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Science 10 May 2002:
Vol. 296. no. 5570, pp. 1106 - 1109
DOI: 10.1126/science.296.5570.1106
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Reports

An Efficient Two-Photon-Generated Photoacid Applied to Positive-Tone 3D Microfabrication

Wenhui Zhou,1 Stephen M. Kuebler,1 Kevin L. Braun,1 Tianyue Yu,3 J. Kevin Cammack,1 Christopher K. Ober,3* Joseph W. Perry,12* Seth R. Marder12*

A two-photon-activatable photoacid generator, based on a bis[(diarylamino) styryl]benzene core with covalently attached sulfonium moieties, has been synthesized. The photoacid generator has both a large two-photon absorption cross section (delta  = 690 × 10-50 centimeter4 second per photon) and a high quantum yield for the photochemical generation of acid (phi H+ = 0.5). Under near-infrared laser irradiation, the molecule produces acid after two-photon excitation and initiates the polymerization of epoxides at an incident intensity that is one to two orders of magnitude lower than that needed for conventional ultraviolet-sensitive initiators. This photoacid generator was used in conjunction with a positive-tone chemically amplified resist for the fabrication of a three-dimensional (3D) microchannel structure.

1 Department of Chemistry,
2 Optical Sciences Center, University of Arizona, Tucson, AZ 85721, USA.
3 Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853, USA.
*   To whom correspondence should be addressed. E-mail: cober{at}ccmr.cornell.edu (C.K.O.); jwperry{at}u.arizona.edu (J.W.P.); smarder{at}u.arizona.edu (S.R.M.).

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Gold Helix Photonic Metamaterial as Broadband Circular Polarizer.
J. K. Gansel, M. Thiel, M. S. Rill, M. Decker, K. Bade, V. Saile, G. von Freymann, S. Linden, and M. Wegener (2009)
Science 325, 1513-1515
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