Abstract
The mechanisms causing transient 1 93-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 ofwater that rises to 60,000 cm-1 at 163 nm; other evidence shows that this absorption edge shifts toward 1 93 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 1 93-nm probe beam. Based on this evidence, we speculate that 1 93-nm laser ablation of tissue may contain a photothermal component related to dynamic absorption of incident radiation by water.
Original language | English (US) |
---|---|
Pages (from-to) | 176-183 |
Number of pages | 8 |
Journal | Proceedings of SPIE - The International Society for Optical Engineering |
Volume | 2391 |
DOIs | |
State | Published - May 22 1995 |
Event | Laser-Tissue Interaction VI 1995 - San Jose, United States Duration: Feb 1 1995 → Feb 8 1995 |
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Computer Science Applications
- Applied Mathematics
- Electrical and Electronic Engineering