共查询到20条相似文献,搜索用时 0 毫秒
1.
Kyung Min Byun Shuler M.L. Sung June Kim Soon Joon Yoon Donghyun Kim 《Lightwave Technology, Journal of》2008,26(11):1472-1478
A nanowire-mediated surface plasmon resonance (SPR) imaging is numerically investigated for enhanced sensitivity. The results calculated by rigorous coupled-wave analysis present that interplays between localized surface plasmons and surface plasmon polaritons contribute to sensitivity enhancement. Compared to conventional thin film-based SPR imaging measurement, an optimal nanowire structure can provide sensitivity enhancement by 3.44 times as well as highly linear detection property for quantification of surface reactions of interests. This paper demonstrates the potential and limitation for a highly sensitive, label-free, and real-time SPR imaging sensor based on periodic metallic nanowires. 相似文献
2.
3.
Strong Photoacoustic Signal Enhancement by Coating Gold Nanoparticles with Melanin for Biomedical Imaging 下载免费PDF全文
Tatjana Repenko Anne Rix Alexander Nedilko Jonas Rose Alina Hermann Rostislav Vinokur Sheila Moli Roberto Cao‐Milàn Martin Mayer Gero von Plessen Andreas Fery Laura De Laporte Wiltrud Lederle Dmitry N. Chigrin Alexander J. C. Kuehne 《Advanced functional materials》2018,28(7)
Photoacoustics is a powerful biomedical imaging and detection technique, because it is a noninvasive, nonionizing, and low‐cost method facilitating deep tissue penetration. However, suitable contrast agents need to be developed to increase the contrast for in vivo imaging. Gold nanoparticles are often discussed as potential sonophores due to their large absorption cross‐section and their tunable plasmon resonance. However, disadvantages such as toxicity and low photoacoustic efficiency in the tissue transparency window prevail, preventing their clinical application. As a result, there remains a strong need to develop colloidal photoacoustic contrast agents which absorb in the tissue transparency window, exhibit high photoacoustic signal, and are biocompatible. Here, a facile synthetic approach is presented to produce melanin shells around various gold nanoparticle geometries, from spheres to stars and rods. These hybrid particles show excellent dispersability, better biocompatibility, and augmented photoacoustic responses over the pure melanin or pristine gold particles, with a rod‐shape geometry leading to the highest performance. These experimental results are corroborated using numerical calculations and explain the improved photoacoustic performance with a thermal confinement effect. The applicability of melanin coated gold nanorods as gastrointestinal imaging probes in mouse intestine is showcased. 相似文献
4.
李立珺 《固体电子学研究与进展》2013,33(4)
通过热蒸发沉积法在常压、900°C高温条件下,合成了氧化锡纳米线结构。利用扫描电子显微镜、透射电子显微镜及选区电子衍射对样品的表面形貌和微结构进行了表征,X射线衍射、傅里叶变换红外光谱进一步证明所制纳米结构为金红石型氧化锡单晶结构。在77K和300K温度条件下,研究了所制氧化锡纳米线及其在氧气气氛中退火后的光致发光性能。 相似文献
5.
ZHUANG Hui-zhao LI Bao-li XUE Cheng-shan ZHANG Shi-ying WANG De-xiao SHEN Jia-bing 《半导体光子学与技术》2008,14(1):42-47
Large-scale GaN nanowires are successfully synthesized by ammoniating Ga2O3 films on Nb layer deposited on Si(111) substrates at 850 ℃. X-ray diffraction (XRD), scanning electron microscopy (SEM), field-emssion transmission electron microscope(FETEM), Fourier transformed infrared spectrum(FTIR) are used to characterize the structural and morphological properties of the as-synthesized GaN nanowires. The results reveal that the nanowires are pure hexagonal GaN wurtzite structure with a length of about several microns and a diameter between 50 nm and 100 nm. Finally, discussed briefly is the formation mechanism of gallium nitride nanowires. 相似文献
6.
7.
8.
氧化锌(ZnO)是直接宽带隙半导体材料,有高达60meV的激子束缚能,是下一代短波长光电材料的潜在材料。首先制备了优良的多孔氧化铝(Anodic Aluminum Oxide)有序孔洞阵列;以其为模板,采用直流电化学沉积的方法,在其规则排列的孔中沉积得到锌的纳米线;然后将其在高温下氧化,得到氧化锌的纳米线。XRD图显示Li掺杂前后的ZnO纳米线具有较好的晶态结构。对Li掺杂前后的ZnO纳米线进行光学特性测量,结果表明,ZnO纳米线有两个发光峰,分别位于382nm和508nm处;Li掺杂较大地改善了ZnO纳米线的发光性能,本征发光峰移到395nm处,蓝绿发光强度也有了很大程度的提高。 相似文献
9.
M. S. Ramanachalam A. Rohatgi W. B. Carter J. P. Schaffer T. K. Gupta 《Journal of Electronic Materials》1995,24(4):413-419
Photoluminescence (PL) measurements were carried out on commercial ZnO varistor samples that were electrically stressed and/or
annealed at different temperatures. Changes in the intensity of green and yellow luminescence centers were studied as a function
of annealing treatment. It was found that the ZnO luminescence (green and yellow) decrease with increase in annealing temperature,
reach a minimum at 700°C, and increase again beyond 800°C. Furthermore, these green and yellow luminescence bands observed
in the PL spectra are quenched in the ZnO varistor samples, compared to pure ZnO. In an electrically stressed ZnO varistor
sample, the luminescence intensity was found to be higher compared to the as-sintered varistor sample. Annealing of the stressed
varistor sample resulted in a decrease of the luminescence intensity. These PL observations are consistent with previous deep
level transient spectroscopy and doppler positron annihilation spectroscopy results. All of the experimental results are consistent
with the ion migration model of degradation and can be explained using a grain boundary defect model. 相似文献
10.
11.
12.
13.
14.
《固体电子学研究与进展》2014,(3)
在1 050°C条件下,利用碳热蒸发的方法在NiO覆盖的Si(100)衬底上制备了回力标形状的ZnO纳米棒,这是一种新的ZnO的纳米结构。通过结构分析,发现这种回力标形状的ZnO纳米棒具有纤锌矿结构。室温的光致发光图谱中有两个发光峰:380nm附近的弱近紫外发光峰和524nm及575nm附近较宽的绿光发光峰。拉曼谱以及X电子能量谱也用于研究其性质。最后讨论了缓冲层的作用及ZnO纳米棒的生长机理。 相似文献
15.
自催化方式制备ZnO纳米线及光致发光特性 总被引:1,自引:0,他引:1
采用化学气相沉积法,不用催化剂,在Si(111)基片上制备了ZnO纳米线。扫描电子显微镜(SEM)表征发现ZnO纳米线的直径在100nm左右。X射线衍射(XRD)图谱上只存在ZnO的(002)衍射峰。室温下光致发光谱(PL)中出现了389nm和357nm的紫外峰以及五个蓝光峰(450,468,474,481和491nm)。389nm峰为自由激子复合发射357nm峰是在LO声子的参与下,自由载流子碰撞形成自由激子过程的发光行为;468nm峰系电子从氧空位形成的浅施主能级向价带跃迁发光;450nm峰系电子从导带向锌空位形成的浅受主能级跃迁发光;474,481和491nm峰是声子伴线。 相似文献
16.
The ultraviolet (UV) photoelectric characteristics of transitional metal (Cu) doped ZnO nanowires produced by the self-catalytic
vapor–liquid–solid (VLS) method were investigated by performing a series of photoconduction and time-resolved measurements.
The photocurrent voltage characteristics obtained on the nanowires configured as two-terminal metal–semiconductor–metal photodetectors
exhibited a nonmonotonic behavior attributed to the interplay of several limiting mechanisms: Schottky contacts and trapping/detrapping
effects that take place at low and intermediate (pre-avalanche) bias regimes, respectively. In the intermediate biases, the
photocurrent was power-law dependent, i.e., changed with voltage as
and for excitation wavelengths of 365 nm, 302 nm, and 254 nm, respectively. The dependence of the exponent on the wavelength
of the light is analyzed and explained based on the detailed consideration of the contribution of different deep-defect Cu
levels formed within the band gap of ZnO. The study will be important to those working in the area of ZnO-based nanophotodetectors,
optical switches, and sensors. 相似文献
17.
Xuanhua Li Wallace Chik Ho Choy Haifei Lu Wei E. I. Sha Aaron Ho Pui Ho 《Advanced functional materials》2013,23(21):2728-2735
It is been widely reported that plasmonic effects in metallic nanomaterials can enhance light trapping in organix solar cells (OSCs). However, typical nanoparticles (NP) of high quality (i.e., mono‐dispersive) only possess a single resonant absorption peak, which inevitably limits the power conversion efficiency (PCE) enhancement to a narrow spectral range. Broadband plasmonic absorption is obviously highly desirable. In this paper, a combination of Ag nanomaterials of different shapes, including nanoparticles and nanoprisms, is proposed for this purpose. The nanomaterials are synthesized using a simple wet chemical method. Theoretical and experimental studies show that the origin of the observed PCE enhancement is the simultaneous excitation of many plasmonic low‐ and high‐order resonances modes, which are material‐, shape‐, size‐, and polarization‐dependent. Particularly for the Ag nanoprisms studied here, the high‐order resonances result in higher contribution than low‐order resonances to the absorption enhancement of OSCs through an improved overlap with the active material absorption spectrum. With the incorporation of the mixed nanomaterials into the active layer, a wide‐band absorption improvement is demonstrated and the short‐circuit photocurrent density (Jsc) improves by 17.91%. Finally, PCE is enhanced by 19.44% as compared to pre‐optimized control OSCs. These results suggest a new approach to achieve higher overall enhancement through improving broadband absorption. 相似文献
18.
19.
通过固相反应法制备了ZnO:Dy3 纳米粉末,样品的X射线衍射、透射电镜和选区电子衍射证实了ZnO:Dy3 纳米粉末属于六方纤锌矿多晶结构.研究了光致发光谱与激发波长和掺杂离子浓度的依赖关系.结果表明,从ZnO:Dy3 纳米粉末的光致发光光谱中首次发现除了Dy3 的4f→4f跃迁外,出现了Dy掺入ZnO后产生的两个缺陷A和B的宽谱带发射峰,峰值分别在600和760nm,半高宽分别约为200和100nm.在ZnO的激子激发下(385nm),峰值760nm的发光强度远远大于峰值在600nm的发光强度.样品的发射光谱中峰值的相对强度变化依赖于激发波长和Dy3 的掺杂浓度.当在Dy3 4f→4f激发下(454nm),光谱中只有Dy3 的4f态间的特征发射,而缺陷A,B不发光. 相似文献
20.
Cu掺杂ZnO薄膜的结构及发光特性 总被引:1,自引:0,他引:1
采用溶胶-凝胶旋涂法在玻璃衬底上制备了不同Cu掺杂量的ZnO薄膜。用显微镜和X射线衍射(XRD)研究了Cu掺杂对ZnO薄膜形貌和微结构的影响。结果表明,制备得到的ZnO薄膜具有应变小和c轴择优取向。室温下测量了样品Zn1-xCuxO的光致发光(PL)谱,发现所有样品的PL谱中均观察到435nm左右的蓝光发光带,发光带强度与Cu的掺杂量有关;当x=0.06时,Zn1-xCuxO薄膜的PL谱中出现了较强的蓝光发射。分析了掺杂量对发光性能的影响,并对样品的发光机制进行了探讨,推断出蓝光峰来源于电子由导带底到锌空位(VZn)能级的跃迁及锌填隙(Zni)能级到价带顶的跃迁,它们可通过改变Cu的掺杂量予以控制。 相似文献