Laser Vaporization of Clean and CO-Covered Polycrystalline Copper Surfaces

Abstract

Data and results of experiments on the ablation of clean and CO-covered polycrystalline copper surfaces by 248 nm KrF excimer laser pulses of moderate peak power densities (300 MW/cm2 − 1 GW/cm2) are presented. Temperatures of the vaporized copper species were determined from velocity distributions obtained by real time resolved quadrupole mass spectrometry. It was found that the temperatures of neutral copper species (22000 K – 27000 K) in the vapor were significantly higher than the boiling point of copper (2855 K), even near the vaporization threshold for clean polycrystalline copper (300 MW/cm2). Submonolayer coverages of CO on the copper surfaces caused a significant increase in the vaporization threshold absorbed laser power density (> 400 MW/cm2).