We have applied the method of foil-induced Coulomb Explosion Imaging (FCEI) to determine the handedness of a homochiral sample of the compound trans-2,3-dideuterooxirane C2OH2D2. We determined the compound to be of the (R, R)-econfiguration with a statistical significance of 5σ. As the molecular sample was chemically linked to the stereochemical reference standard glyceraldehyde, our assignment constitutes an independent verification of the absolute handedness of all compounds linked to this reference substance.

In electron-transfer processes, spin effects normally are seen either in magnetic materials or in systems containing heavy atoms that facilitate spin-orbit coupling. We report spin-selective transmission of electrons through self-assembled monolayers of double-stranded DNA on gold. By directly measuring the spin of the transmitted electrons with a Mott polarimeter, we found spin polarizations exceeding 60% at room temperature. The spin-polarized photoelectrons were observed even when the photoelectrons were generated with unpolarized light. The observed spin selectivity at room temperature was extremely high as compared with other known spin filters. The spin filtration efficiency depended on the length of the DNA in the monolayer and its organization.

The possibility of having silicon with magnetic properties ignites the imagination, because the combination of the electronic properties of silicon with magnetic response seems as an ideal approach towards spin-dependent electronics: Spin-tronics. [1,2] Here we present evidence that silicon possesses appreciable magnetic properties when its surfaces are treated in a special way and an oxide layer is formed. We have found a clear relation between the nature of the surface roughness of the silicon samples and the measured magnetism. The magnetism observed is temperature-independent up to room temperature.

A Comment on the Letter by Zeev Vager and Ron Naaman, Phys. Rev. Lett. 92, 087205 (2004). The authors of the Letter offer a Reply.Received 8 August 2005DOI:https://doi.org/10.1103/PhysRevLett.96.029703©2006 American Physical Society

Here we show that self-assembled monolayers on gold of double-stranded DNA oligomers interact with polarized electrons similarly to a strong and oriented magnetic field. The direction of the field for right-handed DNA is away from the substrate. Moreover, the layer shows very high paramagnetic susceptibility. Interestingly, thiolated single-stranded DNA oligomers on gold do not show this effect. The new findings are rationalized based on recent results in which high paramagnetism was measured for diamagnetic films adsorbed on diamagnetic substrates.

New electronic and magnetic properties are induced by the adsorption of closed packed monolayers on solid substrates. For many thiolated molecules self-assembled on gold, a surprisingly large paramagnetism is observed. In the case where the layers are made from chiral molecules, in addition an unexpectedly large electronic dichroism is observed, which manifests itself as spin specific electron transmission. This dichroism was observed for monolayers made from polyalanine and from DNA. Self-assembled monolayers of double-stranded DNA oligomers on gold interact with polarized electrons similarly to a strong and oriented magnetic field. The direction of the field for right-handed DNA is away from the substrate. Moreover, the layer shows very high paramagnetic susceptibility. Interestingly, thiolated single-stranded DNA oligomers on gold do not show this effect. All the observations can be rationalized by assuming organization induced charge transfer between the substrate and the organic layer. The charge transfer results in spin alignment of the transferred electrons/holes. While for achiral molecules the spin alignment varies among the domains, in the case of monolayer made from chiral molecules the alignment is the same across the entire sample. When magnetic field is applied, large magnetic moment is observed that results from orbital magnetism.

Two‐dimensional arrangements of molecules can show remarkable cooperative electronic effects. Such effects can serve to achieve direct electronic sensing of chemical and physical processes via electrostatic effects, i.e., without transfer of charge or matter between the locus of sensing and that of detection.

Recently, unusual giant magnetic properties were found experimentally in some organized organic monolayers adsorbed on solid substrates. A model is presented which explains the observed phenomenon. The model is based on the special properties of electrons transferred from the substrate to the layer as a result of the adsorption process. Triplet pairing of those electrons is forced by the special 2D properties of the organic layer. Such pairs are confined within domains in the organic layer and their quantum statistics provide a model that explains the unique magnetization as well as all other features of the experimental observations. The model suggests the possible existence of Bose-Einstein condensation at room temperature on the scale of the domains.

The effect of target polarization fields on the bond-angle distribution following the foil-induced Coulomb explosion of CH2+ has been measured. Incorporating a detailed model description of the polarization effects and other target effects into a Monte Carlo simulation of the experiment, a good description of the various observables is obtained. In particular, the bond-angle distribution is found to agree with existing ab initio calculations.

The most probable structure of protonated acetylene C2H3+ (the "vinyl cation") is inferred from both Coulomb-explosion experiments and finite-temperature ab initio quantum simulations followed by simulations of foil effects. It is found that C2H3+ features significant deviations from the planar bridged equilibrium structure as well as from the planar Y-shaped local minimum structure, which are known from static electronic structure calculations. In particular, the "axial protons" feature a significant out-of-plane trans-bending due to fluctuation effects. This implies that the nonplanarity has to be taken into account in theoretical treatments that aim at describing this fluxional molecule.

Unique occurrence of magnetism is shown, in which magnetism appears ex nihilo, when organic molecules are self-assembled as monolayers on gold substrate. The molecules as well as the substrate, when they stand alone, are diamagnetic. Using a superconducting quantum interference device type magnetometer we obtained direct evidence that close-packed organized thio-organic films adsorbed on gold substrates possess magnetic properties at room temperature. The films studied show very high specific magnetization, up to many tens Bohr magnetons per adsorbed molecule, with a very small hysteresis. It is highly anisotropic and shows almost no temperature dependence. The magnetism observed is related to charge transfer between the organic layer and the metal substrate. Yet, the uniqueness here is that many spins are polarized per adsorbed molecules. The magnetic effect is related to the two dimensional organization of the organic molecules on the metal substrate which might explain the high anisotropy.

A model is given that shows that the electronic properties of close packed organized organic layers, adsorbed on conductive substrate, may be very different from the properties of the single adsorbed molecule. The difference arises from a cooperative effect that results in electron transfer between the substrate and the layer. It is induced when molecules having dipole moment and low polarizability are organized so that their dipole moment is perpendicular to the surface. The thermodynamics of the problem is described. The model provides a possible rationalization to recent observed new experimental properties of adsorbed organized organic layers.

New electronic and magnetic properties are induced by the adsorption of close-packed monolayers of thiols on gold. In layers made from chiral molecules, unexpectedly large electronic dichroism is observed, which manifests itself as spin-specific electron transmission. For many thiolated molecules self-assembled on gold, a surprisingly large ferromagnetism is observed. All the observations can be rationalized by assuming orbital ferromagnetism of the organic thin layer. This is a new type of magnetism, induced by the formation of a closed packed layer of organic molecules on metal. The adsorption results in charge transfer between the substrate and the adsorbed layer, which is the origin of this magnetism.

Vibrational relaxation and isomerization of internally excited deuterated formyl and isoformyl cations has been investigated on the time scale of 2 ms to 12 s using the nearly interaction-free environment of an ion storage ring. De-excitation of the v2 bending modes of DCO+ and DOC+ due to spontaneous radiative transitions was observed as a function of the storage time by measuring their foil-induced Coulomb explosion using three-dimensional coincident fragment imaging. No isomerization of low-lying vibrational levels of DOC+ ions was observed on the time scales considered. By comparing the Coulomb explosion data to molecular bond angle distributions obtained from vibrational wave function calculations, the time evolution of the mean v2 population is deduced for both isomers. The stored DOC+ ions are found to thermalize with the 300 K black-body radiation, while relaxation of the DCO+ bending vibrations was found to require considerably longer times, in agreement with a predicted very small transition moment of the v2=1 level.

Angewandte Chemie International EditionVolume 41, Issue 5 p. 761-764 Communication Magnetization of Chiral Monolayers of Polypeptide: A Possible Source of Magnetism in Some Biological Membranes Itai Carmeli, Itai Carmeli Department of Chemical Physics Weizmann Institute of Science Rehovot 76100 (Israel) Fax: (+972) 8-9344123Search for more papers by this authorViera Skakalova Dr., Viera Skakalova Dr. Department of Chemical Physics Weizmann Institute of Science Rehovot 76100 (Israel) Fax: (+972) 8-9344123Search for more papers by this authorRon Naaman Prof., Ron Naaman Prof. ron.naaman@weizmann.ac.il Department of Chemical Physics Weizmann Institute of Science Rehovot 76100 (Israel) Fax: (+972) 8-9344123Search for more papers by this authorZeev Vager Prof., Zeev Vager Prof. Department of Chemical Physics Weizmann Institute of Science Rehovot 76100 (Israel) Fax: (+972) 8-9344123Search for more papers by this author Itai Carmeli, Itai Carmeli Department of Chemical Physics Weizmann Institute of Science Rehovot 76100 (Israel) Fax: (+972) 8-9344123Search for more papers by this authorViera Skakalova Dr., Viera Skakalova Dr. Department of Chemical Physics Weizmann Institute of Science Rehovot 76100 (Israel) Fax: (+972) 8-9344123Search for more papers by this authorRon Naaman Prof., Ron Naaman Prof. ron.naaman@weizmann.ac.il Department of Chemical Physics Weizmann Institute of Science Rehovot 76100 (Israel) Fax: (+972) 8-9344123Search for more papers by this authorZeev Vager Prof., Zeev Vager Prof. Department of Chemical Physics Weizmann Institute of Science Rehovot 76100 (Israel) Fax: (+972) 8-9344123Search for more papers by this author First published: 07 March 2002 https://doi.org/10.1002/1521-3773(20020301)41:5<761::AID-ANIE761>3.0.CO;2-ZCitations: 48 We are grateful to Prof. M. Fridkin and his group for helping us in the synthesis of the polyalanine. Partial support from the US–Israel Binational Science Foundation is acknowledged. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract α-Helical l- and D-polyalanines have magnetic properties when self-assembled as monolayers on gold surfaces. The properties depend on the chirality of the molecules and on the direction of their dipole moment relative to the substrate. They were investigated by IR spectroscopy, which determined the orientation of the molecules relative to the surface in the presence of a magnetic field, and by measuring the spin selectivity for electron transmission through the layers. Citing Literature Volume41, Issue5March 1, 2002Pages 761-764 RelatedInformation

The vibrational relaxation of H-3(+) molecules from a conventional plasma ion source is studied performing Coulomb explosion imaging on the ions extracted from a storage ring after variable times of storage. Storage for 2 s is found sufficient for radiative relaxation of the breathing excitation and the fragment velocity distribution in the breathing coordinate then agrees well with simulations based on the calculated ground-state wave function. The radiative decay of the two lowest pure breathing levels (1,0(0)) and (2,0(0)) is seen to be considerably faster than expected from rotationless calculations. Assuming a high rotational excitation of the H-3(+) ions, as suggested already in earlier experiments, the theoretical transition probabilities of the University College London line list for H-3(+) [L. Neale, S. Miller, and J. Tennyson, Astrophys. J. 464, 516 (1996)] can explain the increase of the vibrational cooling rates and reproduce the observed decay curve for the lowest breathing-excited level, confirming the absolute transition probabilities of these line tables. The observations give evidence for a quasistable population of high-lying rotational levels in the stored ion beam, relevant for the interpretation of storage ring measurements on the rate coefficients for dissociative recombination of H-3(+) ions with low-energy electrons.

Close-packed organized organic monolayers are finding their place in many applications and specifically in molecular electronic related functions. As a result, the relation between the properties of the single molecule and of the molecule imbedded within the monolayer is of importance. Here it is shown that upon formation of the layer the molecular electric dipole is reduced and is independent of the free molecules' electric dipole. Its upper bound value is derived from the thin film property of dielectric breakdown. Moreover, when the molecules in the layer are homochiral, the monolayer may have appreciable magnetic properties.

Measurements of the spin-correlated transmission of electrons through organized monolayers of polypeptide helices, absorbed on gold substrate, show high spin selectivity. The direction of the magnetic moment of the layer depends on the handedness of the helix molecule and on the direction of their dipole moment with respect to the metal substrate.

D. Strasser,1 L. Lammich,2 S. Krohn,1 M. Lange,2 H. Kreckel,2 J. Levin,2 D. Schwalm,2 Z. Vager,1 R. Wester,2 A. Wolf,2 and D. Zajfman1,* 1Department of Particle Physics, Weizmann Institute of Science, Rehovot, 76100, Israel 2Max-Planck-Institut für Kernphysik and Physikalisches Institut der Universität Heidelberg, D-69029 Heidelberg, Germany (Received 10 July 2000) Fragmentation patterns for dissociative recombination of the triatomic hydrogen molecular ion H 1 3 in the vibrational ground state have been measured using the storage ring technique and molecular fragment imaging. A broad distribution of vibrational states in the H2 fragment after two-body dissociation and a large predominance of nearly linear momentum geometries after three-body dissociation are found. The fragmentation results are directly contrasted with Coulomb explosion imaging data on the initial H 1 3 geometry, compared to existing wave-packet calculations, and considered in the light of a simple physical picture.

Fragmentation patterns for dissociative recombination of the triatomic hydrogen molecular ion H(3)(+) in the vibrational ground state have been measured using the storage ring technique and molecular fragment imaging. A broad distribution of vibrational states in the H(2) fragment after two-body dissociation and a large predominance of nearly linear momentum geometries after three-body dissociation are found. The fragmentation results are directly contrasted with Coulomb explosion imaging data on the initial H(3)(+) geometry, compared to existing wave-packet calculations, and considered in the light of a simple physical picture.