scholarly journals Ultrafast electron injection into photo-excited organic molecules

2016 ◽  
Vol 18 (32) ◽  
pp. 22140-22145 ◽  
Author(s):  
Dean Cvetko ◽  
Guido Fratesi ◽  
Gregor Kladnik ◽  
Albano Cossaro ◽  
Gian Paolo Brivio ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Organic Molecules ◽  
State Of The Art ◽  
Energy Levels ◽  
Electron Injection ◽  
Metal Substrate ◽  
Molecular Adsorption ◽  
X Ray ◽  
Excited Molecules ◽  
Adsorption Geometry

State-of-the-art X-ray spectroscopy allows femtosecond gating of energy levels of photo-excited molecules on a metal substrate enabling ultrafast and bi-directional charge transfer across the interface with controllable dependence on the molecular adsorption geometry.

Tuning ultrafast electron injection dynamics at organic-graphene/metal interfaces

Nanoscale ◽  
2018 ◽  
Vol 10 (17) ◽  
pp. 8014-8022 ◽  
Author(s):  
Abhilash Ravikumar ◽  
Gregor Kladnik ◽  
Moritz Müller ◽  
Albano Cossaro ◽  
Gregor Bavdek ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Ab Initio ◽  
Electron Injection ◽  
Bilayer Graphene ◽  
X Ray ◽  
Metal Interfaces ◽  
Charge Transfer Dynamics ◽  
Ultrafast Charge Transfer

We assess ultrafast charge transfer dynamics between molecules and epitaxial or bilayer graphene/Ni(111) interfaces by ab initio theory and X-ray spectroscopy.

Femtosecond charge and molecular dynamics of I-containing organic molecules induced by intense X-ray free-electron laser pulses

2016 ◽  
Vol 194 ◽  
pp. 537-562 ◽  
Author(s):  
K. Nagaya ◽  
K. Motomura ◽  
E. Kukk ◽  
Y. Takahashi ◽  
K. Yamazaki ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Charge Transfer ◽  
Organic Molecules ◽  
Coulomb Explosion ◽  
Nuclear Motion ◽  
Charge Redistribution ◽  
Nuclear Dynamics ◽  
X Ray ◽  
Atomic Ions ◽  
Momentum Correlation

We studied the electronic and nuclear dynamics of I-containing organic molecules induced by intense hard X-ray pulses at the XFEL facility SACLA in Japan. The interaction with the intense XFEL pulse causes absorption of multiple X-ray photons by the iodine atom, which results in the creation of many electronic vacancies (positive charges) via the sequential electronic relaxation in the iodine, followed by intramolecular charge redistribution. In a previous study we investigated the subsequent fragmentation by Coulomb explosion of the simplest I-substituted hydrocarbon, iodomethane (CH3I). We carried out three-dimensional momentum correlation measurements of the atomic ions created via Coulomb explosion of the molecule and found that a classical Coulomb explosion model including charge evolution (CCE-CE model), which accounts for the concerted dynamics of nuclear motion and charge creation/charge redistribution, reproduces well the observed momentum correlation maps of fragment ions emitted after XFEL irradiation. Then we extended the study to 5-iodouracil (C4H3IN2O2, 5-IU), which is a more complex molecule of biological relevance, and confirmed that, in both CH3I and 5-IU, the charge build-up takes about 10 fs, while the charge is redistributed among atoms within only a few fs. We also adopted a self-consistent charge density-functional based tight-binding (SCC-DFTB) method to treat the fragmentations of highly charged 5-IU ions created by XFEL pulses. Our SCC-DFTB modeling reproduces well the experimental and CCE-CE results. We have also investigated the influence of the nuclear dynamics on the charge redistribution (charge transfer) using nonadiabatic quantum-mechanical molecular dynamics (NAQMD) simulation. The time scale of the charge transfer from the iodine atomic site to the uracil ring induced by nuclear motion turned out to be only ∼5 fs, indicating that, besides the molecular Auger decay in which molecular orbitals delocalized over the iodine site and the uracil ring are involved, the nuclear dynamics also play a role for ultrafast charge redistribution. The present study illustrates that the CCE-CE model as well as the SCC-DFTB method can be used for reconstructing the positions of atoms in motion, in combination with the momentum correlation measurement of the atomic ions created via XFEL-induced Coulomb explosion of molecules.

STATUS AND PLANS OF EXPERIMENT E17 AT J-PARC

2011 ◽  
Vol 26 (03n04) ◽  
pp. 604-606
Author(s):  
B. K. WUENSCHEK ◽  
H. BHANG ◽  
M. CARGNELLI ◽  
S. CHOI ◽  
C. CURCEANU ◽  
...  
Keyword(s):  
Strong Interaction ◽  
State Of The Art ◽  
Energy Levels ◽  
Level Shift ◽  
Semiconductor Detectors ◽  
X Ray ◽  
Kaonic Atoms ◽  
In Situ Calibration

X-ray spectroscopy is an advantageous tool for investigation of the shift and width of the energy levels in kaonic atoms, evoked due to strong interaction between nucleus and kaon. In order to study the 2p level shift in kaonic 3 He , the X-ray transition 3 p →2 d in liquid kaonic 3 He will be measured with a precision of <2 eV in the E17 experiment at J-PARC. To reach this desired precision, a well designed setup, in-situ calibration and state-of-the-art semiconductor detectors will be used. The idea and the preparation status of the whole setup will be reported in this article.

scholarly journals The structure of liquid alkali nitrates and nitrites

2017 ◽  
Vol 19 (32) ◽  
pp. 21625-21638 ◽  
Author(s):  
Martin C. Wilding ◽  
Mark Wilson ◽  
Mauro C. C. Ribeiro ◽  
Chris J. Benmore ◽  
J. K. R. Weber ◽  
...  
Keyword(s):  
Charge Transfer ◽  
State Of The Art ◽  
Simulation Models ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Of Liquid

State of the art high energy X-ray diffraction experiments and simulation models (employing a description of charge transfer) are applied to pure molten alkali nitrates and nitrites and uncover significant emerging structure.

High Resolution Replication of Organoclay Surfaces

1982 ◽  
Vol 40 ◽  
pp. 576-577
Author(s):  
W. W. Barker ◽  
W. E. Rigsby ◽  
V. J. Hurst ◽  
W. J. Humphreys
Keyword(s):  
Clay Mineral ◽  
Organic Molecule ◽  
Organic Molecules ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
X Ray ◽  
Naturally Occurring ◽  
Silicate Layers ◽  
Mineral Identification

Experimental clay mineral-organic molecule complexes long have been known and some of them have been extensively studied by X-ray diffraction methods. The organic molecules are adsorbed onto the surfaces of the clay minerals, or intercalated between the silicate layers. Natural organo-clays also are widely recognized but generally have not been well characterized. Widely used techniques for clay mineral identification involve treatment of the sample with H2 O2 or other oxidant to destroy any associated organics. This generally simplifies and intensifies the XRD pattern of the clay residue, but helps little with the characterization of the original organoclay. Adequate techniques for the direct observation of synthetic and naturally occurring organoclays are yet to be developed.

Revisiting the High-Pressure Properties of the Metal-Organic Frameworks ZIF-8 and ZIF-67

2020 ◽  
Author(s):  
Pia Vervoorts ◽  
Stefan Burger ◽  
Karina Hemmer ◽  
Gregor Kieslich
Keyword(s):  
High Pressure ◽  
State Of The Art ◽  
Energy Landscape ◽  
Structural Flexibility ◽  
Zeolitic Imidazolate Frameworks ◽  
Stimuli Responsive ◽  
X Ray Diffraction ◽  
X Ray ◽  
Open Questions ◽  
Metal Organic

The zeolitic imidazolate frameworks ZIF-8 and ZIF-67 harbour a series of fascinating stimuli responsive properties. Looking at their responsitivity to hydrostatic pressure as stimulus, open questions exist regarding the isotropic compression with non-penetrating pressure transmitting media. By applying a state-of-the-art high-pressure powder X-ray diffraction setup, we revisit the high-pressure behaviour of ZIF-8 and ZIF-67 up to <i>p</i> = 0.4 GPa in small pressure increments. We observe a drastic, reversible change of high-pressure powder X-ray diffraction data at <i>p</i> = 0.3 GPa, discovering large volume structural flexibility in ZIF-8 and ZIF-67. Our results imply a shallow underlying energy landscape in ZIF-8 and ZIF-67, an observation that might point at rich polymorphism of ZIF-8 and ZIF-67, similar to ZIF-4(Zn).<br>

Revisiting the High-Pressure Properties of the Metal-Organic Frameworks ZIF-8 and ZIF-67

2020 ◽  
Author(s):  
Pia Vervoorts ◽  
Stefan Burger ◽  
Karina Hemmer ◽  
Gregor Kieslich
Keyword(s):  
High Pressure ◽  
State Of The Art ◽  
Energy Landscape ◽  
Structural Flexibility ◽  
Zeolitic Imidazolate Frameworks ◽  
Stimuli Responsive ◽  
X Ray Diffraction ◽  
X Ray ◽  
Open Questions ◽  
Metal Organic

The zeolitic imidazolate frameworks ZIF-8 and ZIF-67 harbour a series of fascinating stimuli responsive properties. Looking at their responsitivity to hydrostatic pressure as stimulus, open questions exist regarding the isotropic compression with non-penetrating pressure transmitting media. By applying a state-of-the-art high-pressure powder X-ray diffraction setup, we revisit the high-pressure behaviour of ZIF-8 and ZIF-67 up to <i>p</i> = 0.4 GPa in small pressure increments. We observe a drastic, reversible change of high-pressure powder X-ray diffraction data at <i>p</i> = 0.3 GPa, discovering large volume structural flexibility in ZIF-8 and ZIF-67. Our results imply a shallow underlying energy landscape in ZIF-8 and ZIF-67, an observation that might point at rich polymorphism of ZIF-8 and ZIF-67, similar to ZIF-4(Zn).<br>

Infra-Red Reflectance Microscopy (IRRM) for Daisy Chain Flip Chip Device Failure Analysis

2004 ◽  
Author(s):  
Carlo Grilletto ◽  
Steve Hsiung ◽  
Andrew Komrowski ◽  
John Soopikian ◽  
Daniel J.D. Sullivan ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Flip Chip ◽  
State Of The Art ◽  
Failure Mechanisms ◽  
Simple Metal ◽  
X Ray ◽  
Infra Red ◽  
Cause Of Failure ◽  
Reflectance Microscopy ◽  
Ir Emission

Abstract This paper describes a method to "non-destructively" inspect the bump side of an assembled flip-chip test die. The method is used in conjunction with a simple metal-connecting "modified daisy chain" die and makes use of the fact that polished silicon is transparent to infra-red (IR) light. The paper describes the technique, scope of detection and examples of failure mechanisms successfully identified. It includes an example of a shorting anomaly that was not detectable with the state of the art X-ray equipment, but was detected by an IR emission microscope. The anomalies, in many cases, have shown to be the cause of failure. Once this has been accomplished, then a reasonable deprocessing plan can be instituted to proceed with the failure analysis.

scholarly journals COVID-19 infection map generation and detection from chest X-ray images

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Aysen Degerli ◽  
Mete Ahishali ◽  
Mehmet Yamac ◽  
Serkan Kiranyaz ◽  
Muhammad E. H. Chowdhury ◽  
...  
Keyword(s):  
State Of The Art ◽  
Ground Truth ◽  
Clinical Use ◽  
X Ray ◽  
Learning Techniques ◽  
Map Generation ◽  
Severity Grading ◽  
Chest X Ray ◽  
Novel Method ◽  
Aided Diagnosis

AbstractComputer-aided diagnosis has become a necessity for accurate and immediate coronavirus disease 2019 (COVID-19) detection to aid treatment and prevent the spread of the virus. Numerous studies have proposed to use Deep Learning techniques for COVID-19 diagnosis. However, they have used very limited chest X-ray (CXR) image repositories for evaluation with a small number, a few hundreds, of COVID-19 samples. Moreover, these methods can neither localize nor grade the severity of COVID-19 infection. For this purpose, recent studies proposed to explore the activation maps of deep networks. However, they remain inaccurate for localizing the actual infestation making them unreliable for clinical use. This study proposes a novel method for the joint localization, severity grading, and detection of COVID-19 from CXR images by generating the so-called infection maps. To accomplish this, we have compiled the largest dataset with 119,316 CXR images including 2951 COVID-19 samples, where the annotation of the ground-truth segmentation masks is performed on CXRs by a novel collaborative human–machine approach. Furthermore, we publicly release the first CXR dataset with the ground-truth segmentation masks of the COVID-19 infected regions. A detailed set of experiments show that state-of-the-art segmentation networks can learn to localize COVID-19 infection with an F1-score of 83.20%, which is significantly superior to the activation maps created by the previous methods. Finally, the proposed approach achieved a COVID-19 detection performance with 94.96% sensitivity and 99.88% specificity.

scholarly journals The Degree of Oxidation of Graphene Oxide

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 560
Author(s):  
Alexandra Carvalho ◽  
Mariana C. F. Costa ◽  
Valeria S. Marangoni ◽  
Pei Rou Ng ◽  
Thi Le Hang Nguyen ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Ab Initio ◽  
State Of The Art ◽  
High Accuracy ◽  
Precise Determination ◽  
Photoemission Spectroscopy ◽  
Pristine Graphene ◽  
X Ray ◽  
Degree Of Oxidation

We show that the degree of oxidation of graphene oxide (GO) can be obtained by using a combination of state-of-the-art ab initio computational modeling and X-ray photoemission spectroscopy (XPS). We show that the shift of the XPS C1s peak relative to pristine graphene, ΔEC1s, can be described with high accuracy by ΔEC1s=A(cO−cl)2+E0, where c0 is the oxygen concentration, A=52.3 eV, cl=0.122, and E0=1.22 eV. Our results demonstrate a precise determination of the oxygen content of GO samples.

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