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931.
Derk Brouwer Birgit van Duuren-Stuurman Markus Berges Elzbieta Jankowska Delphine Bard Dave Mark 《Journal of nanoparticle research》2009,11(8):1867-1881
In the past few years, an increasing number of studies on workplace air measurements on manufactured nano-materials and -objects
have been published. Most of the studies had a more explorative character, so a direct interpretation to workers” exposure
for a given exposure situation, activity, or process is not a straight-forward process. In general, the studies use a quite
similar package of devices for near real-time monitoring of particle number- and mass concentration in size ranges <100 nm
up to 10 μm, and the collection of samples for off-line characterization of air samples. Various approaches for addressing
background concentrations and its use to indicate the potential for exposure to nano-objects could be observed. Within the
EU-sponsored NANOSH project, a harmonized approach for measurement strategy, data analysis and reporting was developed. In
addition to time/activity–concentration profiles as reported by most studies, this approach enables a first step to estimate
the potential for exposure to manufactured nano-objects, more quantitatively. The NANOSH data will be collated into a base,
which may form the starting point for a harmonized database facilitating overall analysis in near future, to derive estimates
for exposure for several exposure situations. 相似文献
932.
Results are given of Zeeman and microwave induced delayed phosphorescence experiments which determine the relative activities of the three zero-field spin components in the phosphorescence of benzene. The results allow one to decide which of the mechanisms proposed by Albrecht are responsible for the intensity of some of the most prominent bands in the phosphorescence spectrum. It is confirmed that vibronic coupling in the triplet manifold plays the dominant role for the phosphorescence bands that involve e 2g vibrations and it follows that the phosphorescence in these bands is almost purely out-of-plane polarized. Our results indicate that spin-orbit coupling occurs via the same mechanism as in other aromatic hydrocarbons. 相似文献
933.
934.
Multiscale Approach to the Study of the Electronic Properties of Two Thiophene Curcuminoid Molecules
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Alvaro Etcheverry‐Berríos Ignacio Olavarría Dr. Mickael L. Perrin Raúl Díaz‐Torres Domingo Jullian Dr. Ingrid Ponce Dr. José H. Zagal Dr. Jorge Pavez Dr. Sergio O. Vásquez Dr. Herre S. J. van der Zant Dr. Diana Dulić Dr. Núria Aliaga‐Alcalde Dr. Monica Soler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(36):12808-12818
We studied the electronic and conductance properties of two thiophene–curcuminoid molecules, 2‐thphCCM ( 1 ) and 3‐thphCCM ( 2 ), in which the only structural difference is the position of the sulfur atoms in the thiophene terminal groups. We used electrochemical techniques as well as UV/Vis absorption studies to obtain the values of the HOMO–LUMO band gap energies, showing that molecule 1 has lower values than 2 . Theoretical calculations show the same trend. Self‐assembled monolayers (SAMs) of these molecules were studied by using electrochemistry, showing that the interaction with gold reduces drastically the HOMO–LUMO gap in both molecules to almost the same value. Single‐molecule conductance measurements show that molecule 2 has two different conductance values, whereas molecule 1 exhibits only one. Based on theoretical calculations, we conclude that the lowest conductance value, similar in both molecules, corresponds to a van der Waals interaction between the thiophene ring and the electrodes. The one order of magnitude higher conductance value for molecule 2 corresponds to a coordinate (dative covalent) interaction between the sulfur atoms and the gold electrodes. 相似文献
935.
Dr. Jingjun Hao Prof. Arnold L. Rheingold Marzieh Kavand Dr. Kipp J. van Schooten Prof. Christoph Boehme Dr. Marçal Capdevila‐Cortada Prof. Juan J. Novoa Eva Wöss Prof. Günther Knör Prof. Joel S. Miller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(35):12312-12315
The reaction of 2,3,5,6‐tetracyanopyridine (TCNPy) and Cr(C6H6)2 forms diamagnetic σ‐[TCNPy]22? possessing a 1.572(3) Å intrafragment sp3–sp3 bond. This is in contrast to the structurally related 1,2,4,5‐tetracyanobenzene and 1,2,4,5‐tetracyanopyrazine that form π‐dimer dianions possessing long, multicenter bonds. 相似文献
936.
Back Cover: Experimental and Theoretical Study of the Reactivity of Gold Nanoparticles Towards Benzimidazole‐2‐ylidene Ligands (Chem. Eur. J. 30/2016)
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Dr. María Rodríguez‐Castillo Gustavo Lugo‐Preciado Dr. Danielle Laurencin Dr. Frederik Tielens Dr. Arie van der Lee Dr. Sébastien Clément Dr. Yannick Guari Dr. José M. López‐de‐Luzuriaga Dr. Miguel Monge Dr. Françoise Remacle Dr. Sébastien Richeter 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(30):10680-10680
937.
Results of further calculations on the dynamic coupling between the lower B 1u and E 1u electronic states of benzene via a single e 2g mode are presented. In part I we gave the ‘pseudo-cylindrical’ solutions that result when the leading coupling term, linear in the nuclear displacements, is considered (cylindrical Born-Oppenheimer potential). Here we investigate the effect of 1. (1) the next higher terms in the expansion of the coupling hamiltonian for the free molecule (hexagonal Born-Oppenheimer potential); 2. (2) a crystal field anisotropy. From the scanty data on the coupling constants available a priori it would follow that the refinement introduced by (1) is small for benzene. On the contrary, the effect of even a small crystal field anisotropy is predicted to be appreciable. The results of the calculations are analysed by comparison with experimental data on the benzene crystal at low temperature. A consistent interpretation of both magnetic resonance results and the triplet ← singlet absorption spectrum is obtained. 相似文献
938.
Virginie Aumond Matthieu Waeles Pascal Salaün Kristoff Gibbon-Walsh Constant M.G. van den Berg Pierre-Marie Sarradin Ricardo D. Riso 《Analytica chimica acta》2012
A rapid electrochemical stripping chronopotentiometric procedure to determined sulfide in unaltered hydrothermal seawater samples is presented. Sulfide is deposited at −0.25 V (vs Ag/AgCl, KCl 3 M) at a vibrating gold microwire and then stripped through the application of a reductive constant current (typically −2 μA). The hydrodynamic conditions are modulated by vibration allowing a short deposition step, which is shown here to be necessary to minimize H2S volatilization. The limit of detection (LOD) is 30 nM after a deposition step of 7 s. This LOD is in the same range as the most sensitive cathodic voltammetric technique using a mercury drop electrode and is well below those reported previously for other electrodes capable of being implemented in situ. 相似文献
939.
We comment on the paper [Song et al., J. Comput. Chem. 2009, 30, 399]. and discuss the efficiency of the orbital optimization and gradient evaluation in the Valence Bond Self Consistent Field (VBSCF) method. We note that Song et al. neglect to properly reference Broer et al., who published an algorithm [Broer and Nieuwpoort, Theor. Chim. Acta 1988, 73, 405] to use a Fock matrix to compute a matrix element between two different determinants, which can be used for an orbital optimization. Further, Song et al. publish a misleading comparison with our VBSCF algorithm [Dijkstra and van Lenthe, J. Chem. Phys. 2000, 113, 2100; van Lenthe et al., Mol. Phys. 1991, 73, 1159] to enable them to favorably compare their algorithm with ours. We give detail timings in terms of different orbital types in the calculation and actual timings for the example cases. © 2012 Wiley Periodicals, Inc. 相似文献
940.