spectroscopie laser dans l’infrarouge lointain, leurs longueurs d’onde citees dans la litterature etant erronees. Nous presentons egalement les mesures de 8 nouvelles raies que nous avons observees.
Electron paramagnetic resonance (EPR) spectroscopy interrogates unpaired electron spins in solids and liquids to reveal local structure and dynamics; for example, EPR has elucidated parts of the structure of protein complexes that have resisted all other techniques in structural biology. EPR can also probe the interplay of light and electricity in organic solar cells and light-emitting diodes, and the origin of decoherence in condensed matter, which is of fundamental importance to the development of quantum information processors. Like nuclear magnetic resonance (NMR), EPR spectroscopy becomes more powerful at high magnetic fields and frequencies, and with excitation by coherent pulses rather than continuous waves. However, the difficulty of generating sequences of powerful pulses at frequencies above 100 GHz has, until now, confined high-power pulsed EPR to magnetic fields of 3.5 T and below. Here we demonstrate that ~1 kW pulses from a free-electron laser (FEL) can power a pulsed EPR spectrometer at 240 GHz (8.5 T), providing transformative enhancements over the alternative, a state-of-the-art ~30 mW solid state source. Using the UC Santa Barbara FEL as a source, our 240 GHz spectrometer can rotate spin-1/2 electrons through pi/2 in only 6 ns (vs. 300 ns with the solid state source). Fourier transform EPR on nitrogen impurities in diamond demonstrates excitation and detection of EPR lines separated by ~200 MHz. Decoherence times for spin-1/2 systems as short as 63 ns are measured, enabling measurement of the decoherence time in a frozen solution of nitroxide free-radicals at temperatures as high as 190 K. Both FELs and the quasi-optical technology developed for the spectrometer are scalable to frequencies well in excess of 1 THz, opening the possibility of high-power pulsed EPR spectroscopy up to the highest static magnetic fields on earth.
We report a temperature and frequency dependent electron spin resonance (ESR) study of the kagomé spin-1/2 compound ZnCu3(OH)6Cl2. Our results demonstrate that two spin species are simultaneously detected; copper spins on the intra-plane Cu2+ kagomé sites and those on the inter-plane Zn2+ sites, the latter resulting from the Cu2+/Zn2+ antisite disorder. We examine all the possible magnetic anisotropy terms, which could lead to the observed extremely broad ESR lines in this system. We argue that the line broadening is due to Dzyaloshinsky-Moriya interaction.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Abstract The cyclotron resonance and electron spin resonance of n‐InSb under hydrostatic pressure up to 1 GPa are investigated using photoconductivity techniques. All the transitions observed are fitted using a modified Pidgeon‐Brown model with a set of band parameters recently proposed by Goodwin and Seiler and a change of the band gap of d E g /d P = (0.140 ± 0.004) meV/MPa, a value in good agreement with experimental results.
Reflectivity measurements, at different fixed frequencies, have been performed on ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{CaCu}}_{2}$${\mathrm{O}}_{8}$ films as a function of temperature and magnetic field. Analysis of the data provides evidence for an order parameter 2\ensuremath{\Delta}(0)\ensuremath{\simeq}3.3${\mathit{k}}_{\mathit{B}}$${\mathit{T}}_{\mathit{c}}$ although the variation of this order parameter with temperature is significantly different from that predicted by the weak-coupling BCS model.
