169 research outputs found
Novel neutral iron(II) isocyanide maleonitrile dithiolate [Fe(S2C2(CN)2)(t-BuNC) 4] compound
FeBr2 reacts with the S2C2(CN)2(2-) ion (1:1 ratio) in the presence of an excess of t-BuNC in THF to give the mixed ligand [Fe(S2C2(CN)2)(t-BuNC) 4] compound. This neutral product with a formal oxidation state of two for the iron atom was characterized by conductivity measurements, and, i.r., Mössbauer, 13C and ÂčH n.m.r. spectroscopy. There is a Fe-C pi back-donation strengthened towards isocyanide ligands, according to the data of 13C, ÂčH n.m.r. and Mössbauer spectroscopy.7678Conselho Nacional de Desenvolvimento CientĂfico e TecnolĂłgico (CNPq
Novel neutral iron(II) isocyanide maleonitrile dithiolate [Fe(S2C2(CN)2)(t-BuNC) 4] compound
A singleâsynapse resolution survey of PSD95âpositive synapses in twenty human brain regions
Enhancement of the Electron Spin Resonance of Single-Walled Carbon Nanotubes by Oxygen Removal
We have observed a nearly fourfold increase in the electron spin resonance
(ESR) signal from an ensemble of single-walled carbon nanotubes (SWCNTs) due to
oxygen desorption. By performing temperature-dependent ESR spectroscopy both
before and after thermal annealing, we found that the ESR in SWCNTs can be
reversibly altered via the molecular oxygen content in the samples. Independent
of the presence of adsorbed oxygen, a Curie-law (spin susceptibility ) is seen from 4 K to 300 K, indicating that the probed spins are
finite-level species. For both the pre-annealed and post-annealed sample
conditions, the ESR linewidth decreased as the temperature was increased, a
phenomenon we identify as motional narrowing. From the temperature dependence
of the linewidth, we extracted an estimate of the intertube hopping frequency;
for both sample conditions, we found this hopping frequency to be 100
GHz. Since the spin hopping frequency changes only slightly when oxygen is
desorbed, we conclude that only the spin susceptibility, not spin transport, is
affected by the presence of physisorbed molecular oxygen in SWCNT ensembles.
Surprisingly, no linewidth change is observed when the amount of oxygen in the
SWCNT sample is altered, contrary to other carbonaceous systems and certain 1D
conducting polymers. We hypothesize that physisorbed molecular oxygen acts as
an acceptor (-type), compensating the donor-like (-type) defects that are
responsible for the ESR signal in bulk SWCNTs.Comment: 14 pages, 7 figure
Thermal-equilibrium defects in undoped hydrogenated amorphous silicon, silicon-carbon, and silicon-nitrogen
Defect Creation by Optical Excitation in Hydrogenated Amorphous Silicon as Elucidated by Optically Detected Magnetic Resonance
Time-Resolved Optically Detected Magnetic Resonance Experiment on Conduction Band Tail Electrons and A
Resistivity Decrease Due to Electron Spin Resonance in the Metallic Region of Heavily Phosphorus-Doped Silicon
- âŠ