排序方式: 共有285条查询结果,搜索用时 15 毫秒
71.
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
72.
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
73.
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
74.
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
75.
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
76.
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
77.
We investigate the plasmon resonances for silver nanowires with a non-regular cross section. To study the relationship between
the cross section and the spectrum of the plasmon resonances, we consider cross sections evolving from a rectangular shape
to a triangular one. In particular, we study the influence of the sharpness of a corner on the near-field enhancement at the
vicinity of a particle and discuss its implications for surface-enhanced Raman scattering. We also investigate the influence
of the absorption on the plasmon-resonance spectrum and on the near-field enhancement.
Received: 15 August 2001 / Published online: 10 October 2001 相似文献
78.
E.G. Gamaly A.V. Rode A. Perrone A. Zocco 《Applied Physics A: Materials Science & Processing》2001,73(2):143-149
We present two sets of experimental results on the ablation-rate decrease with increase of the number of consecutive laser
pulses hitting the same spot on the target surface. We have studied laser ablation of a carbon target with nanosecond pulses
in two different interaction regimes: one with a XeCl laser (λ=308 nm) and the other with a Nd:YAG laser (λ=1064 nm), in both
cases at the intensity ∼5×108 W/cm2 Two different mechanisms were found to be responsible for the ablation-rate decrease; they are directly related to the two
different laser–matter interaction regimes. The UV-laser interaction is in the regime of transparent vapour (surface absorption).
The increase of the neutral vapour density in the crater produced by the preceding laser pulses is the main reason for the
decrease of ablation rate. With the IR laser each single laser pulse interacts with a partially ionised plume. With increase
of the number of pulses hitting the same spot on the target surface, the laser–matter interaction regime gradually changes
from the near-surface absorption to the volume absorption, resulting in the decrease in absorption in the target and thus
in the decrease in the ablation rate. The change in the evaporation rate was considered for both vacuum and reactive-gas environments.
Received: 21 February 2001 / Accepted: 26 February 2001 / Published online: 23 May 2001 相似文献
79.
In order to understand the physical mechanism, time-resolved dynamics of 355 nm nanosecond laser induced entrance and exit surface damage on fused silica was investigated by using shadow graphic technique. The results show that the damage mechanism is different between the entrance and exit surface during nanosecond laser interaction with fused silica. The plasma and shock waves in air is relatively higher at the entrance surface. The entrance surface damage is reduced because plasma shielding limits energy deposition. Without plasma shielding, the exit surface damage is more serious for more laser energy deposition in material. And without the stress of plasma and shock waves, the material is ejected easily at rear surface. These are confirmed by damage micrograph at the entrance and exit surface. 相似文献
80.
Ultrashort pulsed laser ablation in vacuum of different targets was performed in order to investigate the possibility of producing nanoparticles with controlled size and shape. A systematic morphology characterization of deposited products was performed for nickel and silicon as a function of laser pulse intensity and wavelength, at a fixed pulse repetition rate. The nanoparticles were investigated by atomic force microscopy, and clear trends for their size and shape anisotropy were evidenced. The best conditions to obtain nanosized particles of oblate ellipsoidal shape, with the minor axis below 10 nm, were determined in the case of nickel targets. Our results show that ultrashort pulse laser deposition can be considered as an interesting technique for the tailoring of nanogranular films with the desired particles dimension and shape, according to the peculiar properties required in specific applications. Moreover, the preliminary features are very promising from the point of view of the production of magnetoresistive films with specific anisotropy. 相似文献