Single Particle Emission Research Articles

改进的分裂Bregman方法荧光显微图像复原

荧光显微图像复原有着很多重要的应用，例如，天文成像，电子显微镜成像，单光子发射计算机断层成像术和正电子发射断层成像技术等等。传统基于全变差的分裂Bregman算法能够很好地保护图像边缘和纹理信息，但在图像的平滑区域会产生严重的阶梯效应，针对这一问题，本文提出了一种复原算法，主要考虑两点，一是采用全变差(Total Variation, TV)正则化模型，可以很好地复原模糊图像。二是引入权函数，对TV进行加权抑制阶梯效应，同时保护了图像的纹理信息。通过对参数的合理选择，获得最佳的复原效果，在模拟图像和真实荧光显微图像的实验结果验证了该算法的有效性和可行性。 Fluorescence microscopic image restoration has many very important applications such as astro-nomical imaging, electronic microscopy, single particle emission computed tomography (SPECT) and positron emission tomography (PET). Traditional total variation imaging restoration based on split Bregman algorithm can preserve sharp edges and save the image texture. Serious staircase effect phenomena, however, is generally accompanied. Therefore an improved image restoration algorithm is proposed based on split Bregman in this paper, which is mainly considered two aspects. One is that the total variation regularization model is used, which is an effective tool to recover blurred images. The other is that the weight function of the total variation is involved, which can not only suppress the staircase effect, but also preserve the image texture information. By ap-propriately choosing the reasonable parameters, the better restoration results can be obtained. The experimental results on synthetic images and real fluorescence microscopic images show the effectiveness and feasibility of the proposed algorithm.

Non-blinking (Zn)CuInS/ZnS Quantum Dots Prepared by In Situ Interfacial Alloying Approach.

Semiconductor quantum dots (QDs) are very important optical nanomaterials with a wide range of potential applications. However, blinking behavior of single QD is an intrinsic drawback for some biological and photoelectric applications based on single-particle emission. Herein we present a rational strategy for fabrication of non-blinking (Zn)CuInS/ZnS QDs in organic phase through in situ interfacial alloying approach. This new strategy includes three steps: synthesis of CuInS QDs, eliminating the interior traps of QDs by forming graded (Zn)CuInS alloyed QDs, modifying the surface traps of QDs by introducing ZnS shells onto (Zn)CuInS QDs using alkylthiols as sulfur source and surface ligands. The suppressed blinking mechanism was mainly attributed to modifying QDs traps from interior to exterior via a step-by-step modification. Non-blinking QDs show high quantum yield, symmetric emission spectra and excellent crystallinity, and will enable applications from biology to optoelectronics that were previously hindered by blinking behavior of traditional QDs.

The Initial Single Chiral Particle Emission Mechanism and the Predictions of Charged Charmonium-like Structures

The Initial Single Chiral Particle Emission Mechanism and the Predictions of Charged Charmonium-like Structures

Alternating direction method for the high-order total variation-based Poisson noise removal problem

The restoration of blurred images corrupted by Poisson noise is an important task in various applications such as astronomical imaging, electronic microscopy, single particle emission computed tomography (SPECT) and positron emission tomography (PET). The problem has received significant attention in recent years. Total variation (TV) regularization, one of the standard regularization techniques in image restoration, is well known for recovering sharp edges of an image, but also for producing staircase artifacts. In order to remedy the shortcoming of TV in Poissonian image restoration, we consider a high-order total variation-based optimization model. The optimization model is converted to a constrained problem by variable splitting and then is addressed with the alternating direction method. Numerical results from the Poisson noise removal problem are given to illustrate the validity and efficiency of the proposed method.

Controlling the velocities and the number of emitted particles in the tunneling to open space dynamics

A scheme to control the many-boson tunneling process to open space is derived and demonstrated. The number of ejected particles and their velocities can be controlled by two parameters, the threshold of the potential and the interparticle interaction. Since these parameters are fully under experimental control, this is also the case for the number of ejected particles and their emission spectrum. The process of tunneling to open space can hence be used, for example, for the quantum simulation of complicated tunneling ionization processes and atom lasers. To understand the many-body tunneling process, a generalization of the model introduced in [Proc. Natl. Acad. Sci. USA, 109, 13521 (2012)] for tunneling in the absence of a threshold is put forward and proven to apply for systems with a non-zero threshold value. It is demonstrated that the model is applicable for general interparticle interaction strengths, particle numbers and threshold values. The model constructs the many-body process from single-particle emission processes. The rates and emission momenta of the single-particle processes are determined by the chemical potentials and energy differences to the threshold value of the potential for systems with different particle numbers. The chemical potentials and these energy differences depend on the interparticle interaction. Both the number of confined particles and their rate of emission thus allow for a control by the manipulation of the interparticle interaction and the threshold. Numerically exact results for two, three and one hundred bosons are shown and discussed. The devised control scheme for the many-body tunneling process performs very well for the dynamics of the momentum density, the correlations, the coherence and of the final state, i.e., the number of particles that remain confined in the potential.

The initial single chiral particle emission mechanism and its predictions of charmonium-like structures

We propose a new mechanism, named as the initial single chiral particle emission mechanism, to explain the charged Zb(10610) and Zb(10650) observed in the ϒ(5S) → π+π-ϒ(nS), π+π-hb(mP), (n = 1 ~ 3, m = 1, 2) processes. After successfully interpreting the charge Zb structures, we extend this mechanism to study the process of the dipion transitions between the higher charmonia/charmonium-like state and the lower charmonia. In these transitions process, we predict two charmonium analogs of the charged Zb. After the observations of Zc(3900) by the BESIII and the Belle Collaborations, we reproduce the dipion and the J/ψπ invariant mass distributions simultaneously with the initial single chiral particle emission mechanism. In addition, we predict some enhancements in the J/ψK invariant mass spectra in the dikaon decay of the higher charmonium and the charmonium like states.

Interpreting the Energy-Dependent Anisotropy of Colloidal Nanorods Using Ensemble and Single-Particle Spectroscopy

We report the use of polarized excitation spectroscopy in the study of the polarized optical properties of II–VI semiconducting nanorods. This technique provides a quantitative measure for analyzing the polarization-dependent electronic structure of ensembles of semiconducting nanoparticles in colloidal solutions. We develop a procedure to quantify the anisotropy of nanorod excitations and the influence of the dielectric environment which yields results in qualitative agreement with theoretical predictions of nanorod absorption properties. Excitation measurements of nanorod ensembles and single-particle excitation and emission polarization measurements are used to interpret ensemble measurements on the molecular frame. At the single-particle level, we find a large dispersion in the angles between excitation and emission polarization curves. This contrasts with the conventional picture of CdSe electronic transitions, in which the crystal axes dictate the symmetry of excitations. Such geometrically heteroge...

Predictions of charged charmoniumlike structures with hidden-charm and open-strange channels.

We propose the initial single chiral particle emission mechanism, with which the hidden-charm dikaon decays of higher charmonia and charmoniumlike states are studied. Calculating the distributions of differential decay width, we obtain the line shape of the J/ψK(+) invariant mass spectrum of ψ(i)→J/ψK(+)K(-), where ψ(i)=ψ(4415), Y(4660), and ψ(4790). Our numerical results show that there exist enhancement structures with both hidden-charm and open-strange channels, which are near the D̄(s)(*)/D(*)D̄(s) and D(*)D̄(s)(*)/D̄(*)D(s)(*) thresholds. These charged charmoniumlike structures predicted in this Letter can be accessible in future experiments, especially BESIII, BelleII, and SuperB.

NUCFRG3: Light ion improvements to the nuclear fragmentation model

Light ion improvements to the nuclear fragmentation model, NUCFRG, are reported. Improvements include the replacement of the simple light ion production model with a light ion coalescence model and an improved electromagnetic dissociation (EMD) formalism. Prior versions of the model provide reasonable overall agreement with measured data; however, those versions lack a physics-based description for coalescence and EMD. The version reported herein, NUCFRG3, has improved the theoretical descriptions of these mechanisms and offers additional benefits, such as the capability to calculate EMD cross-sections for single deuteron, triton, helion, and alpha particle emission. NUCFRG3 model evaluation and validation show that the predictive capability has been improved and strengthened by the light ion physics-based changes. Based on increased capability and better theoretical grounding, it is recommended that NUCFRG3 replace its predecessors for space radiation assessments and other applications.

Dipole emitters in fiber: interface effects, collection efficiency and optimization

Single photon emitters coupled to optical fibers are becoming important as sources of non-classical light and nano-scale sensors. At present it is not possible to efficiently interface single photon emitters with the optical fiber platform, and there are particular challenges associated with the need to ensure highly efficient collection and delivery of emitted photons. To model single particle emission, we have considered the coupling of a dipole to an optical fiber mode as a function of orientation and position with respect to the core-cladding interface. Our model shows that it is possible to significantly enhance the collection efficiency into the guided modes as a result of modifications to the dipole emission pattern and power resulting from the surrounding fiber environment. For certain geometries the fiber-dipole coupling can result in a factor of 2.6 increase in the power emitted by the dipole.

Current correlations of an on-demand single-electron emitter

In analogy with quantum optics, short-time correlations of the current fluctuations are measured and used to assess the quality of the single-particle emission of a recently introduced on-demand electron source. We observe, in the context of electronics, the fundamental noise limit associated with the quantum fluctuations of the emission time of single particles, or quantum jittering. In optimum operating conditions of the source, the noise reduces to the quantum jitter limit, which demonstrates single-particle emission. Combined with the coherent manipulations of single electrons in a quantum conductor, this electron quantum optics experiment opens the way to explore new problems including quantum statistics and interactions at the single-electron level.

REAS3: Monte Carlo simulations of radio emission from cosmic ray air showers using an “end-point” formalism

In recent years, the freely available Monte Carlo code REAS for modelling radio emission from cosmic ray air showers has evolved to include the full complexity of air shower physics. However, it turned out that in REAS2 and all other time-domain models which calculate the radio emission by superposing the radiation of the single air shower electrons and positrons, the calculation of the emission contributions was not fully consistent. In this article, we present a revised implementation in REAS3, which incorporates the missing radio emission due to the variation of the number of charged particles during the air shower evolution using an “end-point formalism”. With the inclusion of these emission contributions, the structure of the simulated radio pulses changes from unipolar to bipolar, and the azimuthal emission pattern becomes nearly symmetric. Remaining asymmetries can be explained by radio emission due to the variation of the net charge excess in air showers, which is automatically taken into account in the new implementation. REAS3 constitutes the first self-consistent time-domain implementation based on single particle emission taking the full complexity of air shower physics into account, and is freely available for all interested users.

Deblurring Poissonian images by split Bregman techniques

The restoration of blurred images corrupted by Poisson noise is an important task in various applications such as astronomical imaging, electronic microscopy, single particle emission computed tomography (SPECT) and positron emission tomography (PET). In this paper, we focus on solving this task by minimizing an energy functional consisting of the I-divergence as similarity term and the TV regularization term. Our minimizing algorithm uses alternating split Bregman techniques (alternating direction method of multipliers) which can be reinterpreted as Douglas-Rachford splitting applied to the dual problem. In contrast to recently developed iterative algorithms, our algorithm contains no inner iterations and produces nonnegative images. The high efficiency of our algorithm in comparison to other recently developed algorithms to minimize the same functional is demonstrated by artificial and real-world numerical examples.

Cover Picture: Effect of PCBM Concentration on Photoluminescence Properties of Composite MEH‐PPV/PCBM Nanoparticles Investigated by a Franck–Condon Analysis of Single‐Particle Emission Spectra (ChemPhysChem 14/2009)

The cover picture illustrates the use of composite organic nanoparticles to investigate structure-property relationships of blended functional organic material systems at the molecular and nanoscale. The cartoon in the center shows the type of nanoparticles that were fabricated and studied. In the background, a TEM image of these nanoparticles can be seen in which the dark spots represent the location of individual nanoparticles. Clockwise from the bottom left corner, a photograph of nanoparticle suspensions under UV illumination, a single-particle confocal fluorescence image, single-particle spectral data fitted with a Franck-Condon model, and a cartoon illustrating the concept of using nanoparticles as model systems to study the complex nanostructured active layer in bulk heterojunction organic photovoltaic devices are shown. On page 2449, D. Tenery and A. J. Gesquiere discuss the effects of material morphology and phase separation on exciton delocalization and collapse (trapping) in composite conjugated polymer/fullerene nanoparticles based on a detailed Franck-Condon analysis of single-particle emission spectra.

Quantum Barrier Penetration Studies with Oriented Nuclei: Proton and Neutron Emission from Exotic Isotopes

We report a programme of novel experiments involving direct proton emission and β-delayed proton and neutron emission for exotic nuclei oriented at low temperatures. Full modelling of the quantum tunneling and angular distribution has been made for the first time for these processes. Their study has application in many fields of natural science. The study of barrier effects involving angular momentum and non-spherical deformation can be approached more directly via single-particle emission than via alpha decay, which suffers from complications relating to preformation of the alpha particle. Using the new formalism, predictions are presented for angular distributions of β-delayed neutrons from oriented 137I and of direct proton emission from oriented 147Tm.

On the Secondary Photoemission Through the Double Layer

Splitting the double layer into autonomous cells is essential during the photoemission from a metal into a solution. An emitted electron participates in the discharge of the double cell isolated from the other part of the interface. The work function of such an electron decreases by a value which is half of the quantity accepted for a single-particle emission. Comparing the new value with the experimental data shows that the interfacial photocurrent is produced by the secondary electrons which acquire the energy in collisions with the primary ones.

Characterizing submicron vesicles with wavelength-resolved fluorescence in flow cytometry

Individual synthetic vesicles 0.1-1.0 micron in diameter are sized by using single-particle fluorescence emission spectra obtained in a custom sheath flow cell with an imaging spectrograph and a charge-coupled device. Data are acquired at 1 Hz, with limits of detection (3 sigma) less than 6.0 x 10(3) and 1.0 x 10(4) molecules of free sulforhodamine 101 and fluorescein, respectively, and with a spectral range for fluorescence emission collection from 350 to 800 nm (0.45 nm/pixel resolution). The system is used for small-particle population analysis by analyzing a suspension of submicron, unilamellar, synthetic vesicles prepared by standard procedures with phosphatidylserine and Texas red- or fluorescein head-group-conjugated dihydropalmitoylphosphatidylethanolamine. The submicron particles are individually identified, sized, and discriminated based on single-particle fluorescence emission spectra. Excellent agreement is found between fluorescence sizing data and transmission electron microscopic measurements.

Improved Temperature Measurements of Burning Char and Coal Particles Using an FT-IR Spectrometer

A novel method for temperature measurements on individual burning char and coal particles with an FT-IR spectrometer has been developed. The technique is demonstrated for monitoring emission spectra of individual moving particles that require a few milliseconds to pass the field of view of a conventional scanning FT-IR spectrometer. The accurate particle surface temperature is calculated from a best match of the measured emission spectrum to a detailed physical radiance model spectrum. The technique is applied to measure the surface temperature of 90−125 μm particles with temperatures from 1000 to 2200 K in an entrained flow reactor. A one-temperature calibration of the FT-IR spectrometer is sufficient for accurate measurements throughout a broad temperature range. Background radiation and a fluctuating particle feeding rate are handled by subtraction of two successive measurements. The single-particle emission spectra are useful for testing the assumptions about particle emissivity as a function of wavel...

Cross-section measurements for 7Li + 11B AND 7Li + 13C reactions at low energies

The 7Li + 11B and 7Li + 13C reactions have been studied at incident energies below and around the Coulomb barrier, by measurement of the cross sections for the characteristic γ-rays emitted by the residual nuclei. The nα, αα and np emission channels are found to be enhanced with respect to the statistical compound nucleus predictions, while the nn and single-particle emission channels are not enhanced. An unusual energy dependence is observed for the 7 Li + 11 B → nn 16O 7.12 MeV channel cross section, suggesting the existence of a broad resonance.

Deexcitation gamma rays following the photodisintegration of 17O.

Bremsstrahlung-weighted integrated cross sections for photoproton and photoneutron emission from $^{17}\mathrm{O}$ to excited residual states in $^{16}\mathrm{N}$ and $^{16}\mathrm{O}$ have been measured by detecting the deexcitation \ensuremath{\gamma} rays emitted from these states in the residual nuclei. The results are compared with the previously reported $^{17}(\ensuremath{\gamma}$,p) and $^{17}(\ensuremath{\gamma}$,n) cross sections. About 90% of photoproton emission from $^{17}\mathrm{O}$ populates the ground-state ${(2}^{\mathrm{\ensuremath{-}}}$) and the 0.298-MeV ${(3}^{\mathrm{\ensuremath{-}}}$) level in $^{16}\mathrm{N}$. It is concluded that this is the result of a single-particle excitation and emission process. The remaining photoproton emission, leading to the 0.120-MeV ${(0}^{\mathrm{\ensuremath{-}}}$) and 0.397-MeV ${(1}^{\mathrm{\ensuremath{-}}}$) levels, occurs during the preequilibrium stage or from the compound nucleus. The results further indicate that these decay fractions are approximately independent of excitation energy in $^{17}\mathrm{O}$. For the $^{17}(\ensuremath{\gamma}$,n${)}^{16}$O reaction, the results show that emission to bound states in $^{16}\mathrm{O}$ is predominantly to the $^{16}\mathrm{O}$ ground state ${(0}^{+}$), with 4% of the decay from the $^{17}\mathrm{O}$ giant dipole resonance going to the 6.13-MeV ${(3}^{\mathrm{\ensuremath{-}}}$) excited state; population of other bound states is not observed.