Search results for "ATOMS"

Single-molecule optical switching of terrylene in p-terphenyl

1997

The controlled manipulation and switching of single atoms and molecules raise the prospect of ultra-high-density data storage. Switching by motion of a single atom has been reported1, and techniques of single-molecule optical detection and spectroscopy2 in the condensed phase have been refined to a degree that allows the modification of the absorption properties of a single chromophore3. Light-induced jumps in single-molecule excitation frequencies have been reported3,4,5, but in none of these cases could the process be controlled: the jumps varied from molecule to molecule, they were interrupted by spontaneous jumps, and the new excitation frequencies could not be identified unambiguously.…

Theory of the Lamb Shift and fine structure in muonic 4He ions and the muonic 3He– 4He Isotope Shift

2018

Abstract We provide an up to date summary of the theory contributions to the 2S → 2P Lamb shift and the fine structure of the 2P state in the muonic helium ion ( μ 4 He ) + . This summary serves as the basis for the extraction of the alpha particle charge radius from the muonic helium Lamb shift measurements at the Paul Scherrer Institute, Switzerland. Individual theory contributions needed for a charge radius extraction are compared and compiled into a consistent summary. The influence of the alpha particle charge distribution on the elastic two-photon exchange is studied to take into account possible model-dependencies of the energy levels on the electric form factor of the nucleus. We al…

Transition state theory thermal rate constants and RRKM-based branching ratios for the N((2)D) + CH(4) reaction based on multi-state and multi-refere…

2012

International audience; Multireference single and double configuration interaction (MRCI) calculations including Davidson (+Q) or Pople (+P) corrections have been conducted in this work for the reactants, products, and extrema of the doublet ground state potential energy surface involved in the N(2D) + CH4 reaction. Such highly correlated ab initio calculations are then compared with previous PMP4, CCSD(T), W1, and DFT/B3LYP studies. Large relative differences are observed in particular for the transition state in the entrance channel resolving the disagreement between previous ab initio calculations. We confirm the existence of a small but positive potential barrier (3.86 +/- 0.84 kJ mol-1…

Ag44(SeR)30: A Hollow Cage Silver Cluster with Selenolate Protection.

2015

Selenolate protected, stable and atomically precise, hollow silver cluster was synthesized using solid state as well as solution state routes. The optical absorption spectrum shows multiple and sharp features similar to the thiolated Ag44 cluster, Ag44(SR)30 whose experimental structure was reported recently. High-resolution electrospray ionization mass spectrometry (HRESI MS) shows well-defined molecular ion features with two, three, and four ions with isotopic resolution, due to Ag44(SePh) 30. Additional characterization with diverse tools confirmed the composition. The closed-shell 18 electron superatom electronic structure, analogous to Ag44(SR)30 stabilizes the dodecahedral cage with a…

Nanorings driven by strong laser fields: dynamics and applications

Discerning the Origins of the Amplitude Fluctuations in Dynamic Raman Nanospectroscopy

2012

International audience; We introduce a novel experimental and analytical method for discerning rare surface-enhanced Raman scattering (SERS) events observable at the nanoscale. We show that the kinetics of the Raman activity recorded on an isolated nanostructure is punctuated by intense and rare events of large amplitude and spectral variations. The fluctuations of thousands of SERS spectra were analyzed statistically in terms of power density functions, and the occurrence of the rare events was quantified by a wavenumber statistics. Our analysis enables one to extract valuable and unique spectroscopic signature of Raman variations usually hidden in time-average or space-average measurement…

Evidence for a different electronic configuration as a primary effect during compression of orthorhombic perovskites: The case of NdM3+ O3 (M=Cr, Ga)

2018

(Mg,Fe)SiO3 perovskite is the most abundant mineral of the Earth's lower mantle, and compounds with the perovskite structure are perhaps the most widely employed ceramics. Hence, they attract both geophysicists and material scientists. Several investigations attempted to predict their structural evolution at high pressure, and recent advancements highlighted that perovskites having ions with the same formal valence at both polyhedral sites (i.e., 3+:3+) define different compressional patterns when transition metal ions (TMI) are involved. In this study, in situ high-pressure synchrotron XRD measurements coupled with ab initio simulations of the electronic population of NdCrO3 perovskite are…

Polynitrile anions as ligands: Synthesis, structure and magnetic properties of a new three-dimensional coordination polymer with the 2-dicyanomethyle…

2005

cited By 12; International audience; Reaction between CuCl2 and K2tcpd (tcpd2- = C[C(CN)2]32- = 2-dicyanomethylenc-1,1,3,3-tetracyanopropanediide anion) in presence of the neutral ligand tn (1,3-diaminopropane) in aqueous solution yields the new compound [Cu(tn)(tcpd)] (1) which was characterized by X-ray crystallography. The crystal structure of 1 consists of one [Cu(tn)]2+ unit and one tcpd2- anion, both located on general positions. Each Cu atom presents an essentially octahedral coordination with four nitrogen atoms arising from four polynitrile ligands and two nitrogen atoms from the chelating tn ligand. Despite its six nitrile groups potentially bridging, the tcpd ligand acts with a μ…

Charged kaon production by coherent scattering of neutrinos and antineutrinos on nuclei

2013

With the aim of achieving a better and more complete understanding of neutrino interactions with nuclear targets, the coherent production of charged kaons induced by neutrinos and antineutrinos is investigated in the energy range of some of the current neutrino experiments. We follow a microscopic approach which, at the nucleon level, incorporates the most important mechanisms allowed by the chiral-symmetry-breaking pattern of QCD. The distortion of the outgoing K ((K) over bar) is taken into account by solving the Klein-Gordon equation with realistic optical potentials. Angular and momentum distributions, as well as the energy and nuclear dependence of the total cross section, are studied.

Entanglement control via reservoir engineering in ultracold atomic gases

2013

We study the entanglement of two impurity qubits immersed in a Bose-Einstein condensate (BEC) reservoir. This open quantum system is particularly interesting because the reservoir and system parameters are easily controllable and the reduced dynamics is highly non-Markovian. We show how the model allows for interpolation between a common dephasing scenario and an independent dephasing scenario by simply modifying the wavelength of the superlattice superposed to the BEC, and how this influences the dynamical properties of the impurities. We demonstrate the existence of very rich entanglement dynamics correspondent to different values of reservoir parameters, including phenomena such as entan…