Tectonism and volcanism forced by glaciation and deglaciation events in southern Iceland

International audienc

Tectonism and volcanism forced by glaciation and deglaciation events in southern Iceland

International audienc

Tectonism and volcanism forced by glaciation and deglaciation events in southern Iceland

International audienc

Highly Luminescent Dinuclear Platinum(II) Complexes Incorporating Bis-Cyclometallating Pyrazine-Based Ligands: A Versatile Approach to Efficient Red Phosphors

A series of luminescent dinuclear platinum(II) complexes incorporating diphenylpyrazine-based bridging ligands ((LH2)-H-n) has been prepared. Both 2,5-diphenylpyrazine ((LH2)-H-2) and 2,3-diphenylpyrazine ((LH2)-H-3) are able to undergo cyclometalation of the two phenyl rings, with each metal ion binding to the two nitrogen atoms of the central heterocycle, giving, after treatment with the anion of dipivaloyl methane (dpm), complexes of formula \{Pt(dpm)\}(2)L-n. These compounds are isomers of the analogous complex of 4,6-diphenylpyrimidine ((LH2)-H-1). Related complexes of dibenzo-(f,h)quinoxaline ((LH2)-H-4), 2,3-diphenyl-quinoxaline ((LH2)-H-5), and dibenzo{[}3,2-a:2',3'-c]phenazine ((LH2)-H-6) have also been prepared, allowing the effects of strapping together the phenyl rings ((LH2)-H-4 and (LH2)-H-6) and/or extension of the conjugation from pyrazine to quinoxaline ((LH2)-H-5 and (LH2)-H-6) to be investigated. In all cases, the corresponding mononuclear complexes, Pt(dpm)(LH)-H-n, have been isolated too. All 12 complexes are phosphorescent in solution at ambient temperature. Emission spectra of the dinuclear complexes are consistently red shifted compared to their mononuclear analogues, as are the lowest energy absorption bands. Electrochemical data and TD-DFT calculations suggest that this effect arises primarily from stabilization of the LUMO. Introduction of the second metal ion also has the effect of substantially increasing the molar absorptivity and, in most cases, the radiative rate constants. Meanwhile, extension of conjugation in the heterocycle of (LH2)-H-5 and (LH2)-H-6 and planarization of the aromatic system favored by interannular bond formation in (LH2)-H-4 and (LH2)-H-6 leads to further red shifts of the absorption and emission spectra to wavelengths that are unusually long for cyclometalated platinum(II) complexes. The results may offer a versatile design strategy for tuning and optimizing the optical properties of d-block metal complexes for contemporary applications

SAMPA chip: a new ASIC for the ALICE TPC and MCH upgrades

This paper presents the SAMPA, an ASIC designed for the upgrade of read-out front end electronics of the ALICE Time Projection Chamber (TPC) and Muon Chambers (MCH). SAMPA is made in a 130 nm CMOS technology with 1.25 V nominal voltage supply and includes 32 channels, with selectable input polarity, and five possible combinations of shaping time and sensitivity. Each channel comprises a Charge Sensitive Amplifier, a semi-Gaussian shaper and a 10-bit ADC, followed by a Digital Signal Processor. A prototype in a multi project run was submitted to evaluate the performance of each of these blocks. The experimental results of the tests on these building blocks are presented, showing a substantial agreement with requirements