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1.
R. Schulé A. Steinhauser H. Stafast K. Bethge 《Zeitschrift für Physik A Hadrons and Nuclei》1978,287(3-4):343-347
Neon ions in either their ground state or an excited state collide with the molecules of an N2 gas-target. The collisional configuration-rearrangement is observed from theK- x-ray spectrum. A multistate model allowing for population and depopulation of the excited states with equal strength describes qualitatively the x-ray yield as a function of the target pressure. 相似文献
2.
I. Tserruya R. Schulé H. Schmidt-B?cking K. Bethge 《Zeitschrift für Physik A Hadrons and Nuclei》1976,89(1):233-241
TheK-shell ionization cross sections of Mn, Ni, Cu, Zn and Ge under32S bombardment have been measured in the energy range from 5 to 48 MeV. The cross sections are compared with available theories based on a direct Coulomb ionization mechanism and with the predictions of theK-vacancy sharing process. This last process can reasonably account for the measured cross sections at high bombarding energies. The energy shifts of theK
- andK
-lines and theK
/K
-intensity ratios have also been measured. This information is used to deduce the defect configuration of the atoms. The mechanisms responsible for the multiple vacancy production are discussed. 相似文献
3.
H. Schmidt-Böcking R. Schuch I. Tserruya R. Schulé H. J. Specht K. Bethge 《Zeitschrift für Physik A Hadrons and Nuclei》1978,284(1):39-42
Absolute differential cross sections of non-characteristic radiation emitted in energetic heavy-ion collisions (E P =3.92–48 MeV,Z=11–22) can only be explained in the framework of quasimolecular radiation. All other processes, particularly bremsstrahlung mechanisms are found to be negligible. For high projectile and photon energies the one-step quasimolecular radiation is dominant in solid targets, whereas the two-step process contributes mainly at low projectile and photon energies. 相似文献
4.
Amit Kumar Trevor Janes Subrata Chakraborty Prosenjit Daw Niklas vonWolff Raanan Carmieli Yael Diskin‐Posner David Milstein 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(11):3411-3415
We report a C?C bond‐forming reaction between benzyl alcohols and alkynes in the presence of a catalytic amount of KOtBu to form α‐alkylated ketones in which the C=O group is located on the side derived from the alcohol. The reaction proceeds under thermal conditions (125 °C) and produces no waste, making the reaction highly atom efficient, environmentally benign, and sustainable. Based on our mechanistic investigations, we propose that the reaction proceeds through radical pathways. 相似文献
5.
Omer Lustgarten Raanan Carmieli Leila Motiei David Margulies 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(1):190-194
A method for implementing a secret sharing scheme at the molecular level is presented. By creating molecular code generators that are self‐assembled from several molecular components, we established a means for distributing distinct code‐activating elements among several participants. In this way, an authorization code can only be generated when all the participants are present, which ensures that highly secured systems cannot be operated by unauthorized individuals or disloyal users. Additional layers of protection result from the ability to program the security code by replacing one or several molecular components and by subjecting the system to distinct chemical inputs. 相似文献
6.
7.
Or Dishi Yuval Rahav Dr. Raanan Carmieli Prof. Ori Gidron 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(62):e202202082
Macrocyclic furans are predicted to switch between global aromaticity and antiaromaticity, depending on their oxidation states. However, the macrocyclic furans reported to date are stabilized by electron withdrawing groups, which result in inaccessible oxidation states. To circumvent this problem, a post-macrocyclization approach was applied to introduce methylene-substituted macrocyclic furans, which display an extremely low oxidation potential of −0.23 vs. Fc/Fc+, and are partially oxidized in ambient conditions. Additional oxidation to the dication results in aromaticity switching to a global 30πe− aromatic state, as indicated by the formation of a strong diatropic current observed in the 1H NMR spectrum. NICS and ACID calculations support this trend and provide evidence for a different pathway for the global current in the neutral and dicationic states. According to these findings, macrocyclic furans can be rendered as promising p-type materials with stable oxidation states. 相似文献
8.
The population of excited states of neon projectiles has been deduced from highresolution x-ray spectra. From the comparison of the satellite and the hypersatellite spectrum we conclude that the population of the outer shells is insensitive to the presence of either one or twoK-shell vacancies. On the basis of a model of independent electrons the population distribution including states with filledK-shell can be estimated. The deduced mean charge states compare rather well with results obtained from beam analysis over a projectile energy range from 5 to 18 MeV. 相似文献
9.
Electrochemical Hydroxylation of Arenes Catalyzed by a Keggin Polyoxometalate with a Cobalt(IV) Heteroatom 下载免费PDF全文
Dr. Alexander M. Khenkin Miriam Somekh Dr. Raanan Carmieli Prof. Dr. Ronny Neumann 《Angewandte Chemie (International ed. in English)》2018,57(19):5403-5407
The sustainable, selective direct hydroxylation of arenes, such as benzene to phenol, is an important research challenge. An electrocatalytic transformation using formic acid to oxidize benzene and its halogenated derivatives to selectively yield aryl formates, which are easily hydrolyzed by water to yield the corresponding phenols, is presented. The formylation reaction occurs on a Pt anode in the presence of [CoIIIW12O40]5? as a catalyst and lithium formate as an electrolyte via formation of a formyloxyl radical as the reactive species, which was trapped by a BMPO spin trap and identified by EPR. Hydrogen was formed at the Pt cathode. The sum transformation is ArH+H2O→ArOH+H2. Non‐optimized reaction conditions showed a Faradaic efficiency of 75 % and selective formation of the mono‐oxidized product in a 35 % yield. Decomposition of formic acid into CO2 and H2 is a side‐reaction. 相似文献
10.
Z Zhu AC Fahrenbach H Li JC Barnes Z Liu SM Dyar H Zhang J Lei R Carmieli AA Sarjeant CL Stern MR Wasielewski JF Stoddart 《Journal of the American Chemical Society》2012,134(28):11709-11720
Two redox-active bistable [2]catenanes composed of macrocyclic polyethers of different sizes incorporating both electron-rich 1,5-dioxynaphthalene (DNP) and electron-deficient 4,4'-bipyridinium (BIPY(2+)) units, interlocked mechanically with the tetracationic cyclophane cyclobis(paraquat-p-phenylene) (CBPQT(4+)), were obtained by donor-acceptor template-directed syntheses in a threading-followed-by-cyclization protocol employing Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloadditions in the final mechanical-bond forming steps. These bistable [2]catenanes exemplify a design strategy for achieving redox-active switching between two translational isomers, which are driven (i) by donor-acceptor interactions between the CBPQT(4+) ring and DNP, or (ii) radical-radical interactions between CBPQT(2(?+)) and BIPY(?+), respectively. The switching processes, as well as the nature of the donor-acceptor interactions in the ground states and the radical-radical interactions in the reduced states, were investigated by single-crystal X-ray crystallography, dynamic (1)H NMR spectroscopy, cyclic voltammetry, UV/vis spectroelectrochemistry, and electron paramagnetic resonance (EPR) spectroscopy. The crystal structure of one of the [2]catenanes in its trisradical tricationic redox state provides direct evidence for the radical-radical interactions which drive the switching processes for these types of mechanically interlocked molecules (MIMs). Variable-temperature (1)H NMR spectroscopy reveals a degenerate rotational motion of the BIPY(2+) units in the CBPQT(4+) ring for both of the two [2]catenanes, that is governed by a free energy barrier of 14.4 kcal mol(-1) for the larger catenane and 17.0 kcal mol(-1) for the smaller one. Cyclic voltammetry provides evidence for the reversibility of the switching processes which occurs following a three-electron reduction of the three BIPY(2+) units to their radical cationic forms. UV/vis spectroscopy confirms that the processes driving the switching are (i) of the donor-acceptor type, by the observation of a 530 nm charge-transfer band in the ground state, and (ii) of the radical-radical ilk in the switched state as indicated by an intense visible absorption (ca. 530 nm) and near-infrared (ca. 1100 nm) bands. EPR spectroscopic data reveal that, in the switched state, the interacting BIPY(?+) radical cations are in a fast exchange regime. In general, the findings lay the foundations for future investigations where this radical-radical recognition motif is harnessed in bistable redox-active MIMs in order to achieve close to homogeneous populations of co-conformations in both the ground and switched states. 相似文献