Date of Award

2008

Degree Type

Thesis

Degree Name

Master of Science

Program

Chemistry

Supervisor

Dr. Leo W. Lau

Second Advisor

Dr. Ken K. -C. Yeung

Third Advisor

Dr. John F. Corrigan

Abstract

Time-of-flight Secondary Ion Mass Spectrometry (TOF-SIMS) was used to study the effects of primary ion fluence on the technologically important model of a self-assembled monolayer (SAM) of octadecylphosphonic acid molecules, CH3(CH2)17PO(OH)2, on mica. Our measurements show that the intensity of atomic and small fragment ions do not vary by more than 10% for the fluence range of 1010 - 1013 cm2 while the intensity of the parent molecular ion can drop by two orders of magnitude. Primary ion beams of Bist (25keV, 45°), Bi+ (25keV, 45°) and Ar+ (8keV, 45°) all cause substantial intensity changes with the largest damage cross-section (6000 Â2) induced by Bi3+. Static limits were calculated and suggest that the static condition for SAMs becomes questionable when the cumulative primary ion fluence exceeds lxl011 cm'2. Our measurements also show that raising the sample temperature moderately to 50°C can further increase the parent ion damage cross-section via surface thermal diffusion.

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