AVS 47th International Symposium
    Vacuum Technology Wednesday Sessions
       Session VT-WeP

Paper VT-WeP9
Cleaning of Artificial Contamination on Aluminum Surface for Ultra-high Vacuum Treated in Supercritical Fluid and Evaluated with FT-IR

Wednesday, October 4, 2000, 11:00 am, Room Exhibit Hall C & D

Session: Poster Session
Presenter: T. Momose, Miyagi National College of Technology, Japan
Authors: T. Momose, Miyagi National College of Technology, Japan
H. Mishina, Miyagi National College of Technology, Japan
Y. Ikushima, National Industrial Research Institute of Tohoku, Japan
K. Tatenuma, Kaken Corp., Japan
T. Goto, Miyagi National College of Technology, Japan
M. Takahara, Miyagi National College of Technology, Japan
Correspondent: Click to Email
To decrease outgassing rate of the surface for ultra-high vacuum materials, clean surface is required. We have paid attention on native contamination of the surface.@footnote 1@ Here, cleaning test of the artificial contamination which can be deposited on the surface during treatments is carried out using supercritical fluid(SCF) CO@sub2@ with high solubility for organic materials. Triglyceryde is selected as a contamination because it is the main ingredient of grease of human body. The triglyceryde was deposited on mirror surface of aluminum circular discs(5 mm in diameter) by evaporating ether-triglyseride solutions. The disc was kept in SCF CO@sub2@ for a half hour at 40°C and a fixed pressure. The surface was evaluated from the CH@sub2@- and CH@sub3@- peaks of FTIR spectra. The standard lines of the peaks were obtained from the ones of FT-IR as a function of the density of ether-triglyceride solution. Removing rate was calculated from the ratio, (Lo-Li)/Lo x 100 %, where Lo is the peak height before treatment and Li the one after treatment. The deposited thickness between one µm and 21 µm was proportional to a square root of density of the solution (1%-30%). Precision of removing rate was ±13 %. The removing rate was proportional to pressure, 40 to 100 % in the range from 100 atm to 250 atm, where it was 100 % in the range from 250 atm to 300 atm. The data showed that the cleaning using SCF CO@sub2@ is promising to remove artificial contamination like the ones on the order of µm thick. @footnote 1@ T.Momose et.al, JVST, A17(4), Jul/Aug, 1999, 1391.