摘要
Electron emission properties of single-walled carbon nanotubes (SWCNTs) assembled on a tungsten tip were investigated using field emission microscopy (FEM). The transmission electron microscopy (TEM) micrograph confirmed the existence of an SWCNT bundle on the W tip. Under appropriate experimental conditions,a series of FEM patterns with atomic resolution were obtained. These patterns arose possibly from the field emission of the open end of an individual (16,0) SWCNT protruding from the SWCNT bundle. The magnification factor and the resolution under our experimental conditions were calculated theoretically. If the value of the compression factor β was set at β= 1.76, the calculated value of the magnification factor was in agreement with the measured value. The resolving powerof FEM was determined by the resolution equation given by Gomer. The resolutionof 0.277 nm could be achieved under the typical electric field of 5.0×107 V/cm, which was close to the interatomic separation 0.246 nm between carbon atoms along the zigzag edge at the open end for the (16, 0) SWCNT. Consequently, our experimental results were further supported by our theoretical calculation.
Electron emission properties of single-walled carbon nanotubes (SWCNTs) assembled on a tungsten tip were investigated using field emission microscopy (FEM). The transmission electron microscopy (TEM) micrograph confirmed the existence of an SWCNT bundle on the W tip. Under appropriate experimental conditions, a series of FEM patterns with atomic resolution were obtained. These patterns arose possibly from the field emission of the open end of an individual (16,0) SWCNT protruding from the SWCNT bundle. The magnification factor and the resolution under our experimental conditions were calculated theoretically. If the value of the compression factor β was set at β=1.76, the calculated value of the magnification factor was in agreement with the measured value. The resolving power of FEM was determined by the resolution equation given by Gomer. The resolution of 0.277 nm could be achieved under the typical electric field of 5.0×107 V/cm, which was close to the interatomic separation 0.246 nm between carbon atoms along the zigzag edge at the open end for the (16, 0) SWCNT. Consequently, our experimental results were further supported by our theoretical calculation.
基金
the National Natural Science Foundation of China(Grant Nos.69890221 and 69971003)
the MOST of China(No.2001CB610503)
Key Foundation for Science and Technology Research of Education Ministry of China(No.00005)
Scientific Research Foundation for Returned Oversea Chinese Scholars,State Education Commission
作者简介
Correspondence should be addressed to Hou Shimin (email: smhou@ibm320h.phy.pku.edu.cn)
