Search results for "iTED"
showing 10 items of 2408 documents
Wavelength selective light-induced magnetic effects in the binuclear spin crossover compound{[Fe(bt)(NCS)2]2(bpym)}
2007
Using Fourier transform infrared spectroscopy, x-ray diffraction, and magnetic susceptibility measurements under light irradiation, the selective light-induced excited spin state trapping (LIESST) and the reversible-LIESST effect have been evidenced and studied in depth in the binuclear spin crossover compound {[Fe(bt)(NCS)2]2bpym}. In this system, each magnetic site can switch from low spin (LS) to high spin (HS), so that three states exist, namely, the LS-LS, HS-LS, and HS-HS. All these techniques shine a new light on the high phototunability of this system. In addition to the direct photoswitching from the LS-LS to the HS-LS or to the HS-HS state, here we show that photoinduced switching…
LRPH device optimization for axial and shear stresses
2020
The paper concerns an in-depth study of a special connection for steel structures and the formulation of the related optimal design problem. The connection is called Limited Resistance Rigid Perfectly Plastic Hinge (LRPH) and it represents an innovative device devoted to join steel beam elements of frame structures. The device consists in a sequence of steel cross sections constituted by two parallel flanges with suitably different thickness connected by as many webs with constant and equal thickness. The fundamental innovation of the device is the possibility of designing special connections with elastic stiffness and limit strength independent of each other. Such a special characteristic …
Photophysical and electroluminescence properties of bis(2′,6′-difluoro-2,3′-bipyridinato-N,C4′)iridium(picolinate) complexes: effect of electron-with…
2015
Herein, we have synthesized a series of 2′,6′-difluoro-2,3′-bipyridine cyclometalating ligands by substituting electron-withdrawing (–CHO, –CF3, and –CN) and electron-donating (–OMe and –NMe2) groups at the 4′ position of the pyridyl moiety and utilized them for the construction of five new iridium(III) complexes (Ir1–Ir5) in the presence of picolinate as an ancillary ligand. The photophysical properties of the developed iridium(III) compounds were investigated with a view to understand the substituent effects. The strong electron-withdrawing (–CN) group containing the iridium(III) compound (Ir3) exhibits highly efficient genuine green phosphorescence (λmax = 508 nm) at room temperature in …
Specific orientation of dipole moments in azocrown cetocyanine dyes determined by electrooptical absorption measurements (EOAM)
2019
Abstract From electrooptical absorption measurements (EOAM) follows that the dipole moments of azacrown ketocyanine dyes 2,5-di{(E)-1-[4-(4,7,10,13-tetraoxa-1-azacyclopentadecyl)phenyl]methylidene}-1-cyclopentanone (Compound 1) and (E)-1-(2-hydroxy-4methoxyphenyl)-3-[4-(4,7,10,13-tetraoxa-1-azacyclopentadecyl)phenyl]-2-propen-1-one (Compound 2) in the equilibrium ground state μg and the change of dipole moments upon transition to the excited Franck–Condon state Δaμ are large. This alteration causes a significant long-wavelength shift of the absorption and emission spectra, as well as large fluorescence Stokes shift with increasing polarity of the solvent. From the DFT calculations follows t…
Fascinating electronic games in iron complexes
1996
Coordination compounds of transition metal ions with open-shell electron configurations may exhibit dynamic electronic-structure phenomena, depending on the nature of the coordinating ligand sphere. The change of spin state with temperature («thermal spin-crossover»), light-induced electron transfer processes leading to long-lived metastable charge and spin states (e.g., «LIESST» effect), are some of the fascinating electronic games encountered in transition metal compounds, which are presently under extensive study by chemists and physicists. Mossbauer spectroscopy plays a dominant role in the investigation of such phenomena in iron compounds, as will be demonstrated in this paper. This wo…
ELECTRODEPOSITION OF NOVEL POLY(NAPHTHALENEDIIMIDE-QUATERTHIOPHENE) THIN FILMS AND APPLICATIONS IN PLASTIC OPTOELECTRONICS DEVICES
2013
A novel symmetric naphthalenediimide-quaterthiophene derivative (NDIT4d) has been polymerized on different substrates including glassy carbon and ITO/PET electrodes by means of electrochemical methods. XPS and UV-VIS spectroscopy as well as cyclic voltammetry have been employed for characterizing the thin film chemical features, the band gap and the HOMO and LUMO levels. DFT computational studies were in close agreement with the experimental observables also showing intriguing geometrical effects on the band gap energy values. The comparison of the energy levels locations of the electrodeposited poly(naphthalenediimide-quaterthiophene) derivative (e-PNDIT4) and P3HT thin films transferred b…
Axialisation, cooling and quenching of $\mathsf{Ba^+}$ ions in a Penning trap
1998
Collisions of ions, stored in a Penning trap, with neutral background molecules usually lead to rapid ion loss from the trap unless the ions are excited by the sum of the frequencies of the reduced cyclotron and magnetron motion. Then the ions are cooled by collisions and are driven to the trap centre leading to substantial increase of the storage time. Furthermore in a three level system including a long living metastable state collisions deexcite this metastable state and increase the population density in the ionic ground state. In a laser spectroscopic experiment we demonstrate the advantages of collisions on Ba+ ions stored in a Penning trap. The combined action of metastable state que…
Dark-Line Atomic Resonances in Micrometric Rb-Vapor Layer
2007
We present measurements of dark-line resonances excited in Rb atomic vapor confined in micrometric cells (MC). In our work, the Lambda-systems on D2 line of 85Rb have been studied with the use of bi-chromatic radiation of two separate narrowband diode lasers.
Parabolic pulse generation with active or passive dispersion decreasing optical fibers
2007
International audience; We experimentally demonstrate the possibility to generate parabolic pulses via a single dispersion decreasing optical fiber with normal dispersion. We numerically and experimentally investigate the influence of the dispersion profile, and we show that a hybrid configuration combining dispersion decrease and gain has several benefits on the parabolic generated pulses.
Double-pulse single-beam grazing-incidence pumping
2011
The paper reports on the optimization of a table-top nickel-like molybdenum transient collisionally excited soft x-ray laser (SXRL) at 18.9 nm, performed by double-pulse single beam grazing incidence pumping (DGRIP) [1]. This scheme allows for the first time the full control of the pump laser parameters including the pre-pulse duration, optimally generating the SXRL amplifier under grazing incidence. The single beam geometry of collinear double-pulse propagation guarantees the ideal overlap of the pre- and main pulse from shot to shot, resulting in a more efficient, highly stable SXRL output. SXRL energies up to 2.2 µJ are obtained with a total pump energy less than 1 J for several hours at…