激光光控超导YBa2Cu3Ox薄膜开关的研制

在对光控热电效应开关进行理论分析的基础上,木文提出用YBa₂Cu₃O_x薄膜制作光控开关,并测试了在液氮温度下薄膜开关在不同激光波长下的特征参数,测试的最好结果是响应度R_v(632.8nm,10kHz,1Hz)为217V/W,归一化探测率D_*(632.8nm,10kHz,1Hz)为2.3×10¹¹cm.Hz^1/2/W,响应时间τ为0.21ms.     

SERS activity of pulsed laser ablated silver thin films with controlled nanostructure

The surface‐enhanced Raman scattering (SERS) activity of silver thin films deposited by the pulsed laser ablation technique was investigated. The samples were grown in a controlled Ar atmosphere at pressures ranging between 10 and 70 Pa, and changing the number of laser pulses. Different surface morphologies, from isolated nearly spherical nanoparticles (NPs) to larger islands with smooth edges, were observed by means of scanning and transmission electron microscopies, as a function of the different deposition conditions adopted. SERS measurements were performed by soaking the samples in rhodamine 6G aqueous solutions over the concentration range between 1.0 × 10⁻⁴ and 5.0 × 10⁻⁸ M . Raman spectra were acquired using both the 632.8 and 514.5 nm excitation sources. The dependence of the SERS activity of the samples on the observed surface morphology is presented and discussed. The presence of the so called hot spots is envisaged. Copyright © 2011 John Wiley & Sons, Ltd.     

Vibrational spectra of a single crystal of lead germanate and the effect of RS amplification on its surface

For single crystal wafers of lead germanate cut perpendicularly to the C-axis an investigation has been made of IR transmission and RS spectra atλ _exc =632.8, 514.5, and 488 nm in the spectral range of 400–1800 cm⁻¹. An interpretation of the spectra recorded is suggested. In the RS spectra specific features of line intensity distributions are detected. The dependences of the intensity distribution in the peculiarities detected on the excitation wavelength and the angle of incidence of exciting radiation and transmission of the reflected exciting laser beam relative to the optical axis of illumination of the spectrometer inlet slit are investigated. The reason for the occurrence of these specific features is suggested: the interference of RS radiation and exciting laser radiation diffracted on the non-working narrow sides of the diffraction gratings of the spectrometer. The possibilities of amplifying the spectral lines in the RS spectra by imposing diffracted one-mode exciting radiation on them are discussed. Translated from zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 2, pp. 220–226, March–April, 1999.     

Raman scattering and luminescence of yttria nanopowders and ceramics

We have studied Raman scattering in yttria nanopowders and ceramics that was excited by radiation at wavelengths of 514.5 and 632.8 nm. We show that, in undoped nanopowders and cubic phase of doped yttria ceramics, only the Raman scattering by phonons is observed, with no other Raman scattering centers having been revealed. In nanopowders of the monoclinic phase, we have observed an additional Raman line with a Raman shift of 1093 ± 4 cm^?1. If all the objects under investigation are excited by the radiation at a wavelength of 514.5 nm, their spectra exhibit four series of photoluminescence lines, two of which (at λ = 521–523 and 538–564 nm) are emitted by Er³⁺ ions, “impurity” dopants, while the other two lines (at λ = 607–635 and 644–684 nm) are emitted by intrinsic centers. Under excitation by the radiation at a wavelength of 632.8 nm, only a series of bands at λ = 644–684 nm is emitted. In addition to these photoluminescence bands, neodymium-doped ceramics show photoluminescence bands of Nd³⁺ ions. We have shown that intrinsic luminescence centers, which occur in all the examined specimens, are capable of acting as acceptors with respect to neodymium ions excited to the upper laser level.     

Anomalies of the photo-response and thermal boundary resistance of a YBaCuO/YSZ structure

The photoresponse of a YBaCuO/ZrO₂ bolometric structure was measured under modulated (λ = 630 nm) and pulsed (τ ≈ 7 – 8 ns; λ = 337 nm) laser excitation. The shape of the measured photoresponse was interpreted by a thermal model; nevertheless, the pulse amplitude for vanishing YBaCuO film resistance was 5–6 times greater than predicted; the thermal boundary resistance R_Bd between YBaCuO and YSZ was evaluated ? 10^?2 K × cm²/Watt, which is considerably larger than estimated theoretically for the similar situation of YBaCuO/MgO [5].     

6H-SiC（0001）-6[KF（]3[KF）]×6[KF（]3[KF）]R30°重构表面的同步辐射角分辨光电子能谱研究

利用同步辐射角分辨光电子能谱（SRARPES）对6H-SiC（0001）-6[KF（]3[KF）]×6[KF（]3[KF）] R30°重构表面的电子结构和表面态进行了研究.通过鉴别价带谱中来自于体态的信息,可以推断出重构表面的费米能级位于体态价带顶之上（2.1±0.1）eV处.实验测出的体能带结构与理论计算的结果较为符合.在重构表面上发现三个表面态,分别位于结合能-0.48 eV（S₀）,-1.62 eV（S₁）和-4. 关键词： 角分辨光电子能谱 碳化硅（SiC） 电子结构 表面态     

ZnWO4∶Sm3+晶体光谱与上转换发光

采用Czochralski法生长出了ZnWO₄∶Sm³⁺单晶(Sm₂O₃=0.1wt%)，测量了晶体的吸收光谱.利用激光Raman谱仪在He-Ne激光器632.8nm波长激光激发下，观测到448，471，505，533nm的上转换锐线荧光，对其发光机理进行了探讨. 关键词：     

Mass measurements in the endpoint region of the rp-process at SHIPTRAP

The Penning-trap mass spectrometer SHIPTRAP was designed for precision mass measurements of radionuclides produced in fusion–evaporation reactions. The latest measurement campaign covered heavy nuclei (A>90) related to the astrophysical rapid proton capture process. The masses of 34 neutron-deficient radionuclides have been measured since February 2006 with relative uncertainties between 5×10⁻⁸ and 1×10⁻⁷. Furthermore, the use of an octupolar RF excitation for the time-of-flight ion-cyclotron-resonance technique was investigated and an increase of the resolving power by a factor of ten was observed in agreement with simulations. This will allow to resolve isomeric states with excitation energies of a few 10 keV only.      

Growth and optical properties of paraelectric K<Subscript>1-y</Subscript>Na<Subscript>y</Subscript>Ta<Subscript>1-x</Subscript>Nb<Subscript>x</Subscript>O<Subscript>3</Subscript> single crystals

We report the successful growth of an electroholographic crystal, potassium sodium tantalate niobate (KNTN), by a top-seeded solution growth method. Both blue and colorless crystals were obtained. The structure, optical absorption, and refractive dispersion properties of the as-grown crystals have been investigated. Furthermore, the Kerr coefficients R₁₁ and R₁₂ of paraelectric K_0.95Na_0.05Ta_0.61Nb_0.39O₃ single crystal were determined by using an automated scanning Mach–Zehnder interferometer. The crystal has large Kerr coefficients with R₁₁= 2.8×10^-16 m²/V² and R₁₂= -0.3×10^-16 m²/V² at the wavelength of 632.8 nm near its cubic–tetragonal phase boundary. PACS 81.10.Dn; 42.70.Nq     

Tm3+/Yb3+共掺铋碲酸盐玻璃中的高效蓝色上转换荧光

制备了高折射率Tm³⁺/Yb³⁺共掺杂铋碲酸盐玻璃，利用棱镜耦合法测量出玻璃在632.8和1550nm波长处的折射率分别为2.0365和1.9795. 对玻璃的吸收、荧光和红外透过光谱展开了测试与分析，根据Judd-Ofelt理论对吸收光谱进行拟合，求得Tm³⁺的振子强度参数Ω_t(t=2，4，6)分别为3.90×10^-20, 2.03×10^-20和9.03×10^{-2 关键词： 3+}/Yb³⁺共掺')" href="#">Tm³⁺/Yb³⁺共掺 铋碲酸盐玻璃 光谱参数 上转换荧光     

Optical parameters measurement for diagnostic and photodynamic therapy of human cervical adenocarcinoma (HeLa) cell line

The purpose of this study was to investigate the optical properties, absorption coefficient (μ _a ) scattering coefficient (μ _s ) and refractive indices, (n) of HeLa cell line in a suspension of 2% minimum essential medium (MEM) at two different (632.8 and 532.0 nm) wave lengths of laser light. Optical properties were determined with Kubelka Munk Model (KMM) and refractive index measurement was made through minimum angle of deviation method (MAD). We reported μ _a = 8.643 ± 0.187 and 2.348 ± 0.249 cm⁻¹ and μ _s = 5.609 ± 0.287 and 88.166 ± 2.833 cm⁻¹ at 632.8 and 532.0 nm, respectively. Refractive index was found to be 1.332 and 1.312 at 632.8 nm and 532.0 nm, respectively. The discussed results provide a route of information for clinical diagnosis, therapeutic application and dosimetry studies in HeLa and other cell lines.     

Multiexcitation Raman Spectroscopy in Identification of Chinese Jade

The high-fluorescence background of jade creates a great impact on the Raman spectra measurements that impedes their application in jade analysis and treatment, particularly with ancient jade. The five most important materials of Chinese ancient jade are amphibole, serpentine, turquoise, agate/chalcedony, and anorthite-zoisite (Dushan jade). This study comparatively analyzed the Raman spectra of different wavelengths' excitation light sources (514.5 nm, 632.8 nm, 785 nm) in identifying these Chinese jades, and this article discusses the most applicable ones to the analysis of different jade materials. The results show that although 632.8 nm He-Ne laser is appropriate for turquoise jades, generally speaking, Raman spectra produced by the 785 nm semiconductor laser and the 632.8 nm He-Ne laser are better for most kinds of jades than the spectra produced by the 514.5 nm argon ion laser, and both of them can be effectively used jointly in research by nondestructive phase analysis of Chinese ancient jade.     

Measurement of the absolute Raman scattering cross sections of sulfur and the standoff Raman detection of a 6‐mm‐thick sulfur specimen at 1500 m

The absolute Raman scattering cross sections (σ_RS) for the 471, 217, and 153 cm⁻¹ modes of sulfur were measured as 6.0 ± 1.2 × 10⁻²⁷, 7.7 ± 1.6 × 10⁻²⁷, and 1.2 ± 0.24 × 10⁻²⁶ cm² at 815, 799, and 794 nm, respectively, using a 785‐nm pump laser. The corresponding values of σ_RS at 1120, 1089, and 1081 nm were determined to be 1.5 ± 0.3 × 10⁻²⁷, 1.2 ± 0.24 × 10⁻²⁷, and 1.2 ± 0.24 × 10⁻²⁷ cm² using a 1064‐nm laser. A temperature‐controlled, small‐cavity (2.125 mm diameter) blackbody source was used to calibrate the signal output of the Raman spectrometers for these measurements. Standoff Raman detection of a 6‐mm‐thick sulfur specimen located at 1500 m from the pump laser and the Raman spectrometer was made using a 1.4‐W, CW, 785‐nm pump laser. Copyright © 2010 John Wiley & Sons, Ltd.     

Precision heterodyne measurements of ozone spectral lines near 9.5 μm

Precision measurements of 26 individual spectral lines of ozone near 9.5 μm were made using the GSFC infrared heterodyne spectrometer. The line profiles of 26 lines in near coincidence with the emission lines from a ¹²C¹⁶O₂ laser local oscillator were measured at resolving powers of 6 × 10⁶. The retrieved absolute line center frequencies, accurate to ±3 MHz, and the relative line intensities were compared to previous experimental results and theoretical calculations.     

Macroscopic and microscopic parameters of laser dye solvents: m-xylene and dioxane

For the laser designer and other users the optical, electrical and refractive parameters have been obtained for pure nonpolar laser dye solvents m-xylene and dioxane. The refractive index (n) and its thermo-optic constant (dn/dT) at argon laser wavelength 514.5 nm and He–Ne laser wavelength 632.8 nm, are measured. The values of n and dn/dT are used to calculate the optical permittivity ε=n² and its variation with temperature dε/dT. Applying Cauchy's equation the optical and dielectric dispersion (dn/dλ and dε/dλ) are determined. The variation of −dn/dT, −dε/dT, molar refractivity and thermal volume expansion coefficient as a function of wavelength are calculated and represented. Furthermore Cauchy's constants A and B as a function of temperature are plotted. The specific and molar refractivities, specific and molar dispersivity total polarizability, distortion polarizability, ratio of atomic to electronic polarizability, molecular radius, relaxation time, electric susceptibility characteristic impedance, and other physical parameters were calculated. Additionally, density, thermal linear expansion coefficient and molar polarization as a function of temperature were calculated at the laser wavelengths 514.5 nm.     

A liquid helium cooled Fabry-Perot spectrometer for ballon-borne astronomical observations

A liquid helium cooled Fabry-Perot spectrometer optimized for wide-beam observations of the interstellar [C⁺]158 μm line with the aid of a balloon-borne telescope is described. Particular attention is given to the design and the performance of the Fabry-Perot meshes, which consist of gold grids on crystal quartz substrates. Under flight conditions the resolving power of the spectrometer is 775 and the system sensitivity is 6 × 10⁻¹⁸W/cm² (3σ in 15 min) at the wavelength of the carbon line, all in good agreement with the laboratory measurements.     

Tunable,narrow bandwidth, 2 MW dye laser pumped by a KrF1 discharge laser

Characteristics of p-terphenyl and PBD, the most efficient uv dyes, have been investigated under high intensity pumping by a multi-atmosphere KrF¹ discharge laser at 248 nm wavelength. Energy conversion efficiencies, spectral features and temporal behaviour of the dyes were studied parametrically. A maximum powerof 2 MW uv emission with a bandwidth of ～2×10^-2 nm was obtained for PBD. It was found that a mixture of both dyes provided higher (by a factor of 1.3) output in the range 348–366 nm than either of the dyes alone. Significant pump intensity dependent conversion efficiency and pulse shape variations were observed for the most efficient uv dye, p-terphenyl and were related to triplet-triplet adsorption processes in the dye.     

The measurement of energy spectra of neutral particles in low energy ion scattering

An apparatus is described for low energy (0.1–10 keV) ion scattering (LEIS) experiments. A time of flight (TOF) spectrometer is incorporated in the system to be able to measure the energy of particles in the neutral state after scattering. The energy resolution ΔE/E of the TOF spectrometer is discussed and found to be 0.5% (FWHM). This is sufficient for our scattering experiments. An electrostatic analyzer (ESA) is used to measure the energy of scattered ions [ΔE/E=0.5% (FWHM)]. Experiments show that in general the ion dose needed to obtain a TOF spectrum (2×10¹⁰ ions/cm²) is much smaller than the dose needed for an ESA-spectrum (6×10¹³ ions/cm²). The ion spectra measured with the TOF spectrometer, by subtracting the neutral yield from the total yield, as well as with the ESA are found to agree quite well. This provides a way to calibrate the TOF spectrometer. The determination of the ion fraction of scattered particles is discussed [10 keV⁴⁰Ar⁺ on Cu(100), scattering angle 30°]. It is shown that the TOF spectrometer is able to measure light recoil particles (e.g. hydrogen) from a heavy substrate. In the analysing system is, in addition to the TOF spectrometer, also incorporated a stripping cell to measure the energy of neutral scattered particles. An energy spectrum of neutral scattered particles measured with both methods is shown.     

Measurement of the absolute Raman scattering cross section of the 1584‐cm−1 band of benzenethiol and the surface‐enhanced Raman scattering cross section enhancement factor for femtosecond laser‐nanostructured substrates

The absolute Raman scattering cross section (σ_RS) for the 1584‐cm⁻¹ band of benzenethiol at 897 nm (1.383 eV) has been measured to be 8.9 ± 1.8 × 10⁻³⁰ cm² using a 785‐nm pump laser. A temperature‐controlled, small‐cavity blackbody source was used to calibrate the signal output of the Raman spectrometer. We also measured the absolute surface‐enhanced Raman scattering cross section (σ_SERS) of benzenethiol adsorbed onto a silver‐coated, femtosecond laser‐nanostructured substrate. Using the measured values of 8.9 ± 1.8 × 10⁻³⁰ and 6.6 ± 1.3 × 10⁻²⁴ cm² for σ_RS and σ_SERS respectively, we calculate an average cross‐section enhancement factor (EF) of 0.8 ± 0.3 × 10⁶. Copyright © 2009 John Wiley & Sons, Ltd.     

A tunable,frequency-doubled cw dye laser using an RDP crystal

We report a c.w. intracavity, frequency doubled, rhodamine B dye laser using an RDP crystal 5 cm long. Generated uv powers up to 15 mW are obtained in a single direction with a linewidth of 2 GHz over the range 314–318 nm. A conversion efficiency of about 1.25 × 10^-3 W^-1 is measured.