Characterization of arachidate Langmuir--Blodgett films by variable energy positron beams
Archidate Langmuir-Blodgett (LB) films of different chemical composition and number of monomolecular layers deposited on silylated silica glass substrates were studied by means of positron annihilation spectroscopy. The applied methods included the measurement of the Doppler broadening of the annihilation photopeak with variable energy positron beams and bulk positron lifetime measurements. The studied samples were 58 monomolecular layers (MML) thick Mg- and Cd-arachidate, arachidic acid (50 MML) and a series of Pb-arachidate samples with 4, 10, 20, 40, and 58 MML. The investigation showed that the variable energy positron beam technique is capable of measuring the thickness of the deposited LB films. The measured positron annihilation parameters are sensitive to the chemical composition of the films and the behavior of the films in a vacuum. The results confirmed the stability of salt base LB films in high vacuum conditions and showed the desorption of pure acid films. These investigations have also shown that a strong position trap is formed in the near-surface region of the hydrophobized substrate as a consequence of the silylation process. The results suggest that positron beams provide valuable complementary information to results obtained by other techniques.
- Research Organization:
- Brookhaven National Lab., Upton, NY (US)
- Sponsoring Organization:
- Department of Energy; Hungarian Science Foundation; Hungarian Ministry of culture and Education
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 20004011
- Journal Information:
- Langmuir, Vol. 15, Issue 23; Other Information: PBD: 9 Nov 1999; ISSN 0743-7463
- Country of Publication:
- United States
- Language:
- English
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