Tuning the contact conductance of anchoring groups in single molecule junctions by molecular design

A tetraphenylmethane tripod functionalized with three thiol moieties in the para position can serve as a supporting platform for functional molecular electronic elements. A combined experimental scanning tunneling microscopy break junction technique with theoretical approaches based on density functional theory and non-equilibrium Green`s function formalism was used for detailed charge transport analysis to find configurations, geometries and charge transport pathways in the molecular junctions of single molecule oligo-

Fine tuning of the catalytic effect of a metal-free porphyrin on the homogeneous oxygen reduction

The catalytic effect of tetraphenylporphyrin on the oxygen reduction with ferrocene in 1,2-dichloroethane can be finely tuned by varying the molar ratio of the acid to the catalyst present in the solution. The mechanism involves binding of molecular oxygen to the protonated free porphyrin base, in competition with ion pairing between the protonated base and the acid anion present

Proceedings of the 12th International Conference on Kinanthropology

Proceedings of the 12th Conference of Sport and Quality of Life 2019 gatheres submissions of participants of the conference. Every submission is the result of positive evaluation by reviewers from the corresponding field. Conference is divided into sections – Analysis of human movement; Sport training, nutrition and regeneration; Sport and social sciences; Active ageing and sarcopenia; Strength and conditioning training; section for PhD students

GNSS Profile from the Greenland Korth Expeditions in the Context of Satellite Data

Over the last two decades, a small group of researchers repeatedly crossed the Greenland interior skiing along a 700-km long route from east to west, acquiring precise GNSS measurements at exactly the same locations. Four such elevation profiles of the ice sheet measured in 2002, 2006, 2010 and 2015 were differenced and used to analyze the surface elevation change. Our goal is to compare such locally measured GNSS data with independent satellite observations. First, we show an agreement in the rate of elevation change between the GNSS data and satellite radar altimetry (ERS, Envisat, CryoSat-2). Both datasets agree well (2002–2015), and both correctly display local features such as an elevation increase in the central part of the ice sheet and a sharp gradual decline in the surface heights above Jakobshavn Glacier. Second, we processed satellite gravimetry data (GRACE) in order for them to be comparable with local GNSS measurements. The agreement is demonstrated by a time series at one of the measurement sites. Finally, we provide our own satellite gravimetry (GRACE, GRACE-FO, Swarm) estimate of the Greenland mass balance: first a mild decrease (2002–2007: −210 ± 29 Gt/yr), then an accelerated mass loss (2007–2012: −335 ± 29 Gt/yr), which was noticeably reduced afterwards (2012–2017: −178 ± 72 Gt/yr), and nowadays it seems to increase again (2018–2019: −278 ± 67 Gt/yr)

Femtosecond Fluorescence and Intersystem Crossing in Rhenium(I) Carbonyl-Bipyridine Complexes

Ultrafast electronic-vibrational relaxation upon excitation of the singlet charge-transfer b1A' state of [Re(L)(CO)3(bpy)]n (L = Cl, Br, I, n = 0; L = 4-Et-pyridine, n = 1+) in acetonitrile was investigated using the femtosecond fluorescence up-conversion technique with polychromatic detection. In addn., energies, characters, and mol. structures of the emitting states were calcd. by TD-DFT. The luminescence is characterized by a broad fluorescence band at very short times, and evolves to the steady-state phosphorescence spectrum from the a3A" state at longer times. The anal. of the data allows us to identify three spectral components. The first two are characterized by decay times t1 = 85-150 fs and t2 = 340-1200 fs, depending on L, and are identified as fluorescence from the initially excited singlet state and phosphorescence from a higher triplet state (b3A"), resp. The third component corresponds to the long-lived phosphorescence from the lowest a3A" state. In addn., it is found that the fluorescence decay time (t1) corresponds to the intersystem crossing (ISC) time to the two emissive triplet states. t2 corresponds to internal conversion among triplet states. DFT results show that ISC involves electron exchange in orthogonal, largely Re-localized, MOs, whereby the total electron momentum is conserved. Surprisingly, the measured ISC rates scale inversely with the spin-orbit coupling const. of the ligand L, but the authors find a clear correlation between the ISC times and the vibrational periods of the Re-L mode, suggesting that the latter may mediate the ISC in a strongly nonadiabatic regime

The growth of zinc phthalocyanine thin films by pulsed laser deposition

International audienceZinc phthalocyanine (ZnPc) thin films were prepared by pulsed laser deposition (PLD) using KrF laser (λ = 248 nm, τ = 5 ns). The effect of laser fluence (in the region from 10 to 100 mJ/cm2) and repetition rate of 50 and 200 Hz to the film growth and its properties was investigated. The growth of ZnPc thin film was in situ monitored using transmission measurement in ultraviolet-visible spectral range. The optical properties in conjunction with density functional theory/time-dependent density functional theory calculations suggested the growth of the film in β-phase. X-ray diffraction also revealed crystalline character of the film. The electrical properties analyzed by van der Pauw method exhibited resistivity ρ ≈ 108–1010 Ω cm. Fourier transform infrared spectroscopy analyses revealed low deterioration of PLD deposited ZnPc films. We demonstrate that, by finely tuning the deposition conditions, PLD is a successful technique for fabrication of ZnPc thin films

Direct detection of the mercury-nitrogen bond in the thymine-Hg-II-thymine base-pair with Hg-199 NMR spectroscopy

One-bond 199Hg–15N J-coupling.</p