scholarly journals Chiroptical spectroscopy of a freely diffusing single nanoparticle

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Johannes Sachs ◽  
Jan-Philipp Günther ◽  
Andrew G. Mark ◽  
Peer Fischer
Keyword(s):  
Spectroscopic Observation ◽  
Molecular Response ◽  
Single Particles ◽  
Time Resolved ◽  
Single Nanoparticle ◽  
Spectral Interpretation ◽  
Fixed Orientation ◽  
Freely Moving ◽  
Single Particle Spectroscopy ◽  
Chiroptical Spectroscopy

Abstract Chiral plasmonic nanoparticles can exhibit strong chiroptical signals compared to the corresponding molecular response. Observations are, however, generally restricted to measurements on stationary single particles with a fixed orientation, which complicates the spectral analysis. Here, we report the spectroscopic observation of a freely diffusing single chiral nanoparticle in solution. By acquiring time-resolved circular differential scattering signals we show that the spectral interpretation is significantly simplified. We experimentally demonstrate the equivalence between time-averaged chiral spectra observed for an individual nanostructure and the corresponding ensemble spectra, and thereby demonstrate the ergodic principle for chiroptical spectroscopy. We also show how it is possible for an achiral particle to yield an instantaneous chiroptical response, whereas the time-averaged signals are an unequivocal measure of chirality. Time-resolved chiroptical spectroscopy on a freely moving chiral nanoparticle advances the field of single-particle spectroscopy, and is a means to obtain the true signature of the nanoparticle’s chirality.

Time-Resolved Spectroscopic Observation of Diphenylnitrenium Ion Reactions with Guanosine

2020 ◽  
Vol 85 (14) ◽  
pp. 8792-8797
Author(s):  
Lili Du ◽  
Zhiping Yan ◽  
Zhiyuan Zhu ◽  
Shun-Cheung Cheng ◽  
Yue Zhang ◽  
...  
Keyword(s):  
Spectroscopic Observation ◽  
Time Resolved

Luminescence Intermittency and Quantum Efficiency of Individual Porous Si Nanoparticles.

1999 ◽  
Vol 560 ◽  
Author(s):  
Michael D. Mason ◽  
Grace M. Credo ◽  
Paul J. Carson ◽  
Steven K. Buratto
Keyword(s):  
Quantum Efficiency ◽  
Colloidal Suspension ◽  
Porous Si ◽  
Time Resolved ◽  
High Quantum Efficiency ◽  
Si Nanoparticles ◽  
Shear Force Microscopy ◽  
Spectrally Resolved ◽  
Single Particle Spectroscopy ◽  
Microscopy Techniques

ABSTRACTWe have recently observed spectrally resolved vibronic structure and luminescence intermittency from nanometer-size porous silicon nanocrystals. In this study we examine the quantum efficiency of a single nanoparticle and show that emitting nanoparticles do so with near unity quantum efficiency. This result suggests that the emission from porous Si nanoparticles, and thus bulk porous Si, results from a small number of high quantum efficiency emitters. In our previous work we have shown that our nanoparticles contain more than one coupled chromophore. In order to examine these effects more closely we employ several spectroscopy and microscopy techniques including: 1) single-particle spectroscopy, 2) shear-force microscopy, and 3) time-resolved spectroscopy, on a colloidal suspension of size-selected, surface-oxidized nanoparticles. In addition we apply statistical techniques to provide a more complete picture of the coupling between chromophores in a given nanoparticle.

scholarly journals Coherent convergent-beam time-resolved X-ray diffraction

2014 ◽  
Vol 369 (1647) ◽  
pp. 20130325 ◽  
Author(s):  
John C. H. Spence ◽  
Nadia A. Zatsepin ◽  
Chufeng Li
Keyword(s):  
Single Shot ◽  
Beam Diameter ◽  
X Ray Diffraction ◽  
Single Particles ◽  
Time Resolved ◽  
X Ray ◽  
Challenges And Opportunities ◽  
Phase Sensitive ◽  
Diffraction Patterns ◽  
Convergent Beam

The use of coherent X-ray lasers for structural biology allows the use of nanometre diameter X-ray beams with large beam divergence. Their application to the structure analysis of protein nanocrystals and single particles raises new challenges and opportunities. We discuss the form of these coherent convergent-beam (CCB) hard X-ray diffraction patterns and their potential use for time-resolved crystallography, normally achieved by Laue (polychromatic) diffraction, for which the monochromatic laser radiation of a free-electron X-ray laser is unsuitable. We discuss the possibility of obtaining single-shot, angle-integrated rocking curves from CCB patterns, and the dependence of the resulting patterns on the focused beam coordinate when the beam diameter is larger or smaller than a nanocrystal, or smaller than one unit cell. We show how structure factor phase information is provided at overlapping interfering orders and how a common phase origin between different shots may be obtained. Their use in refinement of the phase-sensitive intensity between overlapping orders is suggested.

Joining Time-Resolved Thermometry and Magnetic-Induced Heating in a Single Nanoparticle Unveils Intriguing Thermal Properties

ACS Nano ◽  
2015 ◽  
Vol 9 (3) ◽  
pp. 3134-3142 ◽  
Author(s):  
Rafael Piñol ◽  
Carlos D. S. Brites ◽  
Rodney Bustamante ◽  
Abelardo Martínez ◽  
Nuno J. O. Silva ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Time Resolved ◽  
Single Nanoparticle

Direct Time-Resolved Spectroscopic Observation of Arylnitrenium Ion Reactions with Guanine-Containing DNA Oligomers

2014 ◽  
Vol 79 (8) ◽  
pp. 3610-3614 ◽  
Author(s):  
Jiadan Xue ◽  
Lili Du ◽  
Ruixue Zhu ◽  
Jinqing Huang ◽  
David Lee Phillips
Keyword(s):  
Spectroscopic Observation ◽  
Dna Oligomers ◽  
Time Resolved

Time-resolved ESR study on photochemical formation of radical pair in cyclodextrin cavities

1991 ◽  
Vol 69 (11) ◽  
pp. 1643-1648 ◽  
Author(s):  
Hisao Murai ◽  
Yoshinori Yamamoto ◽  
Yasumasa J. I'Haya
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Spin Polarization ◽  
Room Temperature ◽  
Radical Pair ◽  
Ion Pair ◽  
Time Resolved ◽  
Excited Triplet ◽  
Photochemical Formation ◽  
Fixed Orientation

The photoreduction of xanthone with diethylaniline in cyclodextrin cavities was studied at 77 K and room temperature by a time-resolved ESR technique. The radical pair observed in β- and γ-cyclodextrins showed inverted spin polarization compared to that of precursor excited triplet xanthone. This result is rationalized by taking account of the fixed orientation of the radical ion pair in the cyclodextrins. Frozen aqueous solutions and dried powder-like samples provided similar results. The spectrum of the radical pair was also detected in an aqueous solution of β-cyclodextrin at room temperature. Key words: cyclodextrins, xanthone, spin polarization, radical ion-pair, time-resolved ESR.

scholarly journals Serial Femtosecond Crystallography user's consortium apparatus at European XFEL

2014 ◽  
Vol 70 (a1) ◽  
pp. C1748-C1748
Author(s):  
Marc Messerschmidt ◽  
Leonard Chavas ◽  
Sunil Ananthaneni ◽  
Hamidreza Dadgostar ◽  
Heinz Graafsma ◽  
...  
Keyword(s):  
Protein Crystal ◽  
Pixel Detector ◽  
Single Particles ◽  
Time Resolved ◽  
X Ray ◽  
Overall Design ◽  
Laser Facility ◽  
Common Problems ◽  
Automated Procedures ◽  
Serial Femtosecond Crystallography

The Serial Femtosecond Crystallography (SFX) user's consortium apparatus is to be installed within the Single Particles, Clusters and Biomolecules (SPB) instrument of the European X-ray Free-Electron Laser facility (XFEL.EU) [1, 2]. The XFEL.EU will provide ultra-short, highly intense, coherent X-ray pulses at an unprecedented repetition rate. The experimental setup and methodological approaches of many scientific areas will be transformed, including structural biology that could potentially overcome common problems and bottlenecks encountered in crystallography, such as creating large crystals, dealing with radiation damage, or understanding sub-picosecond time-resolved phenomena. The key concept of the SFX method is based on the kinetic insertion of protein crystal samples in solution via a gas dynamic virtual nozzle jet and recording diffraction signals of individual, randomly oriented crystals passing through the XFEL beam, as first demonstrated by Chapman et al. [3]. The SFX-apparatus will refocus the beam spent by the SPB instrument into a second interaction region, in some cases enabling two parallel experiments. The planned photon energy range at the SPB instrument is from 3 to 16 keV. The Adaptive Gain Integrating Pixel Detector (AGIPD) is to be implemented in the SPB instrument, including a 4 Megapixel version for the SFX-apparatus. The AGIPD is designed to store over 350 data frames from successive pulses, and aims to collect more than 3,000 images per second. Together with the implementation of automated procedures for sample exchange and injection, high-throughput nanocrystallography experiments can be integrated at the SFX-apparatus. In this work, we review the overall design of the SFX-apparatus and discuss the main parameters and challenges

scholarly journals A time-resolved proteomic and diagnostic map characterizes COVID-19 disease progression and predicts outcome

2020 ◽  
Author(s):  
Vadim Demichev ◽  
Pinkus Tober-Lau ◽  
Tatiana Nazarenko ◽  
Charlotte Thibeault ◽  
Harry Whitwell ◽  
...  
Keyword(s):  
Disease Progression ◽  
Host Response ◽  
Clinical Decision Making ◽  
Treatment Strategies ◽  
Clinical Decision ◽  
Organ Damage ◽  
Supplemental Oxygen ◽  
Asymptomatic Infection ◽  
Molecular Response ◽  
Time Resolved

AbstractCOVID-19 is highly variable in its clinical presentation, ranging from asymptomatic infection to severe organ damage and death. There is an urgent need for predictive markers that can guide clinical decision-making, inform about the effect of experimental therapies, and point to novel therapeutic targets. Here, we characterize the time-dependent progression of COVID-19 through different stages of the disease, by measuring 86 accredited diagnostic parameters and plasma proteomes at 687 sampling points, in a cohort of 139 patients during hospitalization. We report that the time-resolved patient molecular phenotypes reflect an initial spike in the systemic inflammatory response, which is gradually alleviated and followed by a protein signature indicative of tissue repair, metabolic reconstitution and immunomodulation. Further, we show that the early host response is predictive for the disease trajectory and gives rise to proteomic and diagnostic marker signatures that classify the need for supplemental oxygen therapy and mechanical ventilation, and that predict the time to recovery of mildly ill patients. In severely ill patients, the molecular phenotype of the early host response predicts survival, in two independent cohorts and weeks before outcome. We also identify age-specific molecular response to COVID-19, which involves increased inflammation and lipoprotein dysregulation in older patients. Our study provides a deep and time resolved molecular characterization of COVID-19 disease progression, and reports biomarkers for risk-adapted treatment strategies and molecular disease monitoring. Our study demonstrates accurate prognosis of COVID-19 outcome from proteomic signatures recorded weeks earlier.

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