ABSTRACT
For electron rest mass m0 and velocity v accelerated by the high voltage V, the electron wavelength l is modified according to the relativistic effect as l = +
È
Î Í Í
˘
˚ ˙ ˙
h
m eV eV
m c 2 1
(20.4) where h is Planck’s constant, c is the light velocity, and e is the electric charge. If we substitute Eq. 20.4 in Eq. 20.3, we finally get r h
m eV eV
m c
=
+ È
Î Í Í
˘
˚ ˙ ˙
0 612
2 1
. l NA
(20.5) The acceleration voltage is used to classify the types of TEM since the resolution of the TEM image depends on it, as shown in Table 20.1. Table 20.1 Various types of TEM according to the acceleration voltage
= l (20.6)where d is the gap of the crystal planes, l is the wavelength of the electron, L is the camera length, and R is the gap between a bright spot at the middle of the diffraction pattern and a bright spot of interest (black arrow in Fig. 20.1). If a lattice parameter a d h k l= + +2 2 2 (e.g., acu = 3.61 Å, aPt = 3.92 Å), we can obtain N = h2 + k2 + l2. We finally achieve the crystal plane {h, k, l}, as shown in Table 20.2.
