Electron holography characterization as a method for measurements of diameter and mean inner potential of hollow nanomaterials

Abstract

In this paper, we provide a method for the simultaneous measurement of the inner diameter of nanotubes with a regular shape and calculation of their mean inner potential (MIP) using electron holography. This method contains 4 steps: (i)phase profile characterization from electron holography; (ii) shape assumption from prepared data; (iii) thickness simulation from a shape assumption and fitting method; (iv) calculation of MIP of the simulated and fitted parameters. By this method, as an example, the shape and the outer and inner diameters of a tube formed from C(60) molecules were characterized. The MIP of the tube was also calculated through this method. The MIP calculation from another nano whisker formed from C(60) molecules supports the feasibility of our method and it could be extended to other nanomaterials. This work provides a convenient method for morphology characterization of hollow nanomaterials, such as diameter measurements and cross-sectional shape determination, which are the most basic and important characteristics of the nanomaterials. In addition, it also provides a method for MIP calculation without a thickness measurement if the samples have relatively regular shapes. Thus this method should be more convenient for closely combining the tomography and physical properties of samples, which could be essential for in situ TEM studies of nanomaterials.

The structural transitions of C60 nanowhiskers under an electric field characterized by in situ transmission electron microscopy and electron energy-loss spectroscopy

“…25 Using electron holography, we can easily distinguish between the C 60 nanowhiskers and nanotubes. 26 The resistance of the C 60 nanowhiskers measured by an in situ TEM electrical probing system is about 10 MU, which is two orders of magnitude higher than the resistance obtained by the four probe method. 18 This implies that there is a large contact resistance between the gold tip and the C 60 nanowhisker.…”

Calibration for medium resolution off-axis electron holography using a flexible dual-lens imaging system in a JEOL ARM 200F microscope

“…The method to be described allows a calibrated setup for predefine FOV ranging from 35 nm to 2500 nm, ideal for the characterization of materials in nanotechnology from where we can extract quantitative information such as, e.g., electrostatic fields [4-9], magnetic fields [10-16], non-stained biological samples [17-18], determination of the thickness and surface morphology in nanostructured materials [19-21], dopant profiles and strain measurement in semiconductor technology [22-29]. New developments in improving the reconstructed phase and to avoid Frensel fringes can be obtained by novel configurations as the double or triple biprims in the microscope as well as a modified Lorentz conditions by controlling the diffraction lens in the microscope [30-32].…”