排序方式: 共有285条查询结果,搜索用时 140 毫秒
61.
I Bar-JosephH Shtrikman 《Solid State Communications》2003,127(12):765-770
We study the photoluminescence (PL) spectrum of a two-dimensional electron system at the high magnetic field limit, where all electrons reside at the lowest Landau level (ν<2). Using a gated structure we tune the electron density from the dilute limit to a dense electron gas, and follow the changes in the emission spectrum. We find that the spectrum at the dilute limit consists of two bound triplets, whose behavior is consistent with that of the dark and bright triplets. We show that the spectrum undergoes critical changes at ν=1/3, from an isolated charged exciton-like spectrum at ν<1/3, to a spectrum that reflects the interactions with the surrounding electrons above this filling factor. This behavior is found to be robust, independent of the electron density and magnetic field. We compare our observations with other recent low temperature PL measurements of a two-dimensional electron gas at high magnetic field and find good agreement and consistency. 相似文献
62.
Within the framework of the electromagnetic theory, the collective modes in the superlattice system composed of superionic conductors and ionic crystals are studied. The superionic conductor is described by the hydrodynamical model in which the anion cage is immersed in the cation liquid. The behavior of the modes are analysed in terms of the coupling strength between excitations pertaining to different layers. The coupling strength is controlled by varying the slab thicknesses. An interesting behavior in which the diffusion mode transforms to the relaxation mode when the coupling strength is varied from strong to weak is obtained. Also, the effect of the coupling strength on the acoustical and optical modes are shown. 相似文献
63.
We present finite difference time domain simulations of the enhancement of the optical transmission through a single subwavelength slit in a thick metal film caused by resonances of the electromagnetic fields in and near the slit. These can be enhanced by including a periodic modulation on the in-coupling surface, and the dependence of the transmission on the grating structural parameters is analysed in detail. 相似文献
64.
Masafumi Kashii Yoichiroh Hosokawa Hiroshi Kitano Yusuke Mori Kazufumi Takano Hiroyoshi Matsumura Tsuyoshi Inoue Satoshi Murakami Kazuomi Sugamoto Takatomo Sasaki Hiroshi Masuhara 《Applied Surface Science》2007,253(15):6447-6450
For precise X-ray diffraction (XRD) measurement giving the three-dimensional structure of proteins, it is important to prepare high-quality single crystals with suitable shape. As a new processing technique to obtain such protein crystals, we employed femtosecond laser-induced cleaving of protein crystal in a growth vessel containing water solution. An intact protein crystal was precisely processed without mechanical contact in its sealed growth vessel by focusing femtosecond laser pulses. We confirmed that three-dimensional processing of the crystal in its supersaturated solution was realized using multiphoton absorption and that the processing was efficiently enhanced by the cleaving behavior attributed to a photomechanical mechanism of the femtosecond laser ablation. 相似文献
65.
J.M. Pereira Jr. R.N. Costa Filho V.N. Freire G.A. Farias 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,3(1):119-123
The resonance properties of localized electrostatic surface modes associated with a finite number of ridges on an otherwise
planar surface are investigated. Numerical solutions of the homogeneous integral equations that describe the electromagnetic
fields in the vicinity of the ridges are used to obtain the dispersion relation of surface plasmons. The frequencies of the
electrostatic surface shape resonances are calculated for ridges with Gaussian, Lorentzian, sinusoidal, exponential, and triangular
profiles. We show the existence of splittings of the plasmon frequencies, which depends on the surface profile function and
on the distance between the ridges. Considering the ridge with a sinusoidal profile, we obtain the limit on the number of
ridges which generates a frequency splitting of the electrostatic surface shape resonances, whose frequency values converge
to those of the dispersion relation of surface plasmons on one-dimensional sinusoidal grating.
Received: 24 June 1997 / Received in final form: 5 September 1997 / Accepted: 15 September 1997 相似文献
66.
Aiko Narazaki Tadatake Sato Ryozo Kurosaki Yoshizo Kawaguchi Hiroyuki Niino 《Applied Surface Science》2009,255(24):9703-9706
Fabrication of FeSi2 nano- and microdot array was performed by utilizing droplet ejection through laser-induced forward transfer, which we named laser-induced dot transfer (LIDT). An amorphous FeSi2 alloy source film on a transparent support was illuminated from the support by a nanosecond excimer laser pulse patterned into migcrogrid form, resulting in size- and site-controlled dot deposition. Micro-Raman spectroscopy confirmed β-FeSi2 semiconducting crystalline phase even on unheated substrates. Moreover, the microdots exhibited near-infrared photoluminescence at the peak wavelength of 1.57 μm, which comes from the β-FeSi2 crystalline phase precipitated during the LIDT process. The dot size was successfully reduced to approximately 500 and 300 nm in diameter and height, respectively. This technique is useful for integrating functional nano- and microdots under atmospheric room-temperature conditions. 相似文献
67.
Ryohei Yasukuni Jean-Alexis Spitz Rachel Meallet-Renault Takuji Tada Tsuyoshi Asahi Yuji Hiraki Hiroshi Masuhara 《Applied Surface Science》2007,253(15):6416-6419
Three-dimensional dissection of a single actin stress fiber in a living cell was performed based on multi-photon absorption of a focused femtosecond laser pulse. The realignment process of an actin stress fiber was investigated after its direct cutting by a single-shot femtosecond laser pulse irradiation by high-speed transmission and fluorescence imaging methods. It was confirmed that mechanical force led by the femtosecond laser cutting propagates to entire cell through the cytockelton in a 100 μs time scale. The cut actin stress fiber was realigned in the time scale of a few tens of minutes. The dynamic analysis of the realignment induced by single-shot femtosecond laser gives new information on cell activity. 相似文献
68.
ZnO nanowires were fabricated on Au coated (0 0 0 1) sapphire substrates by using a pulsed Nd:YAG laser with a ZnO target in furnace. ZnO nanowires have various sizes and shapes with a different substrate position inside a furnace. The length and the diameter of these ZnO nanowires were around 3-4 μm and 120-200 nm, respectively, confirmed by scanning electron microscopy (SEM). The diameter control of the nanowires was achieved by varying the position of substrates. The ultraviolet emission of nanowires from the near band-edge emission (NBE) was observed at room temperature. The formation mechanism and the effect of different position of substrates on the structural and optical properties of ZnO nanowires are discussed. 相似文献
69.
Yongxue He Peng He Soack Dae Yoon P.V. Parimi F.J. Rachford V.G. Harris C. Vittoria 《Journal of magnetism and magnetic materials》2007
A magnetic field tunable, broadband, low-loss, negative refractive index metamaterial is fabricated using yttrium iron garnet (YIG) and a periodic array of copper wires. The tunability is demonstrated from 18 to 23 GHz under an applied magnetic field with a figure of merit of 4.2 GHz/kOe. The tuning bandwidth is measured to be 5 GHz compared to 0.9 GHz for fixed field. We measure a minimum insertion loss of 4 dB (or 5.7 dB/cm) at 22.3 GHz. The measured negative refractive index bandwidth is 0.9 GHz compared to 0.5 GHz calculated by the transfer function matrix theory and 1 GHz calculated by finite element simulation. 相似文献
70.
KENZO Yamaguchi TOMOHIRO Inoue MASAMITSU Fujii MASANOBU Haraguchi TOSHIHIRO Okamoto MASUO Fukui SHU Seki SEIICHI Tagawa 《中国物理快报》2007,24(10):2934-2937
Using numerical calculation, we examine the effects of gap distance of a pair of nano gap silver prisms with rounded corners on the local light intensity enhancement. Two peaks due to localized surface plasmon (LSP) excitation are observed in a wavelength range from 900nm to 300nm. The results demonstrate that peaks at a longer and a shorter wavelength corresponded to dipole-like and quadrupole-like LSP resonances, respectively. It is found that a gap distance up to 20 nm provides larger light intensity enhancement than that of a single silver nano prism with rounded corners. Furthermore, nano gap silver prisms are fabricated by direct focused ion beam processing, and we measure the scattering light spectrum of a pair of nano prisms by a confocal optical system. However, the two LSP peaks are not observed in visible range because the sizes of the nano gap and prisms are too large. 相似文献