Search results for "citation"

Transition-Selective Pulses in Zero-Field Nuclear Magnetic Resonance.

2016

We use low-amplitude, ultralow frequency pulses to drive nuclear spin transitions in zero and ultralow magnetic fields. In analogy to high-field NMR, a range of sophisticated experiments becomes available as these allow narrow-band excitation. As a first demonstration, pulses with excitation bandwidths 0.5–5 Hz are used for population redistribution, selective excitation, and coherence filtration. These methods are helpful when interpreting zero- and ultralow-field NMR spectra that contain a large number of transitions.

2016

The photochemistry of benzophenone, a paradigmatic organic molecule for photosensitization, was investigated by means of surface-hopping ab initio molecular dynamics. Different mechanisms were found to be relevant within the first 600 fs after excitation; the long-debated direct (S1 → T1) and indirect (S1 → T2 → T1) mechanisms for population of the low-lying triplet state are both possible, with the latter being prevalent. Moreover, we established the existence of a kinetic equilibrium between the two triplet states, never observed before. This fact implies that a significant fraction of the overall population resides in T2, eventually allowing one to revisit the usual spectroscopic assignm…

Origin of the large spectral shift in electroluminescence in a blue light emitting cationic iridium(III) complex

2007

A new, but archetypal compound [ Ir( ppy- F-2) (2)Me(4)phen] PF6, where ppy- F2 is 2-(2',4'- fluorophenyl) pyridine and Me(4)phen is 3,4,7,8- tetramethyl- 1,10- phenanthroline, was synthesized and used to prepare a solid-state light-emitting electrochemical cell (LEEC). This complex emits blue light with a maximum at 476 nm when photoexcited in a thin film, with a photoluminescence quantum yield of 52%. It yields an efficient single-component solid-state electroluminescence device with a current efficiency reaching 5.5 cd A(-1) and a maximum power efficiency of 5.8 Lm Watt(-1). However, the electroluminescence spectrum is shifted with respect to the photoluminescence spectrum by 80 nm resul…

Coauthorship networks and institutional collaboration patterns in reproductive biology.

2007

Objective Reproductive biology is a highly productive area. By analyzing papers published in the major journals in the period 2003–2005, the collaborative patterns were characterized. Design Original research papers published in 2004 in the journals included in the first quartile of the category "Reproductive Biology" of the Journal Citation Reports (2005) were selected. A bibliometric analysis was carried out with the information obtained, thus building up the networks of coauthorship and institutional collaboration. Result(s) A total of 4,702 papers were analyzed, 96.75% signed in collaboration by two or more authors, the authors per paper index being 5.24; 73.73% of the papers were colla…

Active photonic crystals based on surface acoustic waves

2003

An active photonic crystal (PC) based on the modulation of a one-dimensional cavity resonator by electrically-generated surface acoustic waves is described. The high nonthermal population of surface modes combined with the enhanced Brillouin scattering in the cavity increases the intensity of the scattered light to values comparable to the excitation intensity. This process is employed to switch and modulate light beams in PCs.

Two‐Dimensional Electron Gas Effects on the Photoluminescence from a Nonintentionally Doped AlGaN/GaN Heterojunction

2002

Photoluminescence measurements on an AlGaN/GaN single heterojunction (SH), where piezoelectric and spontaneous polarization effects confine a two-dimensional electron gas (2DEG), are presented. Well-defined emissions between the bulk excitonic transitions and their LO-phonon replica are attributed to spatially indirect excitons located close to the interface. The strong interfacial electric field separates photogenerated holes and electrons, weakening their Coulomb interaction and causing a blueshift with increasing excitation intensity due to carrier population effects. In addition, direct experimental proof is obtained by applying an electric field normal to the interface. An energy shift…

Two-photon excitation microscopy of tryptophan-containing proteins.

2002

We have examined the feasibility of observing single protein molecules by means of their intrinsic tryptophan emission after two-photon excitation. A respiratory protein from spiders, the 24-meric hemocyanin, containing 148 tryptophans, was studied in its native state under almost in vivo conditions. In this specific case, the intensity of the tryptophan emission signals the oxygen load, allowing one to investigate molecular cooperativity. As a system with even higher tryptophan content, we also investigated latex spheres covered with the protein avidin, resulting in 340 tryptophans per sphere. The ratio of the fluorescence quantum efficiency to the bleaching efficiency was found to vary b…

Photodynamics of a Molecular Water-Soluble Nanocluster Identified as Au130(pMBA)50

2015

Photodynamics of a highly monodisperse sample of a water-soluble gold nanocluster tentatively identified as Au130(pMBA)50 (pMBA = p-mercaptobenzoic acid) was studied by mid-IR transient absorption spectroscopy with visible excitation. The observed long-lived excited states (>1 ns) indicate a molecular behavior of the cluster. By combining the transient absorption data with DFT calculation results the observed relaxation dynamics could be fully explained by identifying several relaxation processes involving singlet and triplet manifolds. The results indicate that the cluster may have interesting transient magnetic properties due to a long-lived triplet population.

Structure of superheavy nuclei along decay chains of element 115

2014

[Introduction] A recent high-resolution α , X -ray, and γ -ray coincidence-spectroscopy experiment offered the first glimpse of excitation schemes of isotopes along α -decay chains of Z = 115. To understand these observations and to make predictions about shell structure of superheavy nuclei below 288 115, we employ two complementary mean-field models: the self-consistent Skyrme energy density functional approach and the macroscopic-microscopic Nilsson model. We discuss the spectroscopic information carried by the new data. In particular, candidates for the experimentally observed E 1 transitions in 276 Mt are proposed. We find that the presence and nature of low-energy E 1 transitions in w…

Enhancing Older Adults’ Digital Inclusion Through Social Support : A Qualitative Interview Study

2022

AbstractA lack of social support can hinder older adults’ digital inclusion. This chapter examines the connection between social and digital inclusion by focusing on the process of acquiring social support for digital technology use among older adults in Finland. Building on the concept of warm expert, the chapter shows that acquiring support for digital technology use is a reciprocal process that both enhances and requires digital inclusion. A qualitative analysis of 22 participant-induced elicitation interviews was conducted with older adults aged between 57 and 89. The chapter shows that social support reinforces digital inclusion by (a) ensuring older adults’ access to technology, (b) c…