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- 实验方案
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Highly Dispersive Nearly Free Electron Bands at a 2D-Assembled C <sub/>60</sub> Monolayer
摘要： Superatomic molecular orbitals (SAMO), which are atom-like diffuse orbitals formed at a molecule, play an important role in controlling the electronic functionality at one- to three-dimensional (1D–3D) assemblies of organic nanomaterials because they form highly dispersive and nearly free electron (NFE) bands, such as a bulk metal, by mixing their wavefunctions with neighbors. Herein, we identify a series of delocalized SAMOs at a two-dimensional assembled C60 fullerene monolayer utilizing resonant angle-resolved two-photon photoemission spectroscopy and theoretical calculations. SAMOs exhibit distinct NFE band dispersion characteristics to be hybridized between the diffuse orbitals at 2D-assembly, unlike the well-known frontier unoccupied π* orbitals with localized wave functions at the carbon framework of C60. Density functional theory (DFT) calculations for the NFE bands quantitatively reproduce the experimental observations including their energies and effective electron masses. These NFE bands comprising SAMOs above the Fermi level dominate charge transfer or photofunctional properties at the 1D–3D molecular assemblies, particularly when the band energies are lowered through a doping strategy.
关键词： Superatomic molecular orbitals,Two-photon photoemission,Fullerenes,2D-materials,Organic devices
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Annealing Influence on Structural and Luminescencent Properties of ZnSe:Fe
摘要： Zinc Selenide crystals doped with Iron are promising material to be used as an active media in tunable mid-IR lasers (4 ? 5 μm) [1]. The ZnSe:Fe lasing characteristics close to the theatrical maximum are obtained by optical excitation [2]. Nowadays other pumping methods are also being explored. Previously we have observed luminescence in the mid-IR spectral region with the maximum at the wavelength of 3.9 μm under electron-impact excitation. The present research is focused on the in?uence of annealing process in Zn atmosphere on defective-impurity compound (DIC) and intensity of mid-IR cathodoluminescence (CL). We studied DIC by two-photon confocal microscopy (TPCM) on Carl Zeiss LSM NLO 710 (commercially available equipment). The TPCM allows detecting edge luminescence (EL) (460-480 nm) and DIC (480 - 725 nm) as well as mapping luminescence distribution [3]. In the CL experiments, the crystals were excited by a pulsed electron gun with the accelerated electron energy of 36 kV [4]. A series of ZnSe single crystals doped with Fe by thermal diffusion from surface was subjected to the DIC and CL studies. The initial ZnSe plates were cut from boules grown from the melt by the Bridgman method with an addition of Tellurium. Iron concentrations varied from 0.01 to 14 wt.% as determined by XDR. The samples were observed by TPCM and CL before and after annealing in Zn atmosphere.
关键词： mid-IR lasers,ZnSe:Fe,two-photon confocal microscopy,cathodoluminescence,annealing
更新于2025-09-12 10:27:22
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Femtosecond laser fabrication of 3D templates for mass production of artificial compound eyes
摘要： Compound eyes are unique optical imaging systems that consist of numerous separate light-sensitive units (ommatidia). Attempts have been made to produce artificial compound eyes via advanced 3D nanotechnologies. Among them, femtosecond laser direct writing (FsLDW) technology has emerged as an effective strategy due to its distinct advantages in 3D designable and high precision fabrication capability. However, the point-by-point scanning process results in a very low fabrication efficiency, limiting the practical applications of the FsLDW technology. To solve this problem, we propose a high-efficiency method for the mass production of 3D artificial compound eyes using a photopolymer template fabricated by FsLDW. The resultant 3D SU-8 compound eye templates could be used to replicate polydimethylsiloxane (PDMS) compound eyes many times (over 50 times) with a highly improved efficiency (nearly 20 times higher than the efficiency of direct fabrication using the point-by-point FsLDW). The PDMS replicas showed good focusing and imaging performances. We anticipate that this method may serve as an enabler for the mass production of 3D artificial compound eyes and promote their practical applications in the near future.
关键词： Two-photon polymerization,Compound eyes,PDMS casting,Femtosecond laser
更新于2025-09-12 10:27:22
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Induced Circular Dichroism of Jet-Cooled Phenol Complexes with <i>R</i> -(–)-2-Butanol
摘要： The induced circular dichroism (ICD) of phenol complexed with R-(–)-2-butanol (PhOH-(–)BOH) in a supersonic jet is investigated using resonant two-photon ionization CD (R2PICD) spectroscopy. The R2PICD spectrum of PhOH-(–)BOH exhibits nonzero ICD bands near the absorption region of bare PhOH, where (–)BOH is transparent. Two different conformers containing a single hydrogen bond between PhOH and (–)BOH are identified using ultraviolet(UV)-UV hole-burning and infrared (IR) ion-dip spectroscopy combined with quantum theoretical calculations. The ICD values of the two conformers are similar to each other. To understand these similar ICD effects of the conformers, the geometrical asymmetry of the PhOH moiety bound to (–)BOH and the coupling strength of the electric transition dipole moments between PhOH and (–)BOH are estimated. Comparing the ICD values of PhOH-(–)BOH with those of PhOH-(–)-L-methyl lactate in the previous report (Hong, A.; Moon, C. J.; Jang, H.; Min, A.; Choi, M. Y.; Heo, J.; Kim, N. J. J. Phys. Chem. Lett. 2018, 9, 476-480), we investigate the physical properties that may govern the differences of the ICD values between the two complexes.
关键词： R-(–)-2-Butanol,Phenol Complexes,Supersonic Jet,Resonant Two-Photon Ionization CD Spectroscopy,Induced Circular Dichroism
更新于2025-09-12 10:27:22
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Dependence of the Two-Photon Absorption Coefficient of Steel on the Pulse Duration During Its Ablation by Femto- and Picosecond Laser Pulses
摘要： The dependences of the depth of single-pulse ablation of the steel surface on the energy density of ultrashort laser pulses (0.3–12 ps) with a wavelength of 515 nm have the form different from the usual logarithmic one for linear absorption of radiation. Since the density of states of free conduction electrons in the s band is low, and the d band of strongly bound electrons with a high density of states is located around the Fermi level, these dependences have been approximated within the two-photon absorption model. The two-photon absorption coefficient increases almost linearly with the duration of laser pulses, which indicates the saturation of absorption and allows estimating the corresponding parameters of the electronic subsystem.
关键词： picosecond,two-photon absorption,femtosecond,ultrashort laser pulses,steel ablation
更新于2025-09-12 10:27:22
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Distinct metabolic profiles in Drosophila sperm and somatic tissues revealed by two-photon NAD(P)H and FAD autofluorescence lifetime imaging
摘要： Metabolic profiles vary across all levels of biological diversity, from cells to taxa. Two-photon fluorescence lifetime imaging microscopy (FLIM) facilitates metabolic characterisation of biological specimens by assaying the intrinsic autofluorescence of the ubiquitous coenzymes NAD(P)H and FAD. the potential of this method for characterising the diversity of organismal metabolism remains largely untapped. Using FLIM in Drosophila melanogaster, we show tissue-specificity in fluorescence lifetime that reflects variation in redox patterns. In particular, sperm cells exhibited elevated glycolysis relative to other tissues. We also show that sperm metabolism is phenotypically plastic: compared to male-stored sperm, sperm stored in the female’s storage organ showed a substantial reduction in the protein-bound FAD lifetime fraction but no change in the NAD(P)H profile. This study represents the first ex vivo investigation of sperm metabolism using FLIM.
关键词： two-photon fluorescence lifetime imaging microscopy,FAD,Drosophila melanogaster,NAD(P)H,glycolysis,sperm metabolism,OxPHOS
更新于2025-09-12 10:27:22
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Comparison of Sensitive Volumes Associated with Ion-and Laser-Induced Charge Collection in an Epitaxial Silicon Diode
摘要： A sensitive volume is developed using pulsed laser-induced collected charge for two bias conditions in an epitaxial silicon diode. These sensitive volumes show good agreement with absorption laser-induced collected charge at a variety of focal positions and pulse energies. When compared to ion-induced collected charge, the laser-based sensitive volume over predicts the experimental collected charge at low bias and agrees at high bias. A sensitive volume based on ion-induced collected charge adequately describes the ion experimental results at both biases. Differences in the amount of potential modulation explain the differences between the ion- and laser-based sensitive volumes at the lower bias. Truncation of potential modulation by the highly doped substrate at the higher bias results in similar sensitive volumes.
关键词： single-event transients,two-photon absorption,sensitive volume,single-event effects,Pulsed laser
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Towards Optimized Photon-Pair Sources for Two-Photon Transitions
摘要： Two-photon absorption (TPA) is a nonlinear optical process with wide applications in ?uorescence microscopy and spectroscopy of organic molecules and compounds, as it enables atoms or molecules to transition into states that may otherwise be inaccessible by a single photon, either because of selection rules or energy conservation. Despite its common use, TPA is a rather inef?cient process, often requiring very large photon numbers to produce significant results. It has been demonstrated and analytically described [1,2], that using frequency entangled pairs of photons can in some cases enhance the ef?ciency of TPA. For this to occur, the joint spectral amplitude (JSA) of the photon-pair state, which describes the spectral entanglement between the pair, must be engineered according to the spectral properties of the TPA response-function of the speci?c system in question. In this work, we consider different cases for the spectral functionality of TPA and propose that the control of the group indices of the modes involved in the pair-generation process is a key property in the design of photon-pair sources for optimized TPA.
关键词： joint spectral amplitude,spectral entanglement,group indices,Two-photon absorption,photon-pair sources
更新于2025-09-11 14:15:04
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The Preparation and Up-Conversion Properties of Full Spectrum CsPbX3 (X = Cl, Br, I) Quantum Dots Glasses
摘要： All-inorganic perovskite (CsPbX3) quantum dots (QDs) have achieved unprecedented success in various applications due to their outstanding performance. Nevertheless, the inherent instability of these QDs severely limits their practical applications. Here, ultra-stable full visible spectrum CsPbX3 (X = Cl, Br, I) QDs glasses were prepared successfully. For the first time, CsPbX3 QDs glasses were observed full spectrum tunable up-conversion (UC) emission (420–711 nm) with the excitation of 800 nm femtosecond (fs) laser. Importantly, the two-photon absorption properties, the exciton binding energy and the UC full width at half maximum (FWHM) of the CsPbCl1.5Br1.5 (blue), CsPbBr3 (green), and CsPbBr1.5I1.5 (red) QDs glasses were studied in depth. Furthermore, CsPbCl1.5Br1.5 was observed to have the highest exciton binding energy (~87.5 meV), allowing the CsPbCl1.5Br1.5 QDs glass to act as a good optical gain material that could more easily achieve amplified spontaneous emission (ASE).
关键词： CsPbX3 perovskite,full spectrum,two-photon,QDs glass,UC emission
更新于2025-09-11 14:15:04
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Application of Two-Photon-Absorption Pulsed Laser for Single-Event-Effects Sensitivity Mapping Technology
摘要： Single-event effects (SEEs) in integrated circuits and devices can be studied by utilizing ultra-fast pulsed laser system through Two Photon Absorption process. This paper presents technical ways to characterize key factors for laser based SEEs mapping testing system: output power from laser source, spot size focused by objective lens, opening window of Pockels cell, and calibration of injected laser energy. The laser based SEEs mapping testing system can work in a stable and controllable status by applying these methods. Furthermore, a sensitivity map of a Static Random Access Memory (SRAM) cell with a 65 nm technique node was created through the established laser system. The sensitivity map of the SRAM cell was compared to a map generated by a commercial simulation tool (TFIT), and the two matched well. In addition, experiments in this paper also provided energy distribution pro?le along Z axis that is the direction of the pulsed laser injection and threshold energy for different SRAM structures.
关键词： pulsed laser,SRAM,single event effect,sensitive mapping,two photon absorption
更新于2025-09-11 14:15:04