Abstract
Electron diffraction patterns from a single crystal of polyvinyl alcohol (PVA) are sharp, but rapidly deteriorated and finally disappeared under the effect of electron bombardment within the microscope, while the shape of the crystals remained unaltered. The spacings of the PVA crystals are gradually increased by electron bombardment. The (101) planes are more affected than the (101) planes. The PVA crystals have a tendency to change from the monoclinic to the orthorhombic cell by electron bombardment. Therefore, electron diffraction pattern must be quickly taken in order to avoid damage due to the electron beam. Then the cell constants of the PVA crystals can be precisely determind as α=7.81±0.02Å, c=5.43±0.01A, β=91°30′±15′. The length of the c-axis obtained from the electron diffraction of the single crystal is slightly shorter than those from X-ray diffraction of PVA fibers.
