Carmen S. Menoni

Scandium Oxide Thin Films Deposited by Dual Ion Beam Sputtering for High-Power Laser Applications

Scandium oxide films were deposited using reactive dual ion beam puttering. At 1 micron, the refractive index of the films is 1.95 and the absorption loss is 18.5 ppm. X-ray photoelectron spectroscopy showed oxygen defects.

Depth-profiling Microanalysis of CoNCN Water-oxidation Catalyst using a λ=46.9 nm Plasma-Laser for Nano-Ionization Mass Spectrometry

Nanoscale depth profiling analysis of a CoNCN-coated electrode for water oxidation catalysis was carried out using table-top extreme ultraviolet (XUV) laser ablation time-of-flight mass spectrometry. The self-developed laser operates at λ = 46.9 nm and represents factor of 4 reduction in wavelength with respect to the 193 nm excimer laser. The reduction of the wavelength is an alternative approach to the reduction of the pulse duration, to enhance the ablation characteristics and obtain smaller quasi-nondestructive ablation pits. Such a XUV-laser ablation method allowed distinguishing different composite components of the catalyst-Nafion blend, used to modify a screen-printed carbon electrode surface. Chemical information was extracted by fragment assignment and relative amplitude analysis of the mass spectrometry peaks. Pure Nafion and the exposed carbon substrate were compared as references. Material specific fragments were clearly identified by the detected nonoverlappingxa0mass-to-charge peaks of Nafion and CoNCN. Three dimensional mapping of relevant mass peak amplitudes was used to determine the lateral distribution and to generate depth profiles from consecutive laser pulses. Evaluating the profiles of pristine electrodes gave insight into fragmentation behavior of the catalyst in a functional ionomer matrix and comparison of post-catalytic electrodes revealed spots of thin localized Co residues.

Multiple Subpicosecond Pulse Laser Damage Behavior of Optical Coatings in a Vacuum Environment

The multiple-pulse damage threshold of dual-ion beam sputtered films show a drop to just 10% of the single-pulse damage threshold when tested in high vacuum. The drop is related to the background pressure of water vapor. Optical microscopy shows a change in the damage morphology.