共查询到20条相似文献,搜索用时 421 毫秒
1.
X. Lu Q. Yang C. Xiao A. Hirose 《Applied Physics A: Materials Science & Processing》2006,82(2):293-296
Diamond nanocone, graphitic nanocone, and mixed diamond and graphitic nanocone films have been synthesized through plasma
enhanced hot filament chemical vapor deposition (HFCVD). The field emission properties of these films have been experimentally
investigated. The studies have revealed that all three kinds of nanocone films have excellent field electron emission (FEE)
properties including low turn-on electric field and large emission current at low electric field. Compared with the diamond
nanocone films (emission current of 86 μA at 26 V/μm with the turn-on field of 10 V/μm), the graphitic nanocone films exhibit
higher FEE current of 1.8×102 μA at 13 V/μm and a lower turn-on filed of 4 V/μm. The mixed diamond and graphitic nanocone films have been found to posses
FEE properties similar to graphitic nanocone films (emission current of 1.7×102 μA at 20 V/μm with the turn-on field of 5 V/μm), but have much better FEE stability than the graphitic nanocone films.
PACS 81.07.Bc; 81.05.Uw; 79.70.+q 相似文献
2.
L. Cerdán A. Costela I. García-Moreno O. García R. Sastre 《Applied physics. B, Lasers and optics》2009,97(1):73-83
The characteristics of amplified spontaneous emission (ASE) from asymmetric planar waveguides and quasi-waveguides consisting
of thin films of poly(methyl methacrylate) incorporating lasing dye pyrromethene 597 deposited onto quartz and glass substrates,
respectively, are investigated. The variable stripe length and moving constant stripe methods, together with appropriate theoretical
expressions which take into account gain saturation and a simple model based on a four-level laser, allow for obtaining the
net gain coefficients as a function of pump intensity, losses, pump thresholds for the onset of ASE, effective stimulated
emission cross sections, pump saturation intensities, and saturation lengths. Net gain coefficients of up to 84±3 cm−1 at a pump intensity of 404 kW/cm2 (28 μJ/pulse) for quasi-waveguides and up to 59±6 cm−1 at a pump intensity of 360 kW/cm2 (25 μJ/pulse) for waveguides were obtained, with pump thresholds of 15.7 kW/cm2 (1.1 μJ/pulse) and 6.3 kW/cm2 (0.43 μJ/pulse), respectively. When waveguides 8 μm thick were irradiated with pulses of 200 kW/cm2 at 10 Hz repetition rate, the ASE remained at 79% of its initial value after 1000 pump pulses in the same position of the
sample. In quasi-waveguides 10 μm thick, the emission remained at 82% of the initial value under the same conditions. 相似文献
3.
S. M. Levshov I. V. Berezovskaya N. P. Efryushina S. I. Vdovenko I. P. Kovalevskaya V. P. Dotsenko 《Journal of Applied Spectroscopy》2012,79(1):70-75
Spectral-luminescent properties of Eu2+ ions in alkaline earth dilithiosilicates of composition MLi2SiO4 (M = Ca, Sr, Ba) have been studied at 77 K. The reasons for the different positions of the Eu2+ 4f 65 d → 4f 7 emission band maximum in spectra of MLi2SiO4 were found based on the obtained results. It was shown that the increase in the decay time of the Eu2+ emission on going from CaLi2SiO4 (0.41μs) through BaLi2SiO4 (0.64 μs) to Sr-silicate (1.11μs) correlates with the shift of the emission maximum to longer wavelengths. 相似文献
4.
Field emission in diamond and graphite-like polycrystalline films is investigated experimentally. It is shown that the emission
efficiency increases as the nondiamond carbon phase increases; for graphite-like films the threshold electric field is less
than 1.5 V/μm, and at 4 V/μm the emission current reaches 1 mA/cm2, while the density of emission centers exceeds 106 cm−2. A general mechanism explaining the phenomenon of electron field emission from materials containing graphite-like carbon
is proposed.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 1, 56–60 (10 July 1998) 相似文献
5.
Jong-Hyun Lee Parlindungan Yonathan Hyun-Tae Kim Dang-Hyok Yoon Jaemyung Kim 《Applied Physics A: Materials Science & Processing》2008,93(2):511-516
The field emission properties of multi-walled carbon nanotubes were examined using a screen-printed thick film with a diode-type
configuration in a vacuum. The effects of various concentrations of two different ceramic fillers, indium tin oxide (ITO)
powder and a glass frit, on the emission current density and turn-on field were evaluated. The emission properties of both
pastes were dependent on the amount of filler. Considerably enhanced emission properties were obtained with the paste containing
5–10 wt.% of either ITO or the glass frit compared with those without a filler. The paste containing the ceramic filler showed
enhanced emission properties compared with that containing the 5 wt.% Ag conventionally used, which confirmed the importance
of the filler. The paste containing 10 wt.% ITO represented an emission current density of 176.4 μA/cm2 at 5 V/μA, a turn-on field of 1.87 V/μA for an emission current density of 1 μA/cm2 and a field enhancement factor of 7580. The paste formulation was also found to be suitable for fine patterning using UV-lithography
techniques. A long-term stability test for 110 h of a paste containing 10 wt.% ITO revealed a half-life of approximately 30000 h,
which is appropriate for commercial applications. 相似文献
6.
Dattatray J. Late Ranjit V. Kashid Chandra Sekhar?Rout Mahendra A. More Dilip S. Joag 《Applied Physics A: Materials Science & Processing》2010,98(4):751-756
Field emission studies of WO2.72 nanowires synthesized by a solvothermal method have been performed in the planar diode configuration under ultra high vacuum
conditions. Fowler–Nordheim plots obtained from the current-voltage characteristics follow the quantum mechanical tunneling
process and a current density of ∼8.3×106 μA/cm2 can be drawn at an applied electric field of 2 V/μm. The field enhancement factor is 33025, while the turn-on field is only
1.4 V/μm. The emission current-time plot recorded at the pre-set value of emission current of 1 μA over a period of more than
3 h exhibits an initial increase and a subsequent stabilization of the emission current. The results reveal that the WO2.72 nanowire emitters synthesized by the solvothermal method are promising cathode materials for practical applications. 相似文献
7.
P. Zhang H. Qi X. Zhang Q. Zhao Y. Tian D. Yu 《Applied Physics A: Materials Science & Processing》2006,84(1-2):165-169
Novel lotiform ZnO nanostructures were synthesized on silicon substrate via simple thermal evaporation. The average diameter of the ZnO nanostructures is ∼1.5 μm. The lotiform-like ZnO structures were formed by nanorods arrays with the average diameter of 70 nm. The as-grown lotiform ZnO nanostructures have excellent field-emission properties such as the low turn-on field of 3.4 V/μm, and very high emission current density of 12.4 mA/cm2 at the field of 9.6 V/μm. These features make the lotiform-like ZnO nanostructures competitive candidates for field-emission-based displays. PACS 61.46.-w; 61.82.Rx; 78.67.-n; 73.63.Bd; 74.78.Na 相似文献
8.
J.F. Philipps T. Töpfer H. Ebendorff-Heidepriem D. Ehrt R. Sauerbrey 《Applied physics. B, Lasers and optics》2001,72(4):399-405
Er3+ emission and lasing properties at 1.5 μm were studied in fluoride phosphate glasses (FP20) with different doping concentrations
as well as in a commercial phosphate glass (Kigre QX). Emission decay behaviour at 1 μm and 1.5 μm was examined with respect
to energy transfer between ytterbium and erbium. Emission cross-sections were determined using the reciprocity and Füchtbauer–Ladenburg
methods. Gain spectra were calculated for the glasses and related to differences in the tuning curves and lasing properties.
The temperature rise due to the quantum defect was determined via the ratios of green upconversion luminescence for different
pump powers. The results from the laser and tuning experiments indicate that the FP20 glass offers good possibilities in broadband
amplification and the generation of ultrashort pulses.
Received: 24 August 2000 / Revised version: 27 October 2000 / Published online: 7 February 2001 相似文献
9.
Cuicui Wang Ke Yu Lijun Li Qiong Li Ziqiang Zhu 《Applied Physics A: Materials Science & Processing》2008,90(4):739-743
Two kinds of ZnO nanotubes, including taper-like and flat-roofed tubes, have been successfully fabricated using a simple aqueous
solution route by changing the experimental conditions. All the obtained nanotubes have a uniform size of 500 nm in diameter,
10–50 nm in wall thickness, and 2–5 μm in length. The growth mechanism of two kinds of ZnO nanotubes was investigated. Field
emission measurements showed that tapering nanotubes have the good field emission performance with a low turn-on field of
∼ 2.1 V μm-1 and a low threshold field of ∼ 3.8 V μm-1, which suggests the possible applications of the ZnO tubular structures in field emission microelectronic devices.
PACS 73.61.Ga; 73.63. Fg; 85.45.Db 相似文献
10.
R. R. Xu Y. Tian M. Wang L. L. Hu J. J. Zhang 《Applied physics. B, Lasers and optics》2011,102(1):109-116
A new type host of germanate glass (GeO2− BaO−BaF2−Ga2O3−La2O3) codoped with Tm2O3 has been investigated for application as laser material. It possesses a large emission cross section with the value of 9.3×10−21 cm2 at 1.8 μm. Judd-Ofelt intensity parameters and radiative transition probability are calculated and analyzed by Judd-Ofelt
theory and absorption spectra. The infrared emission spectra at 1.8 μm have been obtained by using a 794 nm laser diode as
excitation resource. The emission intensity ratio of 1.8 (3F4→3H6) to 1.47 μm (3H4→3F4) increases, while the experimental lifetime of the Tm3+:3H4 level decreases by increasing Tm2O3 concentration, which is attributed to the presence of a cross relaxation process. The most intensive emission at 1.8 μm is
achieved from the germanate glass with the concentration of Tm2O3 reaches 1.0 wt%. The extended overlap integral method is used to calculate the microparameter of the energy transfer and
the critical distance, which are derived to better understand the energy transfer process of thulium ions in the germanate
glass responsible for emission at 1.8 μm. 相似文献
11.
Zhuan Su Kangyu Chen Yuan Guo Haiping Qi Xiao-Feng Yang Minglei Zhao 《Journal of fluorescence》2010,20(4):851-856
A coumarin-based fluorescent chemosensor 1 for Zn2+ was designed and synthesized. Compound 1 exhibits lower background fluorescence due to intramolecular photoinduced electron transfer. However, upon mixing with Zn2+ in 30% (v/v) aqueous ethanol, a “turn-on” fluorescence emission is observed. The fluorescence emission increases linearly with Zn2+ concentration in the range 0.5–10 μmol L−1 with a detection limit of 0.29 μmol L−1. No remarkable emission enhancement was, however, observed for other metal ions. The proposed chemosensor was applied to
the determination of Zn2+ in water samples with satisfactory results. 相似文献
12.
《Applied physics. B, Lasers and optics》1981,24(1):33-38
We report infrared laser emission in the region of 3 to 5 μm from sodium vapour optically pumped by a pulsed dye laser with
wavelengths ranging from 585 to 610nm. Twophoton excitation processes are believed to be responsible for the primary excitation.
Both molecular transitions (4 to 5 μm) between high lying states, and atomic transitions (52
S
1/2−42
P
3/2,1/2 at 3.41 μm) have been identified. 相似文献
13.
Chen Hong-sheng Qi Jun-jie Zhang Yue Liao Qing-liang Huang Yun-hua 《Frontiers of Physics in China》2007,2(2):195-198
The direct growth of a tetrapod-like ZnO nanostructure has been accomplished by using a thermal oxidation method without any
catalysts. Studies on the field emission properties of the ordered ZnO nanotetrapods films found that the shape of the ZnO
nanotetrapods has considerable effect on their field emission properties, especially the turn-on field and the emission current
density. Compared with the rod-like legs ZnO nanotetrapods, the nanotetrapods with acicular legs have a lower turn-on field
of 2.7 V/μm at a current density of 10 μA/cm2, a high field enhancement factor of 1830, and an available stability. More importantly, the emission current density reached
1 mA/cm2 at a field of 4.8 V/μm without showing saturation. The results could be valuable for using the ZnO nanostructure as a cold-cathode
field-emission material.
相似文献
14.
We have studied the possibility to detect vector mesons via their decay into μ+μ− pairs in heavy-ion collisions at FAIR with a muon detection system as part of the Compressed Baryonic Matter (CBM) experiment.
The text was submitted by the authors in English. 相似文献
15.
R. B. Rakhi X. Lim X. Gao Y. Wang A. T. S. Wee K. Sethupathi S. Ramaprabhu C. H. Sow 《Applied Physics A: Materials Science & Processing》2010,98(1):195-202
The present work describes the field emission characteristics of nanoscale magnetic nanomaterial encapsulated multi-walled
carbon nanotubes (MWNTs) fabricated over flexible graphitized carbon cloth. Ni/MWNTs, NiFe/MWNTs and NiFeCo/MWNTs have been
synthesized by catalytic chemical vapor decomposition of methane over Mischmetal (Mm)-based AB3 (MmNi3, MmFe1.5Ni1.5 and MmFeCoNi) alloy hydride catalysts. Metal-encapsulated MWNTs exhibited superior field emission performance than pure MWNT-based
field emitters over the same substrate. The results indicate that a Ni-filled MWNT field emitter is a promising material for
practical field emission application with a lowest turn-on field of 0.6 V/μm and a high emission current density of 0.3 mA/cm2 at 0.9 V/μm. 相似文献
16.
Field emission from single-walled carbon nanotubes (SWNTs) aligned on a patterned gold surface is reported. The SWNT emitters
were prepared at room temperature by a self-assembly monolayer technique. SWNTs were cut into sub-micron lengths by sonication
in an acidic solution. Cut SWNTs were attached to the gold surface by the reaction between the thiol groups and the gold surface.
The field-emission measurements showed that the turn-on field was 4.8 V/μm at an emission current density of 10 μA/cm2. The current density was 0.5 mA/cm2 at 6.6 V/μm. This approach provides a novel route for fabricating CNT-based field-emission displays.
Received: 3 May 2002 / Accepted: 6 May 2002 / Published online: 4 December 2002
RID="*"
ID="*"Corresponding author. Fax: +82-54/279-8298, E-mail: ce20047@postech.ac.kr 相似文献
17.
Luminescent quantum dots (QDs)-semiconductor nanocrystals were promising alternative to organic dyes for fluorescence-based
applications. In this paper, we developed procedures to use mercaptoacetic acid (MAA) to modify ZnSe nanoparticles and made
the nanoparticles to be soluble for the quantitative and selective determination of bovine serum albumin (BSA). Maximum fluorescence
intensity was produced at pH 7.0, with excitation and emission wavelengths at 242 and 348 nm, respectively. Under optimal
conditions, the straight line equation: △
F = 0.38 + 0.34 C (μg/ml) was found between the relative fluorescence intensity and the concentration of BSA in the range of
9.6–124.8 μg/ml, and the limit of detection was 2 μg/ml. 相似文献
18.
Dattatray J. Late Vindhyesh R. Singh Sucharita Sinha Mahendra A. More K. Dasgupta Dilip S. Joag 《Applied Physics A: Materials Science & Processing》2009,97(4):905-909
Micro/nano structures have been obtained by laser surface treatment on sintered LaB6 pellets employing a picosecond pulsed Nd:YAG laser at a pressure of ∼1×10−3 mbar. The X-ray diffraction pattern of the laser treated pellet shows a set of well defined diffraction peaks, indexed to
the cubic phase of LaB6 only. The scanning electron microscope studies reveal formation of micro and nano structures upon laser treatment and the
resultant surface morphology is found to be strongly influenced by the laser fluence. Field electron emission studies made
on the LaB6 pellet, treated with optimized laser fluence, have been performed in a planar diode configuration under ultra high vacuum
conditions. The threshold field required to draw an emission current density of ∼10 μA/cm2 has been found to be ∼2.3 V/μm and a current density of ∼530 μA/cm2 has been drawn at an applied field of 5.2 V/μm. The Fowler-Nordheim plot is found to be linear in accordance with the quantum
mechanical tunneling phenomenon, confirming the metallic nature of the emitter. The emission current at the pre-set value
∼10 μA shows very good stability over a period of more than 3 hours. The present results emphasize the effectiveness of a
picosecond laser treatment towards fabrication of a nano metric LaB6 emitter for high current density applications. 相似文献
19.
We report on 2.0-μm emission characteristic and energy transfer of Ho3+-doped tellurite glass sensitized by Tm3+ upon excitation of a conventional 808 nm laser diode. The Judd-Ofelt strength parameters, spontaneous radiative transition
probabilities and radiative lifetime of Ho3+ have been calculated from the absorption spectra by using the Judd-Ofelt theory. Significant enhancement of 2.0-μm emission
of Ho3+ has been observed with increasing Tm3+ doping up to 0.7 mol%. The energy transfer coefficient of the forward Tm3+→Ho3+ is approximately 17 times larger than that of the backward Tm3+←Ho3+ energy transfer. Our result indicates that the maximum gain of 2.0-μm emission, assigned to the transition of 5I7→5I8 of Ho3+, might be achieved from the tellurite glass at the concentration of 0.5 mol% of Tm2O3 and 0.15 mol% of Ho2O3. The high gain coefficient and quantum efficiency (1.16) along with the large value of the product of the stimulated emission
cross-section and the measured radiative lifetime (4.12×10−27 m2s) of the Ho3+/Tm3+-codoped tellurite glasses might find potential applications in efficient 2.0-μm laser. 相似文献
20.
R. Orghici U. Willer M. Gierszewska S.R. Waldvogel W. Schade 《Applied physics. B, Lasers and optics》2008,90(2):355-360
A fiber optic approach for the determination of the carbon dioxide concentration in the gas or fluid phase during sequestration,
as well as for the sensing of the explosive TNT is described. The sensor consists of a quartz glass multimode fiber with core
diameter of 200 μm and is based on the evanescent field principle. Cladding and jacket of the fiber are removed in the sensing
portion, therefore interaction between light within the fiber and the surrounding medium is possible. A single-mode distributed
feedback (DFB) laser diode with an emission wavelength around λ= 1.57 μm and a frequency doubled passively Q-switched Cr4+:Nd3+:YAG microchip laser (λ= 1064 nm)are used as light sources. The experimental setup and the sensitivity of the evanescent field
sensor are characterized.
PACS 42.62.Fi; 42.79.Wc; 07.07.Df 相似文献