[Study on Self-Absorption Properties in Laser Induced Breakdown Spectroscopy from Copper Sample].

In this paper, a Nd∶YAG laser with an operating wavelength of 532 nm was employed to generate plasmas of TU0 copper sample on the surface. With grating spectrograph and intensified charge coupled device(ICCD) as spectroscopy analysis detection equipment, self-absorption properties of five atomic lines of Cu(Ⅰ) with wavelengths of 324.754, 327.396, 510.554, 515.324 and 521.320 nm have been studied and compared with observation time from 211 to 300 µs after the trigger and laser energy from 30 to 100 mJ. The result indicates that the extents of self-absorption of atomic lines decrease with increasing observation time and after a period of time of 5 to 20 µs the self-absorption cannot be observed; with the increase of laser energy ranging from 50 to 100 mJ, the self absorption shows an increase of extents and duration. Meanwhile the self-absorption properties differ due to different energy-level states of atomic spectrum line transition. Changes of self-absorption extents with observation time and energy and of self-absorption duration with energy exhibit similar characteristics for the two groups of lines range from 324.754 to 327.396 nm and 515.324 to 521.320 nm, respectively, with the same atomic configuration. Moreover, the extents of self-absorption at spectral lines with large angular momentum (324.754 nm，1/2-3/2 and 521.320 nm，3/2-5/2) are more sensitive to change of the laser energy with a higher value of extent change and a longer duration. In comparison, the self-absorption of spectral line 510.554 nm (3d104p-3d94s2) has low extent and short duration when laser energy is below 80 mJ, and the extent increases and the duration becomes longer for the energy range from 80 to 100 mJ.

[XPS and UPS characterization for Cr and Mn in high-temperature oxide films of bulk nanocrystalline 304 stainless steel].

The authors studied the binding energies of valence electrons of two oxide scales, the atomic percentages of Cr and Mn elements in two oxide films, the work function of two oxide films on bulk nanocrystalline 304 stainless steel (BN-SS304) and conventional polycrystalline 304 stainless steel (CP-SS304). BN-SS304 was prepared by severe rolling technique, and the two oxide films were formed in atmosphere at 900 degrees C for 24 hours oxidation on BN-SS304 and CP-SS304 surfaces. In the two oxide films, Cr and Mn elements exist in the forms of Cr3+, Cr0, Mn4+ and Mn0. The atomic percentage ratios of Cr+ / (Cr3+ + Cr0) and Mn4+ / (Mn4+ + Mn0) in the oxide film on BN-SS304 are lower than those in the oxide film on CP-SS304. The interactions of the two oxides and the valence electrons of elements are Mn-O, Cr-O,3d and 4s of Mn0 and Cr0. The binding energies of the valence electrons in the oxide film on BN-SS304 are larger than those in the oxide film on CP-SS304, the work function of the oxide film on BN-SS304 is 0.07 eV larger than that on CP-SS304.

[Polarization-sensitive characteristics of the transmission spectra in photonic crystal with nematic liquid crystal defects].

The polarization-sensitive characteristics in the transmission spectra of TiO2/SiO2 optical multilayer films of one-dimensional photonic crystal (1D PC) with nematic liquid crystal defects were investigated in the present paper. The transmission spectra measurements and simulated results show that the polarization-sensitive feature was obvious when natural light was normal incident onto the parallelly aligned nematic liquid crystal. There were peaks of the extraordinary light (TE mode) with center wavelengths 1831 and 1800 nm and the ordinary light (TM mode) with center wavelengths 1452 and 1418 nm in the photonic forbidden band, respectively. With applied voltage increasing, the peaks of the extraordinary light was blue-shifted, and coincided with the peaks of O light gradually. Their tunable ranges were about 31 and 34 nm, respectively. For the random nematic liquid crystal, polarization sensitivity was not observed. Meanwhile, an individual extraordinary light peak with center wavelength 1801 nm and an individual ordinary light peak with center wavelength 1391 nm were obtained in the photonic forbidden band, respectively. The peaks were also found blue-shifted with applied voltage increasing, and their tunable ranges were about 64 and 15 nm, respectively. The polarization insensitive photonic crystal with nematic liquid crystal defects can be achieved by random liquid crystal molecules, which make the effective refractive index of the extraordinary light equal to that of the ordinary light.