Photon Emission Intensity Research Articles

Emission dynamics of optically driven aluminum nitride quantum emitters

Aluminum nitride is a technologically important wide band-gap semiconductor which has been shown to host bright quantum emitters. We use photon emission correlation spectroscopy (PECS), time-resolved photoluminescence (TRPL), and state-population dynamic simulations to probe the dynamics of emission under continuous wave (CW) and pulsed optical excitation. We infer that there are at least four dark shelving states, which govern the TRPL, bunching, and saturation of the optical transition. We study in detail the emission dynamics of two quantum emitters (QEs) with differing power-dependent shelving processes, hypothesized to result from charge ionization and recombination. These results demonstrate that photon bunching caused by shelving the system in a dark state inherently limits the saturation rate of the photon source. In emitters where increasing optical power deshelves the dark states, we observe an increased photon emission intensity. Published by the American Physical Society 2024

Biophoton emission-based approach of the effects of systemic insecticides on the survival of Eurydema ventralis Kolenati, 1846 (Hemiptera: Pentatomidae) and on the photosynthetic activity of oilseed rape

The choice of effective crop protection technologies is a key factors in the economical production of oilseed rape. Insecticides belonging to the group of active substances butenolides and diamides are active substances available as seed treatments in oilseed rape and promising control tools in the crop protection technologies. Our laboratory experiment demonstrated that the experimental insecticides flupyradifurone and cyantraniliprole are both effective against Eurydema ventralis (Hemiptera: Pentatomidae) when used as a seed and in-crop treatments, but there is a fundamental difference in their insect mortality inducing effects. Flupyradifurone was found to have a total mortality 96 h after application based on basipetal translocation. In the case of cyantraniliprole, the insecticidal effect of the same treatment was 27% less. The experiment showed that the acropetal translocation of the tested active substances after seed treatment did not induce efficacy comparable to that of the basipetal translocation. The study of the biophoton emission of the plants demonstrated a verifiable correlation between the different application methods of the insecticides and the photon emission intensity per unit plant surface area. In conclusion, the systematic insecticides tested, in addition to having the expected insecticidal effect, interfere with plant life processes by enhancing photosynthetic activity.

Optimization of the Modes of Pre-Sowing Electrical Stimulation of Winter Rape Seeds Based on the Study of the Intensity of Single Photon Emission by Them

Abstract The article presents the results that can be a prerequisite for the introduction of a pre-sowing electrotreatment of winter rape seeds into the production process. The results of photon emission by rape seeds after electrical stimulation are highly correlated with the data obtained during determination of its sowing qualities and field germination. Absorption and transformation of the energy of the external electric field during the electrostimulation of winter rape seeds occurs non-linearly. It was established that the main transformations take place during the first 15 s, regardless of the electric field intensity. Relaxation processes were revealed, which become dominant after 15 s of electrical stimulation. The pre-sowing electrical stimulation improved the sowing properties of winter rapeseed. The highest values of germination energy and laboratory germination (87% and 96%), which exceeded the control by 9% and 8%, were obtained under the treatment mode E=2 kV·cm−1, t=30 s. Pre-sowing electrostimulation of winter rape seeds at optimal conditions helps to increase its field germination. Under the treatment mode E=2 kV·cm−1, t=30 s was 90%, and with E=3 kV·cm−1, t=30 s – 83% versus 79.7% in the control.

Synthesis and characterization of P3HT:ZnO-FWCNTs for possible application in organic solar cells

Zinc oxide (ZnO) and few-walled carbon nanotubes (FWCNTs) mixed in poly(3-hexylthiophene-2,5-diyl) (P3HT) were prepared for application in organic solar cells (OSCs) as photoactive materials. ZnO was synthesized by microwave-assisted sol-gel method. Improved properties were found for the nanocomposite with 3 wt% of FWCNTs concentration. XRD revealed the hexagonal wurtzite structure of ZnO and the nanocomposites (ZnO-FWCNTs) showed both hexagonal wurtzite and carbon structure. UV/Vis/NIR and PL studies revealed a relatively higher photon absorption efficiency and emission intensity from the ZnO-3% FWCNTs. PL intensity of P3HT was quenched from the sample P3HT:ZnO-3% FWCNTs with the ratio of 1:1, indicating charge transfer phenomena between the electron donor (P3HT) and an acceptor (ZnO-FWCNTs) materials. FESEM showed well-mixed ZnO nanorods with P3HT. Current-voltage measurements indicated an improved electrical conductivity for P3HT:ZnO-3% FWCNTs (ratio 1:1). The obtained results suggest that this sample can potentially improve the photoelectrical conversion efficiency of the OSCs.

Uncertainty and covariance matrix of the coincidence-summing correction factors due to decay-data uncertainties

The uncertainty component of high efficiency gamma-ray spectrometry measurements due to the uncertainty of the decay parameters is evaluated. It is based on the analysis of a large set of random decay schemes, constructed using the values and uncertainties of the decay parameters taken from data libraries. The distributions of the coincidence-summing correction factors FC, of the factors p⋅FC (p = photon emission intensity), and of the correlations between the distribution of pairs of these factors are constructed and analysed.

Impact analysis of different applications of cyantraniliprole on control of horse chestnut leaf miner (Cameraria ohridella) larvae supported by biophoton emission

Cameraria ohridella is one of the most invasive pests of horse chestnut. Cyantraniliprole is one of the most perspectively active insecticides, which can transport within the plant in several ways, and its efficacy against this pest has not yet been tested. All three modes of application were effective against the target pest, but there was a difference in the time of action between them. However, no demonstrable difference in the speed of action was detected between the doses used. A more intense rate of acropetal translocation was confirmed compared to basipetal translocation. A trend-like effect between the applied concentration of cyantraniliprole and the photon emission intensity per unit area of plant tissue was observed in the translaminar and acropetal treatment settings. In both cases, a clear increase in photon emission was observed, indicating metabolic upregulation. Therefore, we can conclude that biophoton emission measurements can be utilized to conduct efficient pesticide translocation investigations.

Stability of breakdown phenomenon in N2, SF6, and their mixture under impulse voltages

In the self-breakdown experiment, it is demonstrated that the breakdown stability of 15% SF6/N2 was higher than that of pure SF6 and N2 in the non-uniform field under negative impulse voltages. In this paper, the stable breakdown phenomenon of the gas mixture is studied at the nanosecond scale. The corona process and streamer process of these three gases are investigated by using a high-speed framing camera. The stabilized corona and the abnormal streamer phenomena observed in the gas mixture discharge have a relation to the stable breakdown phenomenon. The stabilized corona is supposed to be the main reason that obstructs the development of negative steamer and stabilizes the supply of photons to the anode. Furthermore, the captured images of the streamer process in the gas mixture show that there is a negative ion sheath between the electrodes. The sheath keeps the corona stabilized near the cathode tip. In addition, photons emitted by the stabilized corona can ionize neutral particles near the anode. The generated photoelectrons and positive ions accumulate near the anode surface. The positive streamer occurs once the accumulation number reaches a certain value. In addition, the photon emission intensity and stability also have an influence on the stability of the positive streamer.

Determination of absolute Np L x-ray emission intensities from 241Am decay using a metallic magnetic calorimeter

Photon emission intensities of radionuclides, i.e. the number of emitted photons per decay, are the single most important decay data when the photon spectrometry technique is employed in ionizing radiation metrology. However, their precise measurement is problematic because they are usually determined by photon spectrometry with spectrometers having a detection efficiency calibrated with x-ray and γ-ray emission intensities from other radionuclides. Therefore, these intensities are ultimately interdependent and correlated to some extent. A novel method was applied to determine the photon intensities of α-emitting radionuclides by measuring the ratio between the rate of photons in the full energy peaks and the rate of detected α-particles with the same detection set-up. Thus, there is no need to calibrate the detection efficiency and to standardize calibration sources by primary methods. The main condition to reach low uncertainties is to have a spectrometer with an intrinsic detection efficiency close to unity for the measured photons and α-particles. This condition was fulfilled by a metallic magnetic calorimeter (MMC) with an intrinsic efficiency of around 99% between 5 keV and 25 keV. In addition, the MMC provides an ultra-high energy resolution of 28 eV (full width at half maximum), facilitating the processing of the spectrum. The method was applied to determine L x-ray emission intensities from the decay of 241Am(α) → 237Np emitted between 11.9 keV and 22.4 keV. A total L x-ray emission intensity of 37.90 (12) per 100 disintegrations was obtained; the value agrees well with previous measurements and has a lower uncertainty. The uncertainties of the L x-ray groups Lα, Lηβ and Lγ were improved by a factor of two. Moreover, due to the high-energy resolution of 28 eV, a detailed set of 33 L x-ray emission intensities are provided.

Detailed Successive Layer Modeling and Design Factor Analysis for Single Micro-LED Pixel

The major factors associated with the manufactured structures and photon emission intensity distribution must be accurately identified for the complicated optical design parameters associated with micro-LED pixels. This study presents the methodologies and reveals the sequential calculating protocol in each layer for pixel-level optical simulations, based on which the boundary condition errors associated with common optical simulations can be corrected. Moreover, the optical effect on each epitaxial layer of the micro-LED design is revealed, and the rationality of the setting of the finite-radius receiver with a pseudo-extended substrate material is also explained with respect to the intrinsic and extrinsic pixel-intensity distribution properties. Finally, the design of experiments DOE L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">18</sub> orthogonal array table is demonstrated by the Taguchi method to explore the principal factors for the parameter design of the micro-LED layers. The results indicate that the sapphire thickness, the P-GaN layer, the buffer layers, and an additional substrate plate are the four significant factors that primarily influence the luminous power and the corresponding uniformity on the exit pupil of micro-LEDs. Based on the luminous power uniformity, the signal-to-noise ratio in the sapphire thickness is 16.9, and the extended substrate plate is 9.8, which is ∼10 times > the interaction design parameter, such as the etching angle and reflective index of the extended substrate of the micro-LED pixel. These specific design factors can be the major optimization parameters for cost control and performance improvement.

Probing Majorana bound states via a pn junction containing a quantum dot

We propose an alternative route to transport experiments for detecting Majorana bound states (MBSs) by combining topological superconductivity with quantum optics in a superconducting $pn$ junction containing a quantum dot (QD). We consider a topological superconductor (TSC) hosting two Majorana bound states at its boundary ($n$ side). Within an effective low-energy model, the MBSs are coherently tunnel-coupled to a spin-split electron level on the QD which is placed close to one of the MBSs. Holes on the QD are tunnel-coupled to a normal conducting reservoir ($p$ side). Via electron-hole recombination, photons in the optical range are emitted, which have direct information on the MBS-properties through the recombined electrons. Using a master equation approach, we calculate the polarization-resolved photon emission intensities (PEIs). In the weak coupling regime between MBSs and QD, we find an analytical expression for the PEI which allows to clearly distinguish the cases of well separated MBSs at zero energy from overlapping MBSs. For separated MBSs, the Majorana spinor-polarization is given by the relative widths of the two PEI peaks associated with the two spin states on the QD. For overlapping MBSs, a coupling to the distant (nonlocal) MBS causes a shift of the emission peaks. Additionally, we show that quasiparticle poisoning (QP) influences the PEI drastically and changes its shot noise from super-Poissonian to sub-Poissonian. In the strong coupling regime, more resonances emerge in the PEI due to spin-mixing effects. Finally, we comment on how our proposal could be implemented using a Majorana nanowire.

Design of an ultra-sensitive and miniaturized diamond NV magnetometer based on a nanocavity structure

The ensemble of nitrogen-vacancy (NV) centers in diamond allows for the potential realization of the sensitive magnetometers by leveraging their excellent spin properties. However, the NV-based magnetometers are limited by their experimental magnetic field sensitivity owing to its inefficient photon collection. Moreover, they are a disadvantage to the reduced spatial resolution and excessive excitation power. To overcome these issues, we propose a ultra-sensitive diamond magnetometer based on nanocavities. The device structure can attain a high collective efficiency and enhance the photon emission intensity of the NV ensemble. This device can allow the efficient photon collection even when considering the positional distribution of the NV centers. Our theoretical analysis indicates that the minimum expected sensitivity is 60 fT/ The proposed design can achieve a volume-normalized sensitivity of 0.92 aT/ along with the required power of 7 μW, both of which are superior to those of bulk diamond. The proposed approach offers a promising route towards highly sensitive and energy-efficient magnetometers.

Determination of L-X ray absolute emission intensities of 238Pu, 244Cm, 237Np and 233Pa radionuclides using a metallic magnetic calorimeter

Energy dispersive photon spectrometry is a common analysis technique to quantify radionuclides present in a sample, the analysis is based on the knowledge of the photon emission intensities specific to each radionuclide. Among them, actinides have in general intense emission of L X-rays during the decay. However, their emission intensities are not well known and not detailed in the nuclear and atomic data tables due to the complexity of their spectra that cannot be resolved by conventional semiconductor spectrometers. Using a dedicated high energy resolution cryogenic detector, based on metallic magnetic calorimeter sensor technology, the L X-ray spectra of the decays of 238Pu(α) → 234U, 244Cm(α) → 240Pu, 237Np(α) → 233Pa and 233Pa(β−) → 233U were measured with an energy resolution between 23 eV and 43 eV (full width at half maximum) given access to an unprecedented level of detail.Moreover, the detector was conceived to provide a quasi-constant efficiency in the energy range of the L X-rays, minimizing the uncertainty for relative L X-ray emission intensities. Prior to the measurements, the full energy peak efficiency was carefully characterized, which enabled the determination of absolute emission intensities, with an uncertainty of the order of 1%. Some corrections had to be introduced using Monte Carlo simulations, in particular to take into account the surface activity inhomogeneities of the sources. Total and group L X-ray emission intensities are compared with the available data and with the recommended values. In addition, nearly 30 individual L X-ray intensities are presented.

Numerical optimization of transmission bremsstrahlung target for intense pulsed electron beam

The optimization of a transmission type bremsstrahlung conversion target was carried out with Monte Carlo code FLUKA for intense pulsed electron beams with electron energy of several hundred keV for maximum photon fluence. The photon emission intensity from electrons with energy ranging from 300 keV to 1 MeV on tungsten, tantalum and molybdenum targets was calculated with varied target thicknesses. The research revealed that higher target material element number and electron energy leads to increased photon fluence. For a certain target material, the target thickness with maximum photon emission fluence exhibits a linear relationship with the electron energy. With certain electron energy and target material, the thickness of the target plays a dominant role in increasing the transmission photon intensity, with small target thickness the photon flux is largely restricted by low energy loss of electrons for photon generation while thick targets may impose extra absorption for the generated photons. The spatial distribution of bremsstrahlung photon density was analyzed and the optimal target thicknesses for maximum bremsstrahlung photon fluence were derived versus electron energy on three target materials for a quick determination of optimal target design.

Determination of the half-life and the absolute photon emission intensities for the main gamma-ray energies of 124I

The National Institute of Standards and Technology (NIST) performed new standardization measurements for 124I. As part of this work the absolute photon emission intensity for the main gamma-rays of 124I were determined using several high-purity germanium (HPGe) detectors. In addition, the half-life for 124I was also determined using an HPGe detector. Ionization chamber measurements were performed for additional sources, but it was not possible to obtain a precise half-life value.

Measurement of the absolute gamma-ray emission intensities from the decay of 103Pd

Palladium-103 decays through electron capture to excited levels of 103Rh, and especially to the 39.748-keV metastable state. A high activity palladium chloride solution was standardized by liquid scintillation, using the Triple-to-Double Coincidence Ratio method. The absolute photon emission intensities were determined by gamma-ray spectrometry using point sources prepared with the standard solution. Different detectors and measuring conditions were used to cross-reference the results. The most intense photon emission intensities are derived with about 1% relative combined standard uncertainty.

Application of RRLC-QTOF-MS-based metabonomics and UPE for investigating Spleen-Qi deficiency syndrome with Panax ginseng treatment

Ethnopharmacological relevanceSpleen-Qi deficiency is a syndrome of traditional Chinese medicine. Panax ginseng (ginseng) is well known as the key herb for replenishing Qi and tonifying Spleen. However, the pathogenesis of Spleen-Qi deficiency syndrome and therapeutic mechanism of ginseng on Spleen-Qi deficiency constitution have not yet been entirely elucidated. Aim of the studyThe aim of this work was to investigate the pathogenesis of Spleen-Qi deficiency syndrome and therapeutic mechanism of ginseng on Spleen-Qi deficiency constitution. Materials and methodsThe urinary metabonomics was investigated before and after ginseng treatment in Spleen-Qi deficiency subjects by rapid resolution liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (RRLC-QTOF-MS). The spectra of metabolites were analyzed by principal component analysis (PCA) and the score showed significant difference among the three different groups. The serum biochemical parameters creatine kinases (CK), lactate dehydrogenase (LDH), interferon-γ (INF-γ), Interleukin-4 (IL-4), superoxide dismutase (SOD) and malondialdehyde (MDA) were determined by assay kits. In addition, ultraweak photon emission (UPE) intensity was measured at dazhui point in each subject. ResultsAccording to the orthogonal partial least-squares discriminant analysis (OPLS-DA) results and biochemistry databases searching, 15 potential biomarkers were identified to be involved in Spleen-Qi deficiency syndrome and ginseng influenced Spleen-Qi deficiency. The metabonomics and biological experiment data indicated that metabolism pathways were corresponding to energy metabolism, amino acid, carbohydrate, lipid and pyrimidine metabolisms, oxidative stress urea cycle, and intestinal flora metabolism. And the UPE intensity decreased significantly after the treatment. ConclusionsGinseng could promote the related metabolisms in Spleen-Qi deficiency constitution and the metabolites and UPE intensity may be useful as potential biomarkers for diagnosing and monitoring for Spleen-Qi deficiency syndrome.

Photoluminescence from Suspended and Supported Graphene

The thermal conductivity of suspended graphene varies greatly under light, but the thermal conductivity of supported graphene does not change as much as that of suspended graphene. This is due to the fact that all of the loaded graphene is placed on the substrate and the thermal diffusivity of the loaded graphene is very good. In this paper, the ultrafast properties of supported graphene and suspended graphene have been studied. Suspended graphene has unique thermal conductivity, and its thermal conductivity will change greatly with the increase of temperature. Because of graphene has no band gap, the photon emission of supported graphene cannot be realized by electron hole recombination as in direct band gap materials. Optical emission of hot carriers is possible in graphene, but usually inefficient. That’s because most materials have much faster thermal carrier relaxation time than radiation lifetime. Herein, the hot carrier emission of suspended graphene and supported graphene are studied by femtosecond laser. It is found that the hot carrier can reduce the relaxation time of hot carrier in suspended structure. The suspension structure does increase the intensity of photon emission.

A Smartphone-Based Whole-Cell Array Sensor for Detection of Antibiotics in Milk.

We present an integral smartphone-based whole-cell biosensor, LumiCellSense (LCS), which incorporates a 16-well biochip with an oxygen permeable coating, harboring bioluminescent Escherichia coli bioreporter cells, a macro lens, a lens barrel, a metal heater tray, and a temperature controller, enclosed in a light-impermeable case. The luminescence emitted by the bioreporter cells in response to the presence of the target chemicals is imaged by the phone’s camera, and a dedicated phone-embedded application, LCS_Logger, is employed to calculate photon emission intensity and plot it in real time on the device’s screen. An alert is automatically given when light intensity increases above the baseline, indicating the presence of the target. We demonstrate the efficacy of this system by the detection of residues of an antibiotic, ciprofloxacin (CIP), in whole milk, with a detection threshold of 7.2 ng/mL. This value is below the allowed maximum as defined by European Union regulations.

Ultrafast Photoluminescence from Suspended Gold/Graphene Hybrid Structures

Gold is a classical metal with the Fermi level lying in the sp-band, while graphene is a zero-bandgap semiconductor with Dirac band structure. Thus, the photon emission from both gold and graphene can not be effectively achieved by electron–holes recombination as direct bandgap semiconductors. Alternatively, optical emission from hot carriers is possible in graphene and gold, but usually with very low efficiency. This is because the hot carrier relaxation time is much faster than the radiative lifetime in both graphene and gold. To solve this problem, here we show that in suspended graphene structures the photon emission intensity can be enhanced by increasing the hot carrier relaxation time, while in suspended gold/graphene hybrid structures, the photon emission intensity also increased with increasing holes sizes. Since nowadays most semiconductor light sources are based on bandgap design and also restricted by it, the study could help to develop materials with the emission wavelength not being limited ...

Activity measurements and determination of nuclear decay data of 166Ho in the MRTDosimetry project

Holmium-166 is a high-energy β−-emitter radionuclide (~ 1.8 MeV) with a short half-life (~26.8h) that offers great potential as an alternative to 90Y for the treatment of liver cancer based on radioembolization. The possibility of quantitative Single Photon Emission Computed Tomography (SPECT) imaging of the main γ-ray emission at 80.6 keV, in addition to strong paramagnetic properties suitable for Magnetic Resonance Imaging (MRI), complement this therapeutic potential. The present paper describes the measurements carried out in three European radionuclide metrology laboratories for primary standardization of 166Ho and new determinations of X- and γ-ray photon-emission intensities in the framework of the European EMPIR project MRTDosimetry. New half-life measurements were also performed.