An investigation is made on the optical nonlinear characteristics of MgF₂ films containing Cu nanoparticles. When the Cu volume fraction is 0.1, at approximately \varepsilon_m+ 2\varepsilon_d= 0, the film exhibits a strong third-order optical nonlinear refractive coefficient of 1.0×10^-9 cm²/W, a nonlinear refractive index of about ?4.0×10^-7 esu, a third-order optical nonlinear response of about 6.8×10^-8 esu, and a figure of merit of about 1.0×10^-11. The result shows that the film may have potential applications in optoelectronic technology.

Nano-TiO₂ thin films are deposited by radio frequency (RF) magnetron sputtering using TiO₂ ceramic target and characterized by X-ray diffractometer, atomic force microscope, and ultraviolet-visible spectrophotometer. The photocatalytic activity is evaluated by light-induced degradation of methyl orange solutions (5, 10, and 20 ppm) using a high pressure mercury lamp as the light source. The film is amorphous, and its energy gap is 3.02 eV. The photocatalytic degradation of methyl orange solution is the first-order reaction and the apparent reaction rate constants are 0.00369, 0.0024, and 0.00151 for the methyl orange solution concentrations of 5, 10, and 20 ppm, respectively.

用溅射法在Si片上制备了厚度为140 nm的氧化铟锡(ITO)薄膜。X射线衍射研究表明所制备的薄膜为多晶结构。在1.5～4.5 eV范围内对ITO薄膜进行了椭偏测量。分别用德鲁德洛伦茨谐振子(Drude+Lorenz oscillators)模型、层进模型结合有效介质近似模型对椭偏参量ψ、Δ进行了拟合,得到ITO薄膜的折射指数n的变化范围在1.8～2.6之间,可见光范围内消光系数k接近于零,在350 nm波长附近开始明显变化,且随着波长的减小k迅速增加。计算得到直接和间接光学带隙分别是3.8 eV和4.2 eV。并在1.5～4.5 eV段给出一套较为可靠的、具有实用价值的ITO介电常量和光学常量。

Ag-MgF_(2) composite films with different Ag fractions were prepared through a co-evaporation method. Microstructure analysis shows that the films are composed of amorphous MgF_(2) matrix and embedded fcc-Ag nanoparticles. The optical constants and their dispersion of the films, within the wavelength range of 250-650 nm, were measured by reflecting spectroscopic ellipsometry. The maximum of the imaginary part ε'' of the complex dielectric permittivity attributing to the surface plasmon resonance polarization of the Ag nanoparticles in an Ag-MgF_(2) film, and the tangent of the phase-shift angle δ resulting from the dielectric loss of the film, occur at λ=435 nm and λ=420 nm, respectively. Based on Maxwell-Garnett effective medium theory, the experimentally observed dispersion spectra were reasonably described.

In this paper, the Raman spectrum signal de-noising based on stationary wavelet transform is discussed. Haar wavelet is selected to decompose the Raman spectrum signal for several levels based on stationary wavelet transform. The noise mean square {sigma}_j is estimated by the wavelet details at every level, and the wavelet details toward 0 by a threshold {sigma}_j (2\ln n)^{1/2} , where n is length of the detail, then recovery signal is reconstructed. Experimental results show this method not only suppresses noise effectively, but also preserves as many target characteristics of original signal as possible. This de-noising method offers a very attractive alternative to Raman spectrum signal noise suppress.

Ag-MgF_(2) cermet films with different Ag fractions were prepared by vacuum evaporation. The microstructure of the films was examined by Raman scattering technique. The surface-enhanced Raman spectrum for MgF_(2) molecules in the cermet film strongly suggests the existence of Ag nanoparticles dispersed in MgF_(2) matrix. The intensities of the Raman spectra of Ag-MgF_(2) cermet films increase with Ag fraction. The enhancement of Raman scattering disappears when Ag content reaches wt.20%. The analyses with the transmission electron microscopy showed that Ag-MgF_(2) cermet films are mainly composed of amorphous MgF_(2) matrix with embedded faced-center-cubic Ag nanoparticles. It suggests that the percolation threshold should be around wt.20% of Ag content.