Solvation dynamics monitored by combined X-ray spectroscopies and scattering: photoinduced spin transition in aqueous [Fe(bpy)3]2+

2014 ◽  
Vol 171 ◽  
pp. 169-178 ◽  
Author(s):  
C. Bressler ◽  
W. Gawelda ◽  
A. Galler ◽  
M. M. Nielsen ◽  
V. Sundström ◽  
...  
Keyword(s):  
Time Resolution ◽  
Time Scale ◽  
Spin Transition ◽  
Solvation Shell ◽  
Precise Determination ◽  
Heating Process ◽  
Solvation Dynamics ◽  
X Ray ◽  
Structure Changes

We have studied the photoinduced low spin (LS) to high spin (HS) conversion of aqueous Fe(bpy)3 with pulse-limited time resolution. In a combined setup permitting simultaneous X-ray diffuse scattering (XDS) and spectroscopic measurements at a MHz repetition rate we have unraveled the interplay between intramolecular dynamics and the intermolecular caging solvent response with 100 ps time resolution. On this time scale the ultrafast spin transition including intramolecular geometric structure changes as well as the concomitant bulk solvent heating process due to energy dissipation from the excited HS molecule are long completed. The heating is nevertheless observed to further increase due to the excess energy between HS and LS states released on a subnanosecond time scale. The analysis of the spectroscopic data allows precise determination of the excited population which efficiently reduces the number of free parameters in the XDS analysis, and both combined permit extraction of information about the structural dynamics of the first solvation shell.

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.

Intraoperative Determination of the Extent of Corpus Callosotomy for Epilepsy: Two Simple Techniques

Neurosurgery ◽  
1990 ◽  
Vol 26 (1) ◽  
pp. 102-106 ◽  
Author(s):  
Issam A. Awad ◽  
Elaine Wyllie ◽  
Hans Luders ◽  
Jennifer Ahl
Keyword(s):  
Corpus Callosum ◽  
Precise Determination ◽  
Planar Geometry ◽  
Corpus Callosotomy ◽  
Midsagittal Plane ◽  
Anatomic Landmarks ◽  
Mri Scan ◽  
Simple Modification ◽  
X Ray

Abstract There is increasing interest in staged corpus callosotomy for intractable generalized epilepsy. At the first procedure, a portion (usually the anterior two-thirds) of the corpus callosum is sectioned. If seizures persist, completion of callosotomy or alternative treatment approaches can be considered. It is obviously important to ascertain that the desired extent of callosotomy was in fact accomplished at the time of initial operation. Our experience and the published literature indicate that the surgeon's impression at operation can be erroneous. We describe a technique of determining extent of corpus callosotomy during the procedure. The magnetic resonance imaging (MRI) scan in the midsagittal plane is used to select the desired extent of callosotomy. That point on the corpus callosum is characterized using simple planar geometry in relation to three anatomic landmarks in that same plane: the glabella, the inion, and the bregma (midline intersection of the coronal suture). The same point along the corpus callosum can then be located on a lateral skull xray using these same three anatomic landmarks. At surgery, an intraoperative lateral skull x-ray is obtained with a marking clip, thereby verifying the actual extent of callosotomy. We have verified the reliability of this scheme in 5 callosotomy procedures and have used this technique for intraoperative localization of midline and parasagittal targets in another 7 cases (3 tumors, 2 aneurysms, and 2 placements of interhemispheric subdural grids). In addition, we reviewed corpus callosum topography on 25 randomly selected MRI scans. A perpendicular line bisecting the glabellainion line intersects the corpus callosum at a point near its two-thirds extent in every case. This allows a quick determination of the approximate two-thirds point along the corpus callosum by skull x-ray alone, without the need of an MRI scan. The use of the new technique and its simple modification for the two-thirds callosotomy allows a precise determination of the extent of corpus callosum section at surgery and should avoid unintended deviations from the desired procedure. (Neurosurgery 26:102-106, 1990)

Computer reconstructed X-ray imaging

1979 ◽  
Vol 292 (1390) ◽  
pp. 223-232 ◽  
Keyword(s):  
Spatial Resolution ◽  
Atomic Number ◽  
High Sensitivity ◽  
Precise Determination ◽  
Diagnostic Methods ◽  
X Ray ◽  
X Ray Imaging ◽  
Internal Structures ◽  
Transmission Measurements

Computed tomography is a method for obtaining a series of radiographic pictures of contiguous slices through a solid object such as the human body. Each picture is computed from a set of X-ray transmission measurements and represents the distribution of X-ray attenuation in the slice. The high sensitivity of the method to changes in both density and atomic number has resulted in the development of new diagnostic methods in medicine. The limitations of the method are discussed in terms of two particular kinds of application. First, those applications in which a very precise determination of density or atomic number is required, but at low spatial resolution; an example would be the determination of the uniformity of mixture of plastics or metals. The second kind of application is that requiring high spatial resolution as in the detection of cracks and the visualization of internal structures in complicated objects.

POSITRON FACILITIES TESTS OF THE X-RAYS PRODUCED BY CRYSTALLINE UNDULATORS

2005 ◽  
Vol 19 (03) ◽  
pp. 85-98 ◽  
Author(s):  
S. BELLUCCI
Keyword(s):  
Positron Beam ◽  
Precise Determination ◽  
X Rays ◽  
Experimental Conditions ◽  
X Ray ◽  
Accelerated Particles

One of the main involvements of the INFN-Laboratori Nazionali di Frascati group in channeling researches is described, i.e. the crystal undulator R & D, with the characterization of the crystal undulator prototypes with SEM and the positron beam. We consider a precise determination of the optimal experimental conditions for channeling of this kind of accelerated particles through such microstructured crystals, as promising candidates for producing X-ray beams.

Sign in / Sign up

Export Citation Format

Share Document