scholarly journals Capturing fingerprints of conical intersection: Complementary information of non-adiabatic dynamics from linear x-ray probes

2021 ◽  
Vol 8 (3) ◽  
pp. 034101
Author(s):  
Deependra Jadoun ◽  
Mahesh Gudem ◽  
Markus Kowalewski
Keyword(s):  
Conical Intersection ◽  
Complementary Information ◽  
X Ray ◽  
Adiabatic Dynamics

Synthesis and Characterization of a Fluorescent Dianthraceno­indacene

Synlett ◽  
2018 ◽  
Vol 29 (19) ◽  
pp. 2562-2566 ◽  
Author(s):  
Michael Haley ◽  
Conerd Frederickson ◽  
Joshua Barker ◽  
Justin Dressler ◽  
Zheng Zhou ◽  
...  
Keyword(s):  
Neutral Molecule ◽  
Conical Intersection ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Irreversible Reduction ◽  
Inside Out

A freely soluble dianthracenoindacene derivative has been synthesized using an ‘inside-out’ Friedel–Crafts alkylation method and is the first fluorescent diacenoindacene reported. Linear fusion of the anthracenes is confirmed by X-ray diffraction studies on the neutral molecule as well as its dianion. Based on predictions from our previous studies, this is also the least antiaromatic diacenoindacene derivative yet to be prepared, which is reflected in its highly negative and irreversible reduction. With its paratropicity essentially eliminated, we posit that the molecule is no longer deactivated by a conical intersection, typical of antiaromatic molecules, and therefore fluorescence is restored. This follows the trend shown in the related dianthracenopentalenes, with the reappearance of fluorescence when the outer acene groups are extended to linearly-fused anthracene moieties.

scholarly journals Stellar activity and coronal heating: an overview of recent results

2015 ◽  
Vol 373 (2042) ◽  
pp. 20140259 ◽  
Author(s):  
Paola Testa ◽  
Steven H. Saar ◽  
Jeremy J. Drake
Keyword(s):  
Magnetic Activity ◽  
Coronal Heating ◽  
Complementary Information ◽  
Stellar Activity ◽  
X Ray ◽  
Solar Observations ◽  
Term Evolution ◽  
Wide Range ◽  
Stellar Magnetic Fields

Observations of the coronae of the Sun and of solar-like stars provide complementary information to advance our understanding of stellar magnetic activity, and of the processes leading to the heating of their outer atmospheres. While solar observations allow us to study the corona at high spatial and temporal resolution, the study of stellar coronae allows us to probe stellar activity over a wide range of ages and stellar parameters. Stellar studies therefore provide us with additional tools for understanding coronal heating processes, as well as the long-term evolution of solar X-ray activity. We discuss how recent studies of stellar magnetic fields and coronae contribute to our understanding of the phenomenon of activity and coronal heating in late-type stars.

Nitridation by NO Or N2O of Si-SiO2 Interfaces

1999 ◽  
Vol 567 ◽  
Author(s):  
A. P. Caricato ◽  
F. Cazzaniga ◽  
G. F. Cerofolini ◽  
B. Crivelli ◽  
M. L. Polignano ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Nature ◽  
Surface Recombination ◽  
Surface Recombination Velocity ◽  
Oxide Surface ◽  
Complementary Information ◽  
X Ray ◽  
Recombination Velocity ◽  
Foreign Species

ABSTRACTX-ray photoelectron spectroscopy (XPS) and photocurrent measurements for the determination of surface recombination velocity provide complementary information on the structure of the Si-SiO2 interface, being sensitive to the chemical nature of foreign species at the interface the former, and to intrinsic defects the latter. The comparison of the XPS N(1s) peaks determined for the Si-Si0 2 interfaces nitrided in NO or N2O ambients is useful to identify the species responsible for the broadening of the peak. In fact, nitridation by NO is mainly responsible for the formation of Si3N moieties at the silicon surface in which silicon atoms are partially oxidized; while nitridation by N2O proceeds with the oxidation of Si – Si backbonds to Si – N bonds, thus resulting in the formation of N(Si(O-)3)3 groups embedded in the oxide. Surface recombination velocity by photocurrent measurements gives evidence that nitridation in N2O is associated with an appreciable co-oxidation, while nitridation in NO is mainly associated with the passivation of interface states. Furthermore N2O and NO nitridation are responsible for different morphologies of the nitrided layers.

X-Ray Spectrometry Study on Historical Decorative Glasses in Thailand: Lanna-Style Glass

2012 ◽  
Vol 620 ◽  
pp. 330-334
Author(s):  
Pisutti Dararutana ◽  
Krit Won-In ◽  
Sawet Intarasiri ◽  
Teerasak Kamwanna ◽  
Somchai Tancharakorn ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Fluorescence Spectroscopy ◽  
Emission Spectroscopy ◽  
Complex Nature ◽  
Complementary Information ◽  
X Ray ◽  
Analytical Instruments ◽  
Spatially Resolved ◽  
Historical Objects ◽  
Glassy Materials

t was known that historical objects were highly heterogeneous. Due to the complex nature of materials and objects, extremely sensitive, spatially resolved, multi-elemental and versatile analytical instruments were needed. The techniques employed should be as a noninvasive as possible and able to give complementary information from macroscopic to nanometer scales. In this work, X-ray based spectroscopy including energy dispersive X-ray fluorescence spectroscopy (EDS), Proton-induced X-ray emission spectroscopy (PIXE), and micro-beam X-ray fluorescence spectroscopy (µ-XRF) were used to analyze chemical composition of the Lanna-style glass. Microstructure was also studied. It can be concluded that these techniques in combination are powerful for the investigation of heterogeneous glassy materials.

scholarly journals Resolving Competing Conical Intersection Pathways: Time-Resolved X-ray Absorption Spectroscopy of trans-1,3-Butadiene

2021 ◽  
Author(s):  
Issaka Seidu ◽  
Simon Neville ◽  
Ryan J MacDonell ◽  
Michael S. Schuurman
Keyword(s):  
Absorption Spectroscopy ◽  
Conical Intersection ◽  
Theoretical Studies ◽  
Nuclear Dynamics ◽  
Time Resolved ◽  
X Ray ◽  
Excited Molecules ◽  
X Ray Absorption

Time-resolved X-ray absorption spectroscopy is emerging as a uniquely powerful tool to probe coupled electronic-nuclear dynamics in photo-excited molecules. Theoretical studies to date have established that time-resolved X-ray absorption spectroscopy...

scholarly journals Unveiling the spatial distribution of molecular coherences at conical intersections by covariance X-ray diffraction signals

2021 ◽  
Vol 118 (22) ◽  
pp. e2105046118
Author(s):  
Stefano M. Cavaletto ◽  
Daniel Keefer ◽  
Jérémy R. Rouxel ◽  
Flavia Aleotti ◽  
Francesco Segatta ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Three Dimensional ◽  
Laser Pulses ◽  
Conical Intersection ◽  
Conical Intersections ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Diffraction Imaging ◽  
The Rich

The outcomes and timescales of molecular nonadiabatic dynamics are decisively impacted by the quantum coherences generated at localized molecular regions. In time-resolved X-ray diffraction imaging, these coherences create distinct signatures via inelastic photon scattering, but they are buried under much stronger background elastic features. Here, we exploit the rich dynamical information encoded in the inelastic patterns, which we reveal by frequency-dispersed covariance ultrafast powder X-ray diffraction of stochastic X-ray free-electron laser pulses. This is demonstrated for the photoisomerization of azobenzene involving the passage through a conical intersection, where the nuclear wave packet branches and explores different quantum pathways. Snapshots of the coherence dynamics are obtained at high frequency shifts, not accessible with conventional diffraction measurements. These provide access to the timing and to the confined spatial distribution of the valence electrons directly involved in the conical intersection passage. This study can be extended to full three-dimensional imaging of conical intersections with ultrafast X-ray and electron diffraction.

scholarly journals Monitoring nonadiabatic dynamics in molecules by ultrafast X-Ray diffraction

2019 ◽  
Vol 205 ◽  
pp. 09032
Author(s):  
Markus Kowalewski ◽  
Kochise Bennett ◽  
Shaul Mukamel
Keyword(s):  
Inelastic Scattering ◽  
Nonadiabatic Dynamics ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Avoided Crossing ◽  
Adiabatic Dynamics ◽  
Nuclear Configuration

We theoretically examine time-resolved diffraction from molecules which undergo non-adiabatic dynamics and identify contributions from inelastic scattering that indicate the presence of an avoided crossing and the corresponding nuclear configuration.

Structure determination of quasicrystals and neutron scattering

2000 ◽  
Vol 215 (10) ◽  
Author(s):  
M. de Boissieu
Keyword(s):  
Neutron Scattering ◽  
Cross Section ◽  
Structure Determination ◽  
Energy Analysis ◽  
Neutron Cross Section ◽  
Contrast Variation ◽  
Complementary Information ◽  
X Ray ◽  
Atomic Contribution

We review the use of neutron scattering in the structure determination of quasicrystals. The contrast between X-ray and neutron cross-section gives a useful complementary information. When feasible, contrast variation techniques allow to disentangle the different atomic contribution. Diffuse scattering studies are also simplified, thanks to the possibility of an energy analysis. We discuss results obtained in the case of the i-AlPdMn phase.

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