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【期刊论文】A development in the preparation of sharp scanning tunneling microscopy tips
宋建平, J. P. Songa), N. H. Pryds, K. Glejbtil, K. A. March, A. R. ThaIen, and L. N. Christensen
Rev. Sci. Instrum. 64 (4), April 1993,-0001,():
-1年11月30日
An improved and reliable method for making sharp scanning tunneling microscopy (STM) tips is described. It is based on the widely used drop-off electrochemical etching procedure, here modified to improve the control of the tip shape. A second etching is applied not only to remove the oxide layer from the tip surface, but also to sharpen the STM tips further. A tip radius less than 20 nm can be obtained reproducibly. The quality of the produced tips was inspected with transmission electron microscopy, and micrographs of tips produced with different times of second etching are shown. To produce tips which are all without an oxide layer an electronic phase control unit is necessary. Even without this etch controller more than half the tips are oxide free, and then only standard laboratory equipment is used for the tip production,
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宋建平, Yanpeng Zhang, , * Chenli Gan, Long Li, Ruiqiong Ma, Jianping Song, Tong Jiang, Xiaojun Yu, Chuangshe Li, Hao Ge, and Keqing Lu
PHYSICAL REVIEW A 72, 013812 (2005),-0001,():
-1年11月30日
Based on color-locking noisy field correlation, a time-delayed method is proposed to suppress the thermal effect, and the ultrafast longitudinal relaxation time can be measured even in an absorbing medium. One interesting feature in field-correlation effects is that Rayleigh-enhanced four-wave mixing (RFWM) with colorlocking noisy light exhibits spectral symmetry and temporal asymmetry with no coherence spike at γ=0. Due to the interference between the Rayleigh-resonant signal and the nonresonant background, RFWM exhibits hybrid radiation-matter detuning with terahertz damping oscillations. The subtle Markovian high-order correlation effects have been investigated in the homodyne- or heterodyne-detected Rayleigh-enhanced attosecond sum-frequency polarization beats (RASPBs). Analytic closed forms of fourth-order Markovian stochastic correlations are characterized for homodyne (quadratic) and heterodyne (linear) detection, respectively. Based on the polarization interference between two four-wave mixing processes, the phase-sensitive detection of RASPBs has also been used to obtain the real and imaginary parts of the Rayleigh resonance.
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