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Proceedings Paper

Effect of hydrogen bonding on far-ultraviolet water absorption and potential implications for 193-nm ArF excimer laser-tissue interaction
Author(s): Joseph T. Walsh Jr.; Paul T. Staveteig
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Paper Abstract

The mechanisms causing transient 193-nm optical absorption of collagen during ablative-fluence ArF excimer pulses are poorly understood. The preponderance of hypotheses proposed to explain this phenomenon, such as ultrafast secondary-structure denaturation of proteins and transient free radical formation, focus on the protein matrix and ignore potential contributions from other tissue components such as water. A substantial body of spectroscopic literature places 193 nm adjacent to a steep absorption edge of water that rises to 60,000 cm-1 at 163 nm; other evidence shows that this absorption edge shifts toward 193 nm upon hydrogen-bond breakage. In this paper we show that heating of water from 20-100°C increases the liquid's absorption coefficient. Further investigations using an infrared pump laser show a significant increase in absorption by water of a 193-nm probe beam. Based on this evidence, we speculate that 193-nm laser ablation of tissue may contain a photothermal component related to dynamic absorption of incident radiation by water.

Paper Details

Date Published: 22 May 1995
PDF: 8 pages
Proc. SPIE 2391, Laser-Tissue Interaction VI, (22 May 1995); doi: 10.1117/12.209880
Show Author Affiliations
Joseph T. Walsh Jr., Northwestern Univ. (United States)
Paul T. Staveteig, Northwestern Univ. (United States)

Published in SPIE Proceedings Vol. 2391:
Laser-Tissue Interaction VI
Steven L. Jacques, Editor(s)

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