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Dynamics of interatomic Coulombic decay in neon dimers by XUV-pump–XUV-probe spectroscopy
摘要： We apply the Monte Carlo wave-packet approach to study the interatomic Coulombic decay (ICD) dynamics of neon dimers after removing a 2s electron from one of the Ne atoms by one-photon absorption from an XUV pulse. This method reproduces well both the lifetime for the 2s inner-valence vacancy in Ne2+(2s?1) and the kinetic energy release (KER) spectra for the coincident Ne+ and Ne2+ fragments following triple ionization, i.e., two photoionizations and one ionization via ICD, of Ne2 measured in an XUV-pump–XUV-probe experiment [K. Schnorr et al., Phys. Rev. Lett. 111, 093402 (2013)]. Comparisons between the calculated and measured nuclear KER spectra give physical insights in the considered process. For example, an analysis of the ratios between the low- and high-energy peaks in the nuclear KER spectra for large delays provides an estimate of the photoionization cross sections for removing a 2p electron from the excited states in Ne2+(2s?1). Such comparisons also allow an estimate for the ICD rates for the 2s inner-valence vacancy in the single-site two-hole state in Ne2+(2s?12p?1). Finally, the influence of photon statistics of the free electron laser pulses on the nuclear KER spectra is considered.
关键词： neon dimers,interatomic Coulombic decay,kinetic energy release spectra,XUV-pump–XUV-probe spectroscopy,Monte Carlo wave-packet approach
更新于2025-09-23 15:23:52
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Efficient three-dimensional atom localization using probe absorption in a diamond-configuration atomic system
摘要： A new scheme for three-dimensional (3D) atom localization is proposed based on measuring the probe absorption spectra in a four-level diamond-configuration atomic system, in which the atom interacts with three orthogonal standing-wave laser fields. Due to spatial-dependent interaction between atom and fields, position information of the atom can be obtained by measuring the absorption spectra of the weak probe field. The results show that atom localization properties can be significantly improved and some interesting spatial localization structures such as double-layer lantern-like, single-layer lantern-like, gourd-like, cylinder-like, and ellipsoid-like patterns can be achieved when we adjust system parameters properly. Most importantly, we can find the atom at a particular position in 3D space with 100% probability under appropriate conditions.
关键词： probe absorption,3D atom localization,standing wave
更新于2025-09-23 15:22:29
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In Situ Quantification of the Young’s Modulus of Nuclei In Multiple Cellular States Using A Modified Fiber Probe Sensor
摘要： In this work, a modified fiber probe sensor (MFP sensor) with a considerable length-diameter ratio tip was developed to quantitatively characterize the Young’s modulus of the cell nucleus in multiple cellular states. The MFP sensor has a needle tip with an extended length of 30 μm and a diameter of 150 nm. The length of the tip exceeds the diameter of most cells, so that it can penetrate the cell membrane with minimal damage and reach the nucleus. This allows the measurement of the Young’s modulus of intact cell nuclei under different cellular states without the phenomenon that the cantilever contacts the cell membrane. Moreover, the stiffness of the MFP sensor is reduced by a factor of 25 to better match that of the cell membrane and nucleus, which enables high-precision mechanical measurements. The MFP sensor was successfully used to quantify the Young’s modulus of the intact cell nuclei in the non-adherent, adherent and early apoptotic states. Experimental results validated the capability and versatility of the developed method.
关键词： In Situ,Modified Fiber Probe Sensor,Young’s Modulus,Cell Nucleus,Atomic Force Microscopy
更新于2025-09-23 15:22:29
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Electrical characterization of single nanometer-wide Si fins in dense arrays
摘要： This paper demonstrates the development of a methodology using the micro four-point probe (μ4PP) technique to electrically characterize single nanometer-wide fins arranged in dense arrays. We show that through the concept of carefully controlling the electrical contact formation process, the electrical measurement can be confined to one individual fin although the used measurement electrodes physically contact more than one fin. We demonstrate that we can precisely measure the resistance of individual ca. 20 nm wide fins and that we can correlate the measured variations in fin resistance with variations in their nanometric width. Due to the demonstrated high precision of the technique, this opens the prospect for the use of μ4PP in electrical critical dimension metrology.
关键词： micro four-point probe,electrical characterization,finFET,sheet resistance,critical dimension metrology
更新于2025-09-23 15:22:29
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Spectroscopic Studies of Magnetron Sputtering Plasma Discharge in Cu/O2/Ar Mixture for Copper Oxide Thin Film Fabrication
摘要： Magnetron sputtering plasma for the deposition of copper oxide thin film has been investigated using optical emission spectroscopy and Langmuir probe. The intensity of the light emission from atoms and radicals in the plasma were measured using optical emission spectroscopy (OES). Then, Langmuir probe was employed to estimate the plasma density, electron temperature and ion flux. In present studies, reactive copper sputtering plasmas were produced at different oxygen flow rate of 0, 4, 8 and 16 sccm. The size of copper target was 3 inches. The dissipation rf power, Ar flow rate and working pressure were fixed at 400 W, 50 sccm and 22.5 mTorr, respectively. Since the substrate bias plays an important role to the thin film formation, the substrate bias voltages of 0, -40, -60 and -100 V were studied. Based on OES results, oxygen emission increased drastically when the oxygen flow rate above 8 sccm. On the other hand, copper and argon emission decreased gradually. In addition, Langmuir probe results showed a different ion flux when substrate bias voltage was applied. Based on these plasma diagnostic results, it has been concluded that the optimized parameter to produce copper oxide thin film are between -40 to -60 V of substrate bias voltage and between 8 to 12 sccm of oxygen flow rate.
关键词： optical emission spectroscopy,Langmuir probe,thin film,magnetron sputtering,Copper oxide
更新于2025-09-23 15:22:29
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Carrier-Induced Coherent Phonon Softening in Bismuth
摘要： With performing time-resolved pump-probe experiments with ultrashort pulses from a mode-locked Ti:sapphire laser, we report on the carrier-induced softening and dephasing of coherent phonon oscillations in the bismuth crystal. As the lattice displacement becomes severe at high pump power, a frequency shift can occur due to the lattice anharmonicity term. We clari?ed from the measurements done by varying the pulse duration that the phonon softening at high pump intensity in bismuth originates from the electron-interaction of photoexcited carriers not from the phonon anharmonicity. We also ?nd that the coherent phonon dephasing is accelerated at high carrier densities.
关键词： Pump-probe,Coherent phonon,Phonon softening
更新于2025-09-23 15:22:29
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A Sensitive Near-Infrared Fluorescent Probe for Detecting Heavy Metal Ag+ in Water Samples
摘要： Silver is a common catalyst in industrial production, and the frequent use of Ag+ can cause water pollution. Thus, the detection of Ag+ in the environment is necessary to determine the level of pollution from silver. In this work, we designed a new, highly selective near-infrared (NIR) fluorescent probe QCy to detect Ag+. The probe exhibits 'turn-off' fluorescence quenching responses at 760 nm towards Ag+ over other relevant cations, with outstanding sensitivity and a low detection limit (0.03 μM), which is considerably lower than the standard of the World Health Organization (WHO) for drinking water (0.9 μM). Meanwhile, QCy showed a very good linearity at a low concentration of Ag+ with a 'naked eye' visible color change of solution from blue to red. The probe has been applied successfully for the detection of Ag+ in real water samples.
关键词： selectivity,fluorescence probe,Ag+,sensitivity,water samples
更新于2025-09-23 15:22:29
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Numerical analysis of single-point spectroscopy curves used in photo-carrier dynamics measurements by Kelvin probe force microscopy under frequency-modulated excitation
摘要： In recent years, the investigation of the complex interplay between the nanostructure and photo-transport mechanisms has become of crucial importance for the development of many emerging photovoltaic technologies. In this context, Kelvin probe force microscopy under frequency-modulated excitation has emerged as a useful technique for probing photo-carrier dynamics and gaining access to carrier lifetime at the nanoscale in a wide range of photovoltaic materials. However, some aspects about the data interpretation of techniques based on this approach are still the subject of debate, for example, the plausible presence of capacitance artifacts. Special attention shall also be given to the mathematical model used in the data-fitting process as it constitutes a determining aspect in the calculation of time constants. Here, we propose and demonstrate an automatic numerical simulation routine that enables to predict the behavior of spectroscopy curves of the average surface photovoltage as a function of a frequency-modulated excitation source in photovoltaic materials, enabling to compare simulations and experimental results. We describe the general aspects of this simulation routine and we compare it against experimental results previously obtained using single-point Kelvin probe force microscopy under frequency-modulated excitation over a silicon nanocrystal solar cell, as well as against results obtained by intensity-modulated scanning Kelvin probe microscopy over a polymer/fullerene bulk heterojunction device. Moreover, we show how this simulation routine can complement experimental results as additional information about the photo-carrier dynamics of the sample can be gained via the numerical analysis.
关键词： Kelvin probe force microscopy,nanostructured photovoltaics,numerical simulations,photo-carrier dynamics,carrier dynamics,carrier recombination,carrier lifetime
更新于2025-09-23 15:22:29
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Three-Dimensional Scanning Hall Probe Microscopy for Final Stage of Crack Growth of Chromium Molybdenum Steel SCM440
摘要： Crack propagation around the stress concentration area causes fatigue failure. Non-destructive method is necessary for monitoring structure fatigue before destruction. We focused on a magnetic non-destructive evaluation method for crack growth. In order to understand the relation between crack propagation and changes in magnetic flux density, we observed the position of the positive and negative magnetic flux density distributions around the crack of tool steel (SCM440) plate using a scanning Hall probe microscope (SHPM). We found that the vertical component of the three-dimensional magnetic flux density moved as the crack growth. Furthermore, the magnetic component which is parallel to the tensile stress appeared just before destruction of the specimen.
关键词： Crack propagation,Scanning Hall probe microscope,Magnetic flux density
更新于2025-09-23 15:22:29
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Raman spectroscopy and its use for live cell and tissue analysis
摘要： As research progresses in the field of life sciences, there is an increased demand for new technologies that can allow us to study intact cells and tissues. The quantitative analysis and mathematical modeling of living things based on empirical data is useful for connecting molecular biology to new areas, such as computational biology. Raman spectroscopy is regarded as one of the possible methods by which we can observe living organisms in a noninvasive manner. This could improve the quality of research in the field of medicine and health and will largely contribute to society in the future. The present review introduces some techniques based on Raman spectroscopy and evaluates their applications in intact live samples.
关键词： Raman probe,Raman spectroscopy,Biomedical,in vivo
更新于2025-09-23 15:22:29