the collected PM10. Carcinogenic and non-carcinogenic risks resulting from the inhalation of the studied heavy metals were assessed for children and adult residents and were found below the safe limits, at both sites.

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Synchrotron radiation techniques in materials and environmental science

Abstract: One contribution of 15 to a theme issue 'Research achieved with Diamond and future perspectives' .

Cited by 7 publications

References 24 publications

Even the Odd Numbers Help: Failure Modes of SAM-Based Tunnel Junctions Probed via Odd-Even Effects Revealed in Synchrotrons and Supercomputers

Even the Odd Numbers Help: Failure Modes of SAM-Based Tunnel Junctions Probed via Odd-Even Effects Revealed in Synchrotrons and Supercomputers

Porosimetric membrane characterization techniques: A review

Heavy metals concentrations and speciation of Pb and Ni in airborne particulate matter over two residential sites in Greater Cairo – reflection from synchrotron radiation

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