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Published May 6, 1999 | public
Journal Article

Positive and Negative Contrast Lithography on Silver Quantum Dot Monolayers


Scanning nonlinear optical microscopy, at a resolution of ∼2 μm, was utilized to examine monolayers of alkylthiol-passivated silver nanocrystals. Selected regions of the monolayers were irradiated with a pulse train of picosecond 1064 nm laser pulses, and then the second harmonic generation (SHG) response of those monolayers was recorded in a second scan. Two lithographic processesone leading to a negative contrast SHG image (observed for particles <4 nm diameter) and a second leading to a positive contrast SH G image (observed for larger particles)were found. These processes are explained within the context of literature models that account for particle size dependent energy partitioning.

Additional Information

© 1999 American Chemical Society. Received 6 January 1999. Published online 21 April 1999. Published in print 1 May 1999. S.E.H., J.L.S., J.J.S., and J.R.H. acknowledge support from an NSF-GOALI grant. J.R.H. acknowledges support from the Alfred P. Sloan Foundation and from the Packard Foundation. C.P.C. and R.J.S. acknowledge support from the NSF. We would like to acknowledge Stan Williams for initially suggesting the possibility of an ionization process in the write step for large particle monolayers.

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