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oe1(光电查) - 科学论文

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出版时间
  • 2018
研究主题
  • circularly polarized (CP) antenna
  • Elliptical microstrip antenna (EPMA)
  • impedance bandwidth (IBW)
  • defected ground (DG) technique
  • multi-layered stacked structure
  • axial ratio bandwidth (ARBW)
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • Bhagwant University, Ajmer, Rajasthan, India
  • Govt Mahila Engineering College, Ajmer, Rajasthan, India
97 条数据
?? 中文（中国） ▾

  • Chiral Sensing Using Circularly Polarized Luminescence of Bis (phenanthroline dicarboxylic acid) Eu(III) Complex Induced by Allosteric-type Interaction with Amino Acid Molecules

    摘要： [Eu(pda)2]- and [Eu(bda)2]- (pda = 1,10-phenanthroline-2,9-dicarboxylic acid; bda = 2,2’ bipyridine 5,5’-dicarboxylic acid) have an achiral D2d structure in crystals. These complexes exhibit circularly polarized luminescence (CPL) in water containing chiral amino acids. In this work, induced CPL of [Eu(pda)2]- and [Eu(bda)2]- in water solutions containing a mixture of D- and L- amino acids were examined. Plots of glum values of the induced CPL as a function of mol-fraction of L- and D- arginine reveal that [Eu(pda2]- favors homo-association ([Eu(pda)2]--(L-arginine)2 or [Eu(pda)2]--(D-arginine)2) over hetero-association {[Eu(pda)2]--(L-arginine)?(D-arginine)}. This suggests that association of an arginine molecule induces a structural change in [Eu(pda)2]- to promote chiral selective association to another arginine, i.e., homo-allosteric association. On the other hand, the system of [Eu(pda)2]- with histidine favors hetero-allosteric association over homo-association. No allosteric effect is recognized in CPL from [Eu(bda)2]-.

    关键词： allosteric effect,amino acid,lanthanide complex,circularly polarized luminescence,chiral sensing

    更新于2025-09-23 15:22:29

  • Aggregation-amplified circularly polarized luminescence from axial chiral boron difluoride complexes

    摘要： The development of small organic molecules with intense and switchable circularly polarized luminescence (CPL) is currently attracting great interest due to their promising applications in chiroptical devices and sensors. In this paper, CPL-active BF2-bridged azaanthracene dimers (BA1 and BA2) were facilely synthesized by incorporating boron difluoride unit to the bi-naphthalene. BA1 and BA2 show moderate CPL in diluted solutions, however, BA2 exhibited aggregation-amplified red CPL with large dissymmetry factor up to 1.6×10?2. Moreover, acid-/base-triggered CPL switch off/on were also realized via disaggregation/aggregation of BA2 in tetrahydrofuran (THF)/water binary solvents.

    关键词： aggregation-induced emission,bodipy,circularly polarized luminescence,switch,dyes and pigments

    更新于2025-09-23 15:22:29

  • Self-Assembly of Amphiphilic Schiff Base and Selectively Turn on Circularly Polarized Luminescence by Al3+

    摘要： We designed glutamide-derived amphiphilic Schiff bases containing three different aldehyde moieties for the fabrication of circularly polarized luminescence (CPL) emitting materials. Upon self-assembly in acetonitrile, Schiff bases featuring 4-(dimethylamino)-2-hydroxylbenzaldehyde and 1-hydroxy-2-naphthaldehyde groups form supramolecular gels with twist and fiber structures, respectively, while Schiff bases featuring 2-hydroxy-1-naphthaldehyde groups forms precipitation with flakes structures. Although emission and circular dichroism (CD) signals can be detected from the supramolecular gels formed by amphiphilic Schiff bases, none of them exhibits circularly polarized luminescence (CPL). While Mg2+, Zn2+ and Al3+ can both significantly enhance the fluorescence of the Schiff bases, interestingly, only Al3+ ion is able to turn on the CPL emission. This study on the one hand provides a simple method to the fabrication of CPL emitting supramolecular materials, and on the other hand offers a novel way to the sensing of aluminum ion with supramolecular materials.

    关键词： Self-assembly,Schiff bases,Circularly polarized luminescence,Al3+,Supramolecular gels

    更新于2025-09-23 15:21:21

  • <i>l</i> -Stercobilin-HCl and <i>d</i> -Urobilin-HCl. Analysis of Their Chiroptical and Conformational Properties by VCD, ECD, CPL Experiments and MD, DFT Calculations

    摘要： Vibrational circular dichroism (VCD) and IR spectra of dichloromethane solutions of l-stercobilin and d-urobilin hydrochlorides have been recorded in the mid-IR region. The spectra are best interpreted by combining molecular dynamics (MD) calculations and DFT calculations within the QM/MM ONIOM-type framework, and the combined predicted results are better and more informative than the more standard analysis provided by DFT calculations. The same approach also sheds light on the Cotton effect sign inversion of room temperature versus low temperature electronic CD (ECD) spectra of the same compounds in methanol-glycerol solution. Finally, circularly polarized luminescence (CPL) spectra for l-stercobilin in chloroform solution provide information on the excited state geometry of this molecule.

    关键词： Vibrational circular dichroism,electronic CD,molecular dynamics,IR spectra,QM/MM ONIOM-type framework,Cotton effect,circularly polarized luminescence,DFT calculations

    更新于2025-09-23 15:21:21

  • A Low-cost Ka-band Circularly Polarized Passive Phased-Array Antenna for Mobile Satellite Applications

    摘要： This paper presents a low-profile, high-performance, and low-cost Ka-band circularly polarized (CP) passive phased-array antenna (PAA) system. A 1 × 4 passive sub-array operating at the Ka-band frequency band is investigated, developed, and tested as a possible building block for mobile satellite communication systems. In particular, a CP antenna integrated with a high-performance passive phase shifter is presented and experimentally verified. A new low-cost and low-profile magnetic actuator is proposed to precisely control the phase state of the phase shifter. A 3-D printed polymer package is utilized to enclose the phase shifter and reduce the environmental effects. The proposed CP passive PAA achieves high performance right hand circularly polarized (RHCP) radiation with high cross-polarization discrimination over a wide scan angle from 0o to ±38o over the frequency band (29.5-30.5 GHz). An AR < 3dB is demonstrated over the entire scanning range. Moreover, the measured radiation efficiency is 60% at bore-sight. The gain drops by 1 dB at ±38o scanning angles.

    关键词： satellite mobile communication,millimeter-wave phased-array antenna,phase shifter,Circularly polarized antenna

    更新于2025-09-23 15:21:21

  • The Novel W Parasitic Strip for the Circularly Polarized Microstrip Antennas Design and the Mutual Coupling Reduction between Them

    摘要： This paper presents a novel W shaped parasitic strip to design the circularly-polarized (CP) simultaneous transmit and receive (STAR) antennas and reduce the mutual coupling (MC) between them. By disturbing the current fields and inducing the current distribution on the antenna patches, the CP radiation and MC reduction are achieved. The designed CP antennas have 30 MHz 10-dB impedance bandwidth, 16 MHz 3-dB AR bandwidth and approximate 5.08 dBic peak CP gain. This technique also reduce the MC from ?7 dB to ?50 dB when the antennas are placed with a 0.18 λ0 center-to-center distance and a 0.033 λ0 edge-to-edge distance, where λ0 is the free-space wavelength. When achieving the MC reduction, the antenna radiation pattern restores to that of the isolated antenna. Furthermore, the antenna CP gain and efficiency is improved comparing those of the antenna without the parasitic strip or the classic corner cut CP antenna.

    关键词： closely spaced,circularly polarized,Mutual coupling reduction,parasitic strip

    更新于2025-09-23 15:21:21

  • The Design of Dual Circularly Polarized Series-Fed Arrays

    摘要： This paper presents the design of dual circularly polarized (CP) series-fed arrays based on Sequential rotation (SR) technique with uniform radiation elements. The radiation elements and feeding network used in the array are uniform, which leads to the possibility of dual-CP radiation by series-fed SR arrays. Meanwhile, the elements radiate unequal powers due to this arrangement. The relationship between the axial ratio (AR) and four key parameters of the array is derived and thoroughly discussed. Good polarization purity and port isolation can be realized by optimizing these parameters. A dual-CP array working at 10 GHz is designed with the help of the analysis. Experimental results show that the proposed antenna has good properties.

    关键词： Circularly polarized antenna,Series-Fed array,Sequential rotation,Dual circularly polarized,Antenna array,Axial ratio

    更新于2025-09-23 15:21:01

  • Intense circularly polarized attosecond pulse generation from solid targets irradiated with a two-color linearly polarized laser

    摘要： A method for the production of intense circularly polarized (CP) attosecond pulses from relativistic laser-solid interactions is proposed, where a two-color linearly polarized (LP) laser is used. The polarization, photon frequency, and other properties of the obtained attosecond pulse can be controlled by adjusting the ratio of the dichromatic driving LP field in different harmonics, which is much easier and more efficient than those previously using CP driving lasers. Both one- and two-dimensional particle-in-cell simulations show that a CP attosecond extreme-ultraviolet pulse with an intensity of 1.4 × 1019 W/cm2 and a duration of about 120 as is obtained by a two-color LP laser at intensities in the fundamental and second harmonics of, respectively, 1.5 × 1022 and 6.4 × 1021 W/cm2, which can be applied for the detection of the magnetic and chiral properties of materials.

    关键词： relativistic laser-solid interactions,attosecond pulse,two-color linearly polarized laser,circularly polarized,extreme-ultraviolet pulse

    更新于2025-09-23 15:21:01

  • Non-classically Controlled Sign in a 1.6 Tesla Magnetic Circularly Polarized Luminescence of Three Pyrenes in a Chloroform and a PMMA Film

    摘要： Molecular pyrene, 1-hydroxylpyrene, and 2-hydroxypyrene in chloroform and embedded in poly(methyl methacrylate) film reveal mirror-image magnetic circularly polarized luminescence (MCPL) when south (S)-up or north (N)-up direction of the longitudinal external magnetic field of 1.6 T to unpolarized incident light (Faraday geometry) is employed. The |gMCPL| magnitude is on the order of 10–3 T–1 in 374–416 nm. The sign of MCPL is controlled by the S-up and N-up geometry and by the position (1- or 2-) of the hydroxy group.

    关键词： magnetic circularly polarized luminescence,pyrene,chirality,fluorescence

    更新于2025-09-23 15:21:01

  • Influence of intensity ratio of the two driving laser fields on the cutoff of the high-order harmonics

    摘要： We investigate the high-order harmonic generation (HHG) of the helium atom at the various intensity ratios of the counter-rotating two-color circularly polarized laser fields. The results show that the cutoff energy of the harmonic spectra can be affected by changing the intensity ratios. By comparing the results from different intensity ratios, we find that the distances the electrons travel are short when the intensity ratio is increased. The dependence of the cutoff position in the HHG on the intensity ratios usually results from the classical trajectories of the electrons. As the intensity ratio increases, the electrons cannot be accelerated and it will gain less energy. As a result, the harmonic spectra are cut off at the lower energy. We compare the quantum and classical trajectories results to illustrate the reasons of the cut off dependence.

    关键词： intensity ratios,cutoff energy,high-order harmonic generation,two-colour circularly polarized laser fields

    更新于2025-09-23 15:21:01