Laser induced formation of CO₂ and desorption of O₂ are initiated with femtosecond and picosecond laser excitation of a Pt(111) surface prepared with coadsorbed CO and O₂ at 90 K. The nonlinear fluence dependent reaction yields were measured for 267, 400, and 800 nm wavelengths, and for pulse durations from 80 fs to 3.6 ps. Two-pulse correlation experiments measuring total O₂ desorption yield versus time delay between 80 fs pulses show a 0.9 ps HWHM central peak and a slower 0.1 ns time-scale. At 267 nm the relative yields of O₂ and CO₂ are found to depend on fluence. Comparison of results at different wavelengths and pulsewidths shows that nonthermalized surface electrons play a role in the laser-induced surface chemistry.

Date Published: 25 September 1995
PDF: 9 pages
Proc. SPIE 2547, Laser Techniques for Surface Science II, (25 September 1995); doi: 10.1117/12.221499

Published in SPIE Proceedings Vol. 2547:
Laser Techniques for Surface Science II
Janice M. Hicks; Wilson Ho; Hai-Lung Dai, Editor(s)