Half-peak Width Research Articles

Differences Between Far Electric Field Waveforms of Triggered Return Strokes and Natural Return Strokes From Nine Thunderstorms

The far electric field waveforms of natural first return strokes (FRSs), natural subsequent return strokes (SRSs), and triggered return strokes (TRSs) from nine thunderstorms measured by the same device were compared. The results were as follows: The far electric field peaks of TRSs were 31% smaller than that of SRSs. The geometric means of 10-to-90% risetime and half-peak width of SRS far electric fields are 2.4 μs and 5.4 μs, respectively, while those of TRSs are significantly smaller, i.e., 1.5 μs and 3.2 μs, respectively. Three possible reasons cause the differences between the SRS and TRS far electric field waveforms: TRS and SRS occur in different cloud conditions; triggering experiments are more likely to be successful when the thunderstorm electric field is in a stable period; the rise of the TRS current is steeper. Two possible reasons cause the steeper rise in TRS current: the lower part of the TRS channel is more conductive; the lower part of the TRS channel is shorter than that of the SRS channel.

Study of Solar Energetic Particle Events with Ulysses, ACE Observations and Numerical Simulations

We study the latitudinal extent of the near-relativistic electron events of 10 June 2000 and 26 December 2001, observed by both Ulysses and ACE. From the observations it is shown that the intensity of ACE was quite different from that of Ulysses. Through the numerical simulations, we obtain the SEPs time-intensity profiles, which generally fit well to the observations. To compare the observations we obtained the best fit parameters for the simulations. We suggest that the transport effects, especially the perpendicular diffusion effect, can cause the difference between the intensity profiles of ACE and Ulysses, which is dominated by particle transport at a large radial distance and high-latitude when a spacecraft has poor magnetic connection to the particle source. Furthermore, we present the particle source from the best fit parameters to show that the start and peak times of the particle sources are between the onset and max times of a flare in all the energy channels. Moreover, we propose models for the peak intensity and half width of the particle source, and the time interval from the flare onset to the particle source peak time. We show that the models generally agree with the best fit parameters.

The native and metastable defects and their joint density of states in hydrogenated amorphous silicon obtained from the improved dual beam photoconductivity method

In this study, undoped hydrogenated amorphous silicon (a-Si:H) thin films deposited under moderate dilution ratios of silane by radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) have been investigated using steady-state photoconductivity and improved dual beam photoconductivity (DBP) methods to identify changes in multiple gap states in annealed and light-soaked states. Four different gap states were identified in annealed state named as A, B, C, and X states. The peak energy positions of these Gaussian distributions are consistent with those recently identified by Fourier transform photocurrent spectroscopy (FTPS). After in situ light soaking, their density increases with different rates as peak energy positions and half-widths remain unaffected. The electron-occupied A and B states located below the dark Fermi level and their density and ratios in the annealed and light-soaked states correlate well with those defects detected by time-domain pulsed electron paramagnetic resonance (EPR) experiments. The A, B, and X states located closer to the middle of the bandgap anneal out at room temperature in dark and define the “fast” states. However, the C states show no sign of room temperature annealing such that they must define the “slow” states in undoped a-Si:H. The results found in this study indicate that the anisotropic disordered network is a more appropriate model than previously proposed defect models based on the continuous random network to define the nanostructure of undoped a-Si:H, where multiple defects, D0 and non-D0 defects, can be identified by using the improved DBP method.

Mechanistic regulation of gram-scale synthesis of triple emission cyanobacteria-based carbon dots and visual ratiometric sensing applications

Multi-peak emission is one of the most attractive properties of carbon dots (CDs). However, the mechanism of multi-peak emission is still not clearly explained, especially for biomass-derived CDs. Herein, we use cyanobacteria as carbon source, and prepare blue-light CDs and red-light CDs with triple emission via a facile microwave hydrothermal route. The CDs maintain stable and efficient fluorescence in solid state (QYs = 41.76%, 14.03%) with narrow half-peak widths of 74 and 30 nm. The experiment greatly improves the synthesis yield of CDs (40%), and expanding the experimental scale fivefold to achieve the gram-scale production. In-depth mechanism analysis revealed that the introduction of alkali can increase the self-doping content of N in CDs and convert pyrrolic N into graphitic N, further forming a hydroxyl shell on the surface of CDs. The synergistic effect of hydroxyl groups and graphitic N could adjust the energy gap, and triple-peaked emitting R-CDs are obtained. R-CDs are successfully applied to the visual ratiometric fluorescence sensor for Pb2+, which has a large linear range of 0–50 μM, 100–300 μM and a low lower detection limit of 0.85 μM. And R-CDs show a significant linear enhancement from pH 7 to 12,indicating R-CDs potential in the sensor field.

Determination of the standard rate constant for soluble-soluble quasi-reversible electrochemical systems by linear sweep voltammetry: Application to the electrochemical oxidation on screen-printed graphite electrodes

Semi-analytical approach was used for modeling and establishing Linear Sweep Voltammetry (LSV) profiles in the case of quasi-reversible electrochemical reactions involving soluble species. The effects of charge transfer coefficient (α) and dimensionless kinetic rate constant (Λ) on the shape and position of voltammograms were investigated. The combined effect on the LSV responses, peak current, half peak width and peak potential was also analyzed qualitatively and quantitatively. Kinetic curves were constructed in the form of the change in the LSV characteristics as a function of (α, Λ) and then modeled by the interpolation functions. The obtained equations are an easy-to-use tool in order to calculate the heterogeneous kinetic rate constant for quasi-reversible charge transfer. Experimental-theory validation has been performed on ferrocyanide oxidation on screen-printed graphite electrodes.

Electrohydrodynamic Printing of PCL@CsPbBr3 Composite Fibers with High Luminescence for Flexible Displays

Metal halide perovskite quantum dots (PQDs) are widely used in the display field due to their excellent photoelectric properties, such as ultra-narrow half-peak widths and ultra-pure luminescence color purity. Inkjet printing, laser direct writing and electrospinning are all common methods for PQDs printing to prepare micropattern displays. In order to produce large-scale and high-resolution PQDs micropatterns, electrohydrodynamic (EHD) printing technology is capable of large-scale deposition of highly oriented nanofibers on rigid or pliable, flat or bent substrates with the advantages of real-time regulation and single control. Therefore, it has a lot of potential in the fabrication of pliable electronic devices for one-dimensional ordered light-emitting fibers. Polycaprolactone (PCL) as an EHD printing technology polymer material has the advantages of superior biocompatibility, a low melting point, saving energy and easy degradation. By synthesizing CsPbBr3 quantum dots (QDs) and PCL composite spinning stock solution, we used the self-built EHD printing platform to prepare the PCL@CsPbBr3 composite light-emitting optical fiber and realized the flexible display of high-resolution micropatterns in polydimethylsiloxane (PDMS) packaging. An x-ray diffractometer (XRD), scanning electron microscope (SEM) and photoluminescence (PL) were used to characterize and analyze the fiber’s morphology, phase and spectral characteristics. EHD printing technology may open up interesting possibilities for flexible display applications based on metal halide PQDs.

Study of the electronic effect and quantitative spectra predictions of o-methoxyaniline-terminated monoazonaphthols: a combined experimental and DFT study.

A combined experimental and density functional theory (DFT) study on the UV-Vis spectra of o-methoxyaniline-terminated mono azo dyes was conducted. By applying time-dependent-DFT calculations, details of excitation processes were determined and visualization by hole-electron analysis was undertaken. Fragment-divided analysis revealed the contributions of different parts of the structures for the UV-Vis spectra, that richer/poorer electron density on aromatic rings lead to greater/less maximum absorption wavelengths (λmax) and larger/smaller half peak width (W1/2). Combining theoretical prediction with experimental verification, we answered the question of how the electronegativities of substituents affected the electron densities and how it affected the spectra. In addition, a linear model connecting the λmax and W1/2 to the chemical shifts obtained by NMR spectroscopy was constructed, which laid the foundation for construction of a spectral library.

Growth and spectral properties of Pr,Yb,Ho:GdScO<sub>3</sub> crystals

In order to explore and develop new crystal materials in the 2.7~3 μm band, Pr,Yb,Ho:GdScO<sub>3</sub> crystal were successfully grown by the Czochralski method for the first time. X-ray diffraction measurement was performed to obtain powder diffraction data. Raman spectra were measured and the vibration peaks were identified. The transmission spectrum, emission spectrum and fluorescence lifetime of Pr,Yb,Ho:GdScO<sub>3</sub> crystal were also characterized. The center of the strongest absorption band is at 966 nm with the half-peak width 90 nm, which comes from the transition of Yb<sup>3+</sup>: <sup>2</sup>F<sub>7/2</sub>→<sup>2</sup>F<sub>5/2</sub>. The absorption cross section of Yb<sup>3+</sup> were calculated and the values at 966、973、985 nm are 0.62×10<sup>-20</sup>, 0.60×10<sup>-20</sup> and 0.58×10<sup>-20</sup> cm<sup>2</sup>respectively. The maximum emission peak is at 2850 nm and the half-peak width is 70 nm, the lifetimes of Ho<sup>3+</sup>:<sup>5</sup>I<sub>6</sub> and <sup>5</sup>I<sub>7</sub> were measured to be 1094 μs and 56 μs respectively, and the emission cross section at 2850 and 2935 nm were calculated to be 3.6×10<sup>-20</sup>cm<sup>2</sup> and 1.21×10<sup>-20</sup> cm<sup>2</sup>. Compared with Yb,Ho:GdScO<sub>3</sub> crystal, the absorption peak of Yb<sup>3+</sup> and the emission peak were both broadened, which are related to the increase of crystal disorder. The lifetime of the lower energy level decreases significantly. Furthermore, the energy transfer mechanism between Ho<sup>3+</sup> and Pr<sup>3+</sup> was analyzed, and the energy transfer efficiency between Ho<sup>3+</sup>:<sup>5</sup>I<sub>7</sub> and Pr<sup>3+</sup>:<sup>3</sup>F<sub>2</sub>+<sup>3</sup>H<sub>6</sub> was calculated to be 99%, which is higher than that in other materials. All the results show that Pr,Yb,Ho:GdScO<sub>3</sub> crystal is an excellent 2.7~3 μm laser material, and is easier to achieve laser output than Yb,Ho:GdScO<sub>3</sub> crystal.

Comparison of electrophysiological properties of parvalbumin neurons in the tail of the striatum and the auditory cortex of mice

To study the electrophysiological properties of parvalbumin (PV) neurons in the auditory cortex (AC) and its descending auditory projection area in the tail of the striatum (TS). The stimulation response of PV neuron step current was recorded in PV-Cre-Ai14 mice using in vitro patch clamp technique, and the release characteristics and waveform characteristics of PV neuron action potentials (APs) were analyzed using Clampfit and MATLAB software. The release characteristics of the APs included AP onset, rheobase, average firing rate, F/I slope and spike frequency adaptation (SFA); the waveform characteristics included peak and post potential characteristics. The PV neurons of the TS and the AC had significantly different electrophysiological characteristics. In terms of peak potential characteristics, the PV neurons in the TS presented with smaller half peak width (P < 0.001) and larger amplitude (P < 0.01) with larger maximum ascending slope (P < 0.01) and maximum descending slope (P < 0.05). For post potential characteristics, the PV neurons in the TS showed a greater post hyperpolarization (P < 0.01) with a shorter time for recovery of the resting potential (P < 0.01). The firing characteristics of the PV neurons of the TS featured a higher AP rheobase (P < 0.01), a larger F/I slope (P < 0.01), a greater firing onset delay (P < 0.001), and a larger SFA (P < 0.01). The PV neurons in the TS and the AC of mice show significantly different electrophysiological characteristics in processing auditory information.

Ball milling synthesis and optical properties of Na and Bi ions Co-doped double perovskite Cs2AgInCl6

Double perovskite Cs2AgInCl6 is a new direct band gap semiconductor material. Compared with traditional perovskite CsPbX3 (X = Cl, Br, I), double perovskite Cs2AgInCl6 has good stability and wide fluorescence half peak width. This study reports the mechanochemical synthesis, characterization and application of a lead-free double perovskite Cs2AgInCl6 doped with Na and Bi ions. It was found that through a facile room temperature mechanical ball milling process, the double perovskite structure can be obtained within 30 min. Then, Na and Bi ions were used to dope to optimize its luminescence properties. By this synthesis method, the sample with the best doping ratio obtained in the experiment is Cs2Ag0.7Na0.3In0.9Bi0.1Cl6 with the photoluminescence quantum yield (PLQY) of 32.7%. The X-ray diffraction (XRD) and photoluminescence (PL) results show that Na and Bi ions can promote the crystallization and optimize the luminescence properties of Cs2AgInCl6. The theoretical calculation results show that both conduction band minimum (CBM) and valance band maximum (VBM) of Cs2Ag0.7Na0.3In0.9Bi0.1Cl6 are flat, which is favorable for the generation of self-trapped excitons. Packaging Cs2Ag0.7Na0.3In0.9Bi0.1Cl6 sample on an ultraviolet (UV) LED chip, and a warm white LED with good performance can be obtained, which shows a bright potential application in the field of white LED.

Mn2+ doped BaAl11O16N phosphors with narrow band green emission and superior thermal stability for backlighting display applications

Here, BaAl11O16N: Mn2+ green phosphor was synthesized by a two-step high-temperature solid-phase method, and its phase structure, morphology and photoluminescence properties were studied in detail. The phosphor has a wide excitation range of 240–500 nm, and the most effective excitation bands are in the blue spectral regions, indicating that BaAl11O16N: Mn2+ green phosphor can be effectively excited by the commercial blue LED chip. Under the excitation of ultraviolet and blue light, the BaAl11O16N: Mn2+ phosphor shows bright green light emission, with a peak of 514 nm and a half peak width of about 31 nm. The emission properties with temperature change show that the BaAl11O16N: Mn2+ phosphor has good thermal stability and excellent color stability. The white light-emitting diode (a blue InGaN chip combined with BaAl11O16N: 0.25Mn2+ phosphor and a commercial K2SiF6: Mn4+ phosphor) exhibits a NTSC value of 119.3%. Therefore, it can be concluded that the BaAl11O16N: Mn2+ phosphor the ideal choice for wide color gamut backlight as a potential efficient phosphor with green narrow-band emission.

Improvement the near-infrared luminescence properties of double perovskite phosphor La(Mg0.5Sn0.5In0.5Sc0.5)0.5O3:Cr3+ via co-doping Yb3+

In recent years, the broadband near-infrared (NIR) spectroscopy technology has been widely used in the field of nondestructive testing. However, these existing NIR phosphors showed relatively short emission wavelengths, narrower half-maximum full-width (FWHM), and narrower half-peak widths, importantly, few phosphors presented the emission from 950 nm to 1100 nm. In order to solve these problems, the Yb3+/Cr3+ ions codoped La(Mg0.5Sn0.5In0.5Sc0.5)0.5O3 (LMSIS) was synthesized by the solid-state method, and the emission spectrum of LMSIS:Cr3+ can be extended to the NIR long-wave region due to the energy transfer of Yb3+ and Cr3+, and the thermal stability of the phosphor can be improved due to the inherent temperature stability of the Yb3+ f-f transition. The NIR phosphor converted light emitting diodes (pc-LEDs) were fabricated by combining the LMSIS:0.003Cr3+, 0.0015Yb3+ with blue LED chip, which can be expected to be used in the field of broadband near-infrared non-destructive detection.

Deconvolution of overlapping peaks in ion mobility spectrometry based on a multiobjective dynamic teaching-learning-based optimization.

Because of its powerful analytical ability, ion mobility spectrometry (IMS) plays an important role in the field of mass spectrometry. However, one of the main defects of IMS is its low structural resolution, which leads to the phenomenon of peak overlap in the analysis of compounds with similar mass charge ratio. A multiobjective dynamic teaching-learning-based optimization (MDTLBO) method was proposed to separate IMS overlapping peaks. This method prevents local optimization and identifies peak model coefficients efficiently. In addition, the position information of particles largely reflects the half-peak width of IMS, which makes single peaks difficult to appear and coefficient identification easier. The performance comparison of MDTLBO with other deconvolution methods (genetic algorithm, improved particle swarm optimization algorithm, and dynamic inertia weight particle swarm optimization algorithm) shows that the maximum deconvolution error of MDTLBO is only 0.7%, which is much lower than that for the other three methods. In addition, robustness is a performance index that reflects the advantages and disadvantages of the algorithm. MBTLBO is more robust than other algorithms for separating overlapping peaks. The algorithm can separate the heavily overlapped mobility peaks, produce better analysis results, and improve the resolution of IMS.

Br-doping mediated band-gap engineering contributed Bi/Bi2O2CO3 nano-platelets with enhanced photocatalytic performance

Photocatalyst modification by energy level engineering is of great significance for the generating of active free radical. In this work, a novel strategy was employed to construct Br-doped Bi2O2CO3 followed by in situ reduction deposited Bi nanoparticles on the surface of Bi2O2CO3 component. Therein, the doping of Br regulated the energy level structure of Bi2O2CO3. The characterization of SEM and TEM intuitively displayed the morphology changes among Bi2O2CO3, Br-Bi2O2CO3 and Br-Bi/Bi2O2CO3 in size and thickness, while XRD illustrated that the decrease in shape was consistent with the increase in the half-peak width of the Br-doped samples. The Tauc spectrum verified that the bandgap of Br-Bi/Bi2O2CO3 nanosheets was obviously narrowed, and after Bi nanoparticles were deposited on the surface of Bi2O2CO3 by in-situ reduction of Bi3+ with glucose, the absorption of visible light was enlarged distinctively. Excitingly, the kinetic constant of Br-Bi/Bi2O2CO3 sample was 7.22 times higher than that of Bi2O2CO3, showed excellent photocatalytic performance on degrading of tetracycline. The liquid chromatography-mass spectrometry (LC-MS) was employed to deduce the possible degradation routes, and then the toxicity of tetracycline and its degradation intermediates were analysed based on quantitative structure activity relationship (QSAR).

Authenticity Assessment from Sesame Seeds to Oil and Sesame Products of Various Origin by Differential Scanning Calorimetry.

The aim of this study was to conduct thermal characterization of sesame seeds and oils from various geographical origins (Ethiopia, India, Nigeria, Sudan, Turkey), different method of extraction (hexane and cold-pressing), and different types of derived products (halva and tahini). Thermal characterization was investigated using differential scanning calorimetry (DSC), which showed that origin of the seeds has no influence on the melting profile of sesame oil (peak temperature and enthalpy). Method of extraction (hexane and cold-pressing) influenced the peak temperatures of the resulting oils (p ≤ 0.05). The addition of 20% of palm olein to pure sesame oil influenced the significant changes in thermodynamic parameters such as peak temperature (Tm2), which was lowered from -5.89 °C to -4.99 °C, peak half width (T1/2), elevated from 3.01 °C to 4.52 °C, and the percentage of first peak area (% peak 1) lowered from 87.9 to 73.2% (p ≤ 0.05). The PCA method enabled to distinguish authentic and adulterated sesame oils of various origins. There were no significant differences in thermal properties among the products (halva, tahini) and the authentic sesame oil (p &gt; 0.05). The obtained results showed DSC feasibility to characterize sesame oil and sesame products in terms of authenticity.

Susceptibility of multipactor discharges near a dielectric driven by a Gaussian-type transverse rf electric field

Multipactor discharge near an rf window is a key limiting factor in high power microwave systems. In this work, we report special features of dielectric multipactor susceptibility under a Gaussian-type waveform as a function of the rf power density of the transverse rf electric field (P¯rf) and normal restoring field (Edc) via particle-in-cell (PIC) and multiple particle Monte Carlo (MC) simulations. The MC simulations show that, for a Gaussian waveform of a half peak width (Δτ), larger than Δτ/T=0.15 with T = 1 ns the rf repetition period, the susceptibility boundary is similar to that of the conventional sinusoidal waveform-driven multipactor, i.e., two inclined lines in the plane of (P¯rf,Edc). However, by decreasing Δτ, the susceptibility boundary converts to be a closed curve at Δτ/T=0.11 in the plane of (P¯rf,Edc) and further shrinks at Δτ/T=0.05. PIC simulations with a self-consistent surface and space charge effects also show a reduced Edc with increasing P¯rf when P¯rf exceeds a critical value, resulting in a closed curve in the plane of (P¯rf,Edc), and the maximum time-averaged Edc (multipactor strength) also decreases significantly with further decreasing Δτ in agreement with MC simulations. Accordingly, the fraction of the rf power density absorbed by the multipactor discharges also decreases nonlinearly with Δτ from the order of 10−2 to 10−3 (even 10−4), implying a significant improvement compared to the conventional sinusoidal waveform. The simulations also show that the multipactor susceptibility under a transverse Gaussian-type waveform for different frequencies follows the same scaling law in terms of the ratio of the electric field to the rf repetition rate.

Experimental study on morphology, nanostructure and oxidation reactivity of particles in diesel engine with exhaust gas recirculation (EGR) burned with different alternative fuels

Experiments were conducted at a diesel engine with exhaust gas recirculation (EGR), and the particulates produced by the combustion of Fischer-Tropsch (F-T) diesel, biodiesel as well as diesel were collected. The influences of fuel characteristics upon the morphology, nanostructure and oxidation reactivity of particles were explored by high-resolution transmission electron microscope (HRTEM), Raman spectroscopy (RS) and thermogravimetry (TGA). The results show that compared with diesel, F-T diesel particulates possess smaller fractal dimension (Df) and fringe tortuosity (Tf), lower the area ratio of D1 peak to G peak (AD1/AG) and half peak width of D1 peak (D1-FWHM), longer fringe length (La), shorter separation distance (d), higher oxidation characteristic temperature and apparent reactive energy (Ea), while biodiesel particulates exhibit the opposite features. Among the samples, F-T diesel particulates display the highest graphitization degree and the lowest oxidation reactivity, biodiesel particulates present the most disorderly nanostructure and are more easily oxidized. The application of EGR increases the agglomeration degree, reduces the graphitization degree and oxidation characteristic temperature, and enhances the oxidation reactivity of particulate. Compared with the particulates collected without EGR, the Ea of FT diesel, biodiesel, and diesel particulates are reduced by 36.7%, 41.2%, and 37.5% as the EGR rate is 30%.

Auditory response patterns of mouse primary auditory cortex to sound stimuli

To investigate the auditory response patterns of mouse primary auditory cortex (A1) neurons. In vivo cell-attached recordings and neural network modeling were performed to detect the changes in response patterns of A1 neurons of awake C57BL/6J mice to sound stimulation with varying lengths. A1 neuron signals were recorded for 216 neurons in 20 awake mice using a target sound stimulation sequence, and the classification and response characteristics of A1 neuron response patterns were examined using post-stimulus spike time histograms. To simulate the diversity of the A1 neuron response patterns, an A1 neuron model was established based on the Wilson-Cowan model and integral-firing model. The neuron connection weight parameters in the model were calculated by examining the micro loop structure of the pyramidal neurons, parvalbumin neurons, and somatostatin neurons in the A1 region, and the A1 neural network information coding model was constructed. The Onset response neurons only had fast spike response within 10 to 40 ms after the beginning of noise stimulation (122 neurons). The Sustained response neurons had spike response continuously during the noise stimulation (26 neurons). The On-off response neurons had fast spike response after the beginning and the end of noise stimulation (40 neurons). The Offset response neurons only had fast spike response within 10 to 40 ms after the end of noise stimulation (22 neurons). In the neural network model, the Onset peak neural activities of A1 pyramidal neurons, parvalbumin neurons, and somatostatin neurons were 0.7483, 0.5236 and 0.9427, respectively, and their response half peak widths were 18.5 ms, 12 ms and 31 ms during the 100 ms noise stimulation, respectively. By changing the feedforward excitation and synaptic inhibition time constants in the model, the neurons generated numerous different types of spike train. The auditory response of mouse A1 neurons to sound stimuli shows mainly the Onset, Sustained, On-off, and Offset response patterns.

A statistical interpretation of the voltammetry of adsorbed substances under the perspective view of the Digital Video Electrochemistry

Coupling cyclic voltammetry with digital video electrochemistry allows identifying different electrochemical processes overlapped. Mathematical description of the time evolution of mean color intensities and their standard deviation at the studied electrode surface during voltammetric experiments were developed. Parallel electrochemical reactions and the presence of colored intermediate species was also evaluated. Single expressions for the shape of these curves, including the maximum of peaks or the half-peak widths are analyzed on the basis of a single layer covered electrode. The good similitude among current, mean color intensities derivative and variance curves allows a statistical interpretation for these processes.

Coherent backscatter enhancement in bistatic Ku- and X-band radar observations of dry snow

Abstract. The coherent backscatter opposition effect (CBOE) enhances the backscatter intensity of electromagnetic waves by up to a factor of 2 in a very narrow cone around the direct return direction when multiple scattering occurs in a weakly absorbing, disordered medium. So far, this effect has not been investigated in terrestrial snow in the microwave spectrum. It has also received little attention in scattering models. We present the first characterization of the CBOE in dry snow using ground-based and spaceborne bistatic radar systems. For a seasonal snowpack in the Ku-band (17.2 GHz), we found backscatter enhancement of 50 %–60 % (+1.8–2.0 dB) at a zero bistatic angle and a peak half-width at half-maximum (HWHM) of 0.25∘. In the X-band (9.65 GHz), we found backscatter enhancement of at least 35 % (+1.3 dB) and an estimated HWHM of 0.12∘ in the accumulation areas of glaciers in the Jungfrau–Aletsch region, Switzerland. Sampling of the peak shape at different bistatic angles allows estimating the scattering and absorption mean free paths, ΛT and ΛA. In the VV polarization, we obtained ΛT=0.4±0.1 m and ΛA=19±12 m at the Ku-band and ΛT=2.1±0.4 m and ΛA=21.8±2.7 m at the X-band, assuming an optically thick medium. The HH polarization yielded similar results. The observed backscatter enhancement is thus significant enough to require consideration in backscatter models describing monostatic and bistatic radar experiments. Enhanced backscattering beyond the Earth, on the surface of solar system bodies, has been interpreted as being caused by the presence of water ice. In agreement with this interpretation, our results confirm the presence of the CBOE at X- and Ku-band frequencies in terrestrial snow.