Introduction of an isopropyl bridge in the triangulenium skeleton leads to a new series of redshifted triangulenium dyes with high fluorescence quantum yields and remarkable long fluorescence lifetime allowing for time-gated cell imaging.
The spectral properties of emissive photoproducts, formed upon 633 nm irradiation of a terrylene diimide dye, were investigated. Ensemble and single-molecule level experiments were conducted by immobilizing the TDI dye molecules in a polystyrene film. In the bulk experiments, green emission could be observed from the photobleached areas (photobleached with 633 nm light) when excited with 480 or 514 nm light. Similar phenomena were also observed at the single-molecule level. On the basis of the single-molecule experiments, a conversion efficiency of about 5% was estimated for the formation of emissive spectrally blue-shifted photoproducts. These green emissive photoproducts have spectral properties that resemble those of lower rylene homologues, e.g. perylene diimide or perylene monoimide. Our results indicate that the formation of blue-shifted emissive photoproducts can have implications for analyzing single-molecule FRET experiments or multiple color-labeled fluorescent systems.
The discovery of nonmagnetic Weyl semimetals (WSMs) in TaAs compounds has triggered lots of efforts in finding its magnetic counterpart. While the direct observation of the Weyl nodes and Fermi arcs in a magnetic candidate through angle-resolved photoemission spectroscopy is hindered by the complex magnetic domains. The transport features of magnetic WSMs, including negative magnetoresistivity and anomalous Hall conductivity, are not conclusive since these are sensitive to extrinsic factors like defects and disorders in lattice or magnetic ordering. Here, we systematically study the temperature dependent optical spectra of ferromagnetic Co3Sn2S2 experimentally and simulated by first-principles calculations. The many-body correlation effect due to Co 3d electrons leads to renormalization of bands by a factor about 1.33, which is moderate and the description within density functional theory is suitable. As temperature drops down, the magnetic phase transition happens and the magnetization drives the band shift through exchange splitting. The optical spectra can well detect these changes, including the transitions sensitive and insensitive to the magnetization, and those from the bands around the Weyl nodes. The results strongly support that Co3Sn2S2 is a magnetic WSM and the Weyl nodes can be tuned by magnetization with temperature change.PACS numbers: 72.15.-v, 74.70.-b, 78.30.-j Recently, the shandite compound Co 3 Sn 2 S 2 has attracted lots of attentions since it not only shows intrinsic ferromagnetism but also is proposed to have three pairs of Weyl points around the Fermi level in the first Brillouin zone (BZ) [1-3, 5]. For its quasi-two-dimensional crystal structure, low carrier density and strong anomalous Hall effect (AHE), Co 3 Sn 2 S 2 has been thought as a potential candidate to realize the quantum AHE [6,7] in its tow-dimensional (2D) limit [1,8,9]. As a candidate of magnetic Weyl semimetal (WSM) [10], the magnetic ordering states are expected to have interactions with Weyl nodes [2,3], so that the topological properties from WSM can be finely tuned through control of magnetization [2,11]. Actually, it has been found that upon cooling, the magnetization and anomalous Hall conductivity (AHC) of Co 3 Sn 2 S 2 vary accordingly [1, 2] and the first-principles calculations of AHC at different magnetization has shown their intrinsic relationship through the changes in the position of Weyl nodes [2]. To check whether this picture is true or not in realistic samples, here we have performed systematical optical spectra measurements under different temperatures (T s). The advantages of optical spectra measurements over the AHC measurements are as following: First, optical spectrum is * These authors contributed equally to this work. † hmweng@iphy.ac.cn ‡ xgqiu@iphy.ac.cn
The narrow, near infrared (NIR) emission from lanthanide ions has attracted great interest, particularly with regard to developing tools for bioimaging, where the long lifetimes of lanthanide excited states can be exploited to address problems arising from autofluorescence and sample transparency. Despite the promise of lanthanide-based probes for near-IR imaging, few reports on their use are present in the literature. Here, we demonstrate that images can be recorded by monitoring NIR emission from lanthanide complexes using detectors, optical elements and a microscope that were primarily designed for the visible part of the spectrum.
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