表面科学研究回顾与21世纪发展展望

表面与界面是材料物理、化学性质发生空间突变的二维区域,材料的许多重要物理、化学过程首先发生在表面,同时材料的很多破坏和失效也首先起源于表面和界面。因此,表面是材料与外部环境直接发生联系的窗口,从研究材料表面界面的各种物理化学过程入手最终可以达到改善材料性能的目的。过去１０年中,材料表面科学在促进材料科学基础研究、推动新材料新技术发展中发挥了关键作用。世纪之交乃至下一世纪,表面科学将面临新的挑战和机     

GROWTH MODEL OF TEXTURED DIAMOND (111) FILM IN CH4/O2/H2 ATMOSPHERE

Partially oriented and highly textured diamond films on Si( 111 ) substrates were achieved by hot-filament chemical vapor deposition(HFCVD). High nucleation density greater than 5×10⁸cm^-2 was realiged in 3 min by near-surface glow discharge. The os-grown films were characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD) and Raman spectroscopy. It was found that by adding a small amount of oxygen to the mixture of CH₄/H₂, the appearance of facet(111) was well controlled, and the secondary nucleation on the facet(111) was suppressed greatly. Growth feature of homoepitaxy on diamond (111) surface was demonstrated to be in Stranski-Krastanov model by SEM.     

ArCN三原子准分子的研究(Ⅰ)——电子态的量子化学计算

分别采用６－３１Ｇ＊，６－３１Ｇ?＊基组对线性ＡｒＣＮ分子的X²∑⁺，Ａ²∏_i，Ｂ²∑⁺，Ｃ²∏_i，Ｄ²∑⁺和Ｅ²∏_r ６个电子态进行了从头计算法开壳自旋限制Ｈａｒｔｒｅｅ－Ｆｏｃｋ（ＲＯＨＦ）计算。计算结果表明线性ＡｒＣＮ分子的电子态具有典型的准分子结构，从而可以肯定ＣＮ与稀有气体原子Ｒｇ（Ａｒ，Ｋｒ，Ｘｅ）能够形成自由基准分子。对Ｘ²∑⁺，Ａ²∏_i的自旋非限制Ｈａｒｔｒｅｅ－Ｆｏｃｋ（ＵＨＦ）计算证实较大的自旋污染不影响势能曲线的形状。 关键词：     

FOURIER ANALYSIS OF TEMPORAL AND SPATIAL OSCILLATIONS OF TUNNELING CURRENT IN SCANNING TUNNELING MICROSCOPY

Partially oxidized Si(111) surfaces and surfaces of highly oriented pyrolytic graphite (HOPG) were studied by two different ultrahigh vacuum scanning tunneling microscope (UHV-STM) systems and by an STM system working under ambient conditions, respectively. The STM current images of partially oxidized Si(111) surfaces and HOPG surfaces were analyzed by one/two-dimensional fast Fourier transformation (1D-FFT/2D-FFT). The phenomenon of temporal oscillations of tunneling current on the partially oxidized Si(111) surfaces was detected with both UHV-STM systems. Temporal as well as spatial oscillations of tunneling current appeared in highly resolved STM current images of the Si(111) surfaces simultaneously, but both kinds of oscillations could be discriminated according to their different influence on the 2D-FFT spectra of the current images, while varying the scanning range and rate. On clean HOPG surfaces only spatial oscillations of tunneling current induced by the surface structure were observed.     

GROWTH MODEL OF TEXTURED DIAMOND (111) FILM IN CH4/O2/H2 ATMOSPHERE

Partially oriented and highly textured diamond films on Si( 111 ) substrates were achieved by hot-filament chemical vapor deposition(HFCVD). High nucleation density greater than 5×10⁸cm^-2 was realiged in 3 min by near-surface glow discharge. The os-grown films were characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD) and Raman spectroscopy. It was found that by adding a small amount of oxygen to the mixture of CH₄/H₂, the appearance of facet(111) was well controlled, and the secondary nucleation on the facet(111) was suppressed greatly. Growth feature of homoepitaxy on diamond (111) surface was demonstrated to be in Stranski-Krastanov model by SEM.     

He/Ar/Kr/F_2混合气体中准分子KrF~*和Kr_2F~*的动力学研究

本文用时间积分谱的方法研究了快放电激励下He/Ar/Kr/F_2混合气体中Kr_2F~*的动力学,探讨了Kr_2F~*形成的通道特性,理论分析和实验结果表明,在快放电激励下,三体碰撞过程KrF~* Kr M→Kr_2F~* M是形成Kr_2F~*的主要通道,而置换反应ArF~* Kr→KrF~* Ar又能有效地产生KrF~*。实验测量了Kr_2F~*形成的有关速率常数。     

水杨酸钠在极性溶剂中的荧光和激光特性的研究

采用XeCl激光作为泵浦源,首次系统研究了水杨酸钠在水、甲醇、乙醇以及水醇混合物等极性溶剂中的荧光和激光特性.探明它有很强的激发态自吸收作用.从分子结构的角度分析了水杨酸钠荧光积分强度的温度特性.     

PHOTOLUMINESCENCE OF NANOCRYSTALLINE SiC FILMS PREPARED BY RF MAGNETRON SPUTTERING

Amorphous SiC films are deposited on Si (111) substrates by rf magnetron sputtering and then annealed at 1200℃ for different times by a dc self-heating method in a vacuum annealing system. The crystallization of the amorphous SiC is determined by Raman scattering at room temperature and X-ray diffraction. The experimental result indicates that the SiC nanocrystals have formed in the films. The topography of the as-annealed films is characterized by atomic force microscopy. Measurements of photoluminescence of the as-annealed films show blue or violet light emission from the nanocrystalline SiC films and photoluminescence peak shifts to short wavelength side as the annealing time decreases.     

He/Ar/Kr/F2混合气体中准分子KrF*和Kr2F*的动力学研究

本文用时间积分谱的方法研究了快放电激励下He/Ar/Kr/F₂混合气体中Kr₂F^*的动力学,探讨了Kr₂F^*形成的通道特性,理论分析和实验结果表明,在快放电激励下,三体碰撞过程KrF^*+Kr+M→Kr₂F^*+M是形成Kr₂F^*的主要通道,而置换反应ArF^*+Kr→KrF^*+Ar又能有效地产生KrF^*。实验测量了Kr₂F^*形成的有关速率常数。 关键词：