ULTRAFAST ATOMIC DISPLACEMENT IN OPTICAL AND SOFT X-RAY SPECTROSCOPIES

2001 ◽  
Vol 15 (28n30) ◽  
pp. 3690-3694
Author(s):  
YOSUKE KAYANUMA ◽  
SATOSHI TANAKA
Keyword(s):  
Excited State ◽  
Atomic Displacement ◽  
Pump Probe ◽  
X Ray ◽  
The Core ◽  
Spectral Hole ◽  
Exciton Excitation ◽  
Optical Region ◽  
Theoretical Standpoint

Recent advances in the spectroscopies of the second order processes both in the optical region and in the soft x-ray region are reviewed from a theoretical standpoint. A peculiar role of the breathing and oscillating spectral hole in the femtosecond pump-probe experiments is pointed out. The resonant x-ray emission spectrum in diamonds at the core-exciton excitation is analyzed by a simple model, and it is shown that a ultrafast off-center displacement occurs in the core-excited state.

scholarly journals The role of AGN activity in the building up of the BCG at z ∼ 1.6

2019 ◽  
Vol 15 (S356) ◽  
pp. 280-284
Author(s):  
Angela Bongiorno ◽  
Andrea Travascio
Keyword(s):  
Galaxy Cluster ◽  
Cluster Galaxy ◽  
X Ray ◽  
Groups Of Galaxies ◽  
Star Forming ◽  
The Core ◽  
The Galaxy ◽  
Multi Wavelength

AbstractXDCPJ0044.0-2033 is one of the most massive galaxy cluster at z ∼1.6, for which a wealth of multi-wavelength photometric and spectroscopic data have been collected during the last years. I have reported on the properties of the galaxy members in the very central region (∼ 70kpc × 70kpc) of the cluster, derived through deep HST photometry, SINFONI and KMOS IFU spectroscopy, together with Chandra X-ray, ALMA and JVLA radio data.In the core of the cluster, we have identified two groups of galaxies (Complex A and Complex B), seven of them confirmed to be cluster members, with signatures of ongoing merging. These galaxies show perturbed morphologies and, three of them show signs of AGN activity. In particular, two of them, located at the center of each complex, have been found to host luminous, obscured and highly accreting AGN (λ = 0.4−0.6) exhibiting broad Hα line. Moreover, a third optically obscured type-2 AGN, has been discovered through BPT diagram in Complex A. The AGN at the center of Complex B is detected in X-ray while the other two, and their companions, are spatially related to radio emission. The three AGN provide one of the closest AGN triple at z > 1 revealed so far with a minimum (maximum) projected distance of 10 kpc (40 kpc). The discovery of multiple AGN activity in a highly star-forming region associated to the crowded core of a galaxy cluster at z ∼ 1.6, suggests that these processes have a key role in shaping the nascent Brightest Cluster Galaxy, observed at the center of local clusters. According to our data, all galaxies in the core of XDCPJ0044.0-2033 could form a BCG of M* ∼ 1012Mȯ hosting a BH of 2 × 108−109Mȯ, in a time scale of the order of 2.5 Gyrs.

scholarly journals Analysis of a measurement scheme for ultrafast hole dynamics by few femtosecond resolution X-ray pump–probe Auger spectroscopy

2014 ◽  
Vol 171 ◽  
pp. 93-111 ◽  
Author(s):  
Bridgette Cooper ◽  
Přemysl Kolorenč ◽  
Leszek J. Frasinski ◽  
Vitali Averbukh ◽  
Jon P. Marangos
Keyword(s):  
Auger Spectroscopy ◽  
X Rays ◽  
Core Hole ◽  
Pump Probe ◽  
X Ray ◽  
Molecular Systems ◽  
The Core ◽  
Probe Delay ◽  
Valence Region ◽  
Hole Migration

Ultrafast hole dynamics created in molecular systems as a result of sudden ionisation is the focus of much attention in the field of attosecond science. Using the molecule glycine we show through ab initio simulations that the dynamics of a hole, arising from ionisation in the inner valence region, evolves with a timescale appropriate to be measured using X-ray pulses from the current generation of SASE free electron lasers. The examined pump–probe scheme uses X-rays with photon energy below the K edge of carbon (275–280 eV) that will ionise from the inner valence region. A second probe X-ray at the same energy can excite an electron from the core to fill the vacancy in the inner-valence region. The dynamics of the inner valence hole can be tracked by measuring the Auger electrons produced by the subsequent refilling of the core hole as a function of pump–probe delay. We consider the feasibility of the experiment and include numerical simulation to support this analysis. We discuss the potential for all X-ray pump-X-ray probe Auger spectroscopy measurements for tracking hole migration.

Role of Aluminide coating degradation on Inconel 713 LC used for Compressor Turbines (CT) of Short-haul Aircrafts

MRS Advances ◽  
2018 ◽  
Vol 3 (38) ◽  
pp. 2281-2296
Author(s):  
Joshua K. Ngoret ◽  
Venkata P. Kommula
Keyword(s):  
Aluminide Coating ◽  
Surface Coatings ◽  
Core Material ◽  
X Ray Diffraction ◽  
Early Failure ◽  
X Ray ◽  
The Core ◽  
Trailing Edges ◽  
Xrf Scanning

ABSTRACTThis paper investigates the role degradation of protective diffusion aluminide coating on Inconel 713LC used for CT blades of short-haul aircraft fleet played in having the blades prematurely retired from service at 6378 hours, as opposed to their pre-set service time of 10000 hours. The blade samples were subjected to various examinations; X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyse at the; tips, airfoil, as well as the base, transverse and longitudinal, sectioned and unsectioned. As affirmed by both the transverse and longitudinal sections examinations, it was established that thermal attack leading to deterioration of the coating was greater at the tip and airfoils of the blades (the hotter zones) and lesser towards the bases (colder zones). As a result, severe degradation of the core material at the tips and airfoils compared to the bases and more prevalent at the leading edges than trailing edges at the tips. The results further suggest that both active outward Ni diffusion and inward Al diffusion can coexist during exploitation of the blades in service. The study illustrates the role played by the aluminide coating in early failure of CT blades with the aim of bettering the surface coatings and enhancing coating technologies, managing CT blade material monitoring as well as to give insights on advancing CT blades maintenance practices.

scholarly journals Pump–probe XAS investigation of the triplet state of an Ir photosensitizer with chromenopyridinone ligands

2018 ◽  
Vol 17 (7) ◽  
pp. 896-902 ◽  
Author(s):  
Grigory Smolentsev ◽  
Kaj M. van Vliet ◽  
Nicolo Azzaroli ◽  
Jeroen A. van Bokhoven ◽  
Albert M. Brouwer ◽  
...  
Keyword(s):  
Excited State ◽  
Dft Calculations ◽  
Triplet State ◽  
Absorption Spectroscopy ◽  
Triplet Excited State ◽  
Pump Probe ◽  
X Ray ◽  
X Ray Absorption

The triplet excited state of a new Ir-based photosensitizer with two chromenopyridinone and one bipyridine-based ligands has been studied by pump–probe X-ray absorption spectroscopy (XANES) coupled with DFT calculations.

Simulations of Ground and Excited State X-ray Absorption Spectra for Molecules in Solution: The Role of the Solvent

2012 ◽  
Author(s):  
Thomas Penfold ◽  
Ivano Tavernelli ◽  
Rafael Abela ◽  
Ursula Rothlisberger ◽  
Majed Chergui
Keyword(s):  
Excited State ◽  
Absorption Spectra ◽  
X Ray ◽  
X Ray Absorption

Nuclear dynamics in the core-excited state of aqueous ammonia probed by resonant inelastic soft x-ray scattering

2011 ◽  
Vol 84 (10) ◽  
Author(s):  
L. Weinhardt ◽  
M. Weigand ◽  
O. Fuchs ◽  
M. Bär ◽  
M. Blum ◽  
...  
Keyword(s):  
Excited State ◽  
Aqueous Ammonia ◽  
Nuclear Dynamics ◽  
X Ray ◽  
The Core ◽  
X Ray Scattering ◽  
Ray Scattering

Structural role of tellurium in the minerals of the pearceite-polybasite group

2013 ◽  
Vol 77 (4) ◽  
pp. 419-428 ◽  
Author(s):  
L. Bindi ◽  
P. Voudouris ◽  
P. G. Spry
Keyword(s):  
Crystal Structure ◽  
Room Temperature ◽  
Atomic Displacement ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dimensional Diffusion ◽  
Diffusion Paths ◽  
Linear Coordination

AbstractThe crystal structure of a Te-rich polybasite has been refined by means of X-ray diffraction data collected at room temperature (space group Pm1; R = 0.0505 for 964 observed reflections and 94 parameters; refined formula Ag14.46Cu1.54Sb1.58As0.42S9.67Te1.33). The structure comprises stacking of [(Ag, Cu)6(Sb, As)2(S, Te)7]2–A and [Ag9Cu(S, Te)2(S, Te)2]2+B layer modules in which Sb forms isolated SbS3 pyramids, as occurs typically in sulfosalts, Cu links two S atoms in a linear coordination and Ag occupies sites with coordination ranging from quasi linear to almost tetrahedral. The silver d10 ions are found in the B layer module along two-dimensional diffusion paths and their electron densities evidenced by means of a combination of a Gram-Charlier development of the atomic displacement factors and a split model. The Te-for-S substitution occurs at the same structural sites that Se substitutes for S in selenopolybasite and the Te occupancy at one of these sites is 0.49, thus suggesting the possibility that 'telluropolybasite' could be found in nature.

scholarly journals Recoil-induced ultrafast molecular rotation probed by dynamical rotational Doppler effect

2019 ◽  
Vol 116 (11) ◽  
pp. 4877-4882 ◽  
Author(s):  
Denis Céolin ◽  
Ji-Cai Liu ◽  
Vinícius Vaz da Cruz ◽  
Hans Ågren ◽  
Loïc Journel ◽  
...  
Keyword(s):  
Delay Time ◽  
Doppler Effect ◽  
Auger Electron ◽  
Molecular Motion ◽  
General Point ◽  
Core Hole ◽  
Time Resolved ◽  
Pump Probe ◽  
X Ray ◽  
The Core

Observing and controlling molecular motion and in particular rotation are fundamental topics in physics and chemistry. To initiate ultrafast rotation, one needs a way to transfer a large angular momentum to the molecule. As a showcase, this was performed by hard X-ray C1s ionization of carbon monoxide accompanied by spinning up the molecule via the recoil “kick” of the emitted fast photoelectron. To visualize this molecular motion, we use the dynamical rotational Doppler effect and an X-ray “pump-probe” device offered by nature itself: the recoil-induced ultrafast rotation is probed by subsequent Auger electron emission. The time information in our experiment originates from the natural delay between the C1s photoionization initiating the rotation and the ejection of the Auger electron. From a more general point of view, time-resolved measurements can be performed in two ways: either to vary the “delay” time as in conventional time-resolved pump-probe spectroscopy and use the dynamics given by the system, or to keep constant delay time and manipulate the dynamics. Since in our experiment we cannot change the delay time given by the core-hole lifetime τ, we use the second option and control the rotational speed by changing the kinetic energy of the photoelectron. The recoil-induced rotational dynamics controlled in such a way is observed as a photon energy-dependent asymmetry of the Auger line shape, in full agreement with theory. This asymmetry is explained by a significant change of the molecular orientation during the core-hole lifetime, which is comparable with the rotational period.

scholarly journals Crystal structure of NirF: Insights into its role in heme d1 biosynthesis

2020 ◽  
Author(s):  
Thomas Klünemann ◽  
Manfred Nimtz ◽  
Lothar Jänsch ◽  
Gunhild Layer ◽  
Wulf Blankenfeldt
Keyword(s):  
Ligand Binding Site ◽  
Human Pathogen ◽  
X Ray ◽  
The Core ◽  
X Ray Scattering ◽  
Anoxic Environments ◽  
Opportunistic Human Pathogen ◽  
Heme D1 ◽  
Membrane Anchoring

AbstractCertain facultative anaerobes such as the opportunistic human pathogen Pseudomonas aeruginosa can respire on nitrate, a process generally known as denitrification. This enables denitrifying bacteria to survive in anoxic environments and contributes e.g. to the formation of biofilm, hence increasing difficulties in eradicating P. aeruginosa infections. A central step in denitrification is the reduction of nitrite to nitrous oxide by nitrite reductase NirS, an enzyme that requires the unique cofactor heme d1. While heme d1 biosynthesis is mostly understood, the role of the essential periplasmatic protein NirF in this pathway remains unclear. Here, we have determined crystal structures of NirF and its complex with dihydroheme d1, the last intermediate of heme d1 biosynthesis. We found that NirF forms a bottom-to-bottom β-propeller homodimer and confirmed this by multi-angle light and small-angle X-ray scattering. The N-termini are immediately neighbored and project away from the core structure, which hints at simultaneous membrane anchoring via both N-termini. Further, the complex with dihydroheme d1 allowed us to probe the importance of specific residues in the vicinity of the ligand binding site, revealing residues not required for binding or stability of NirF but essential for denitrification in experiments with complemented mutants of a ΔnirF strain of P. aeruginosa. Together, these data implicate that NirF possesses a yet unknown enzymatic activity and is not simply a binding protein of heme d1 derivatives.

scholarly journals Observation of femtosecond X-ray interactions with matter using an X-ray–X-ray pump–probe scheme

2016 ◽  
Vol 113 (6) ◽  
pp. 1492-1497 ◽  
Author(s):  
Ichiro Inoue ◽  
Yuichi Inubushi ◽  
Takahiro Sato ◽  
Kensuke Tono ◽  
Tetsuo Katayama ◽  
...  
Keyword(s):  
Single Molecule ◽  
Structure Determination ◽  
Bragg Reflection ◽  
Atomic Displacement ◽  
High Energy ◽  
Pump Probe ◽  
X Ray ◽  
Enhanced Resolution ◽  
Damage Processes

Resolution in the X-ray structure determination of noncrystalline samples has been limited to several tens of nanometers, because deep X-ray irradiation required for enhanced resolution causes radiation damage to samples. However, theoretical studies predict that the femtosecond (fs) durations of X-ray free-electron laser (XFEL) pulses make it possible to record scattering signals before the initiation of X-ray damage processes; thus, an ultraintense X-ray beam can be used beyond the conventional limit of radiation dose. Here, we verify this scenario by directly observing femtosecond X-ray damage processes in diamond irradiated with extraordinarily intense (∼1019 W/cm2) XFEL pulses. An X-ray pump–probe diffraction scheme was developed in this study; tightly focused double–5-fs XFEL pulses with time separations ranging from sub-fs to 80 fs were used to excite (i.e., pump) the diamond and characterize (i.e., probe) the temporal changes of the crystalline structures through Bragg reflection. It was found that the pump and probe diffraction intensities remain almost constant for shorter time separations of the double pulse, whereas the probe diffraction intensities decreased after 20 fs following pump pulse irradiation due to the X-ray–induced atomic displacement. This result indicates that sub-10-fs XFEL pulses enable conductions of damageless structural determinations and supports the validity of the theoretical predictions of ultraintense X-ray–matter interactions. The X-ray pump–probe scheme demonstrated here would be effective for understanding ultraintense X-ray–matter interactions, which will greatly stimulate advanced XFEL applications, such as atomic structure determination of a single molecule and generation of exotic matters with high energy densities.

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