Abstract
The ionic liquid is a salt which is usually liquid at room temperature. The vapor pressure of ionic liquid is so
low that vaporization during experiment is disregarded. The utility of ionic liquid was revealed for the prevention of
charge up phenomenon of fiber samples in the SEM observation. The ionic liquid used in this investigation was 1-ethyl3-methylimidazolium tetrafluoroborate (EMI-BF4). The textile samples were modern hemp, silk and excavated fibers
from a tumulus (early Kofun Period) in Nara prefecture. Prior to the SEM observation, fiber samples were soaked in 0.1
M EMI-BF4 /ethanol solution for 5, 10, 30, 60 minutes, respectively. The all of soaked samples showed distinct SEM
images compared with that of Au-sputtered procedure irrespective of soaking time. The modern silk fibers showed
however clear SEM images only at low magnification. Besides, the SEM images were distorted at high magnification
due to the charge up phenomenon. Though excavated samples also gave clear SEM images, they were separately
investigated by FT-IR microscopy to find out any changes in chemical composition before and after soaking treatment.
Any appreciable changes were not found even after soaking. In summary, EMI-BF4 soaking was superior to prevent the
charge up phenomenon of fibers and hence to obtain clearer SEM images compared with that of Au-sputtering
procedure. Besides, in connection with the versatility of sample preparation procedure, EMI-BF4 is an appropriate
reagent for SEM observation of textile materials.
