Physics Commons^™

Laser Ablation Of Optically Thin Absorbing Liquid Layer Predeposited Onto A Transparent Solid Substrate, S. I. Kudryashov, K. Lyon, S. D. Shukla, D. Murry, S. D. Allen

Mechanical Engineering - Daytona Beach

Ablation of optically thin liquid 2-propanol layers of variable thickness on IR-transparent solid Si substrate by a nanosecond CO ₂laser has been experimentally studied using time-resolved optical interferometric and microscopy techniques. Basic ablation parameters - threshold fluences for surface vaporization and explosive homogeneous boiling of the superheated liquid, ablation depths, vaporization (ablation) rates, and characteristic ablation times versus laser fluence - were measured as a function of alcohol layer thickness. The underlying ablation mechanisms, their thermodynamics, and microscopic details are discussed.

c 2006 American Institute of Physics

Carrier Dynamics In Α‐Fe2o3 (0001) Thin Films And Single Crystals Probed By Femtosecond Transient Absorption And Reflectivity, Alan G. Joly, Joshua R. Williams, Scott A. Chambers, Gang Xiong, Wayne P. Hess, David M. Laman

All Faculty Scholarship for the College of the Sciences

Femtosecond transient reflectivity and absorption are used to measure the carrier lifetimes in α‐Fe₂O₃ thin films and single crystals. The results from the thin films show that initially excited hot electrons relax to the band edge within 300 fs and then recombine with holes or trap within 5 ps. The trapped electrons have a lifetime of hundreds of picoseconds. Transient reflectivity measurements from hematite (α‐Fe₂O₃)single crystals show similar but slightly faster dynamics leading to the conclusion that the short carrier lifetimes in these materials are due primarily to trapping to Fe d- …

Influence Of Thickness On Optical Properties Of A: As_2se_3 Thin Films, Dinesh C. Sati, Rajendra Kumar, Ram Mohan Mehra

Turkish Journal of Physics

This paper reports optical properties of amorphous chalcogenide thin films of As_2Se_3 of different thicknesses 2000-6800 Å. The transmittance and reflectance of thin films were measured in the wavelength range 500-1000 nm. It was found that the optical band gap increases with film thickness. Variation of refractive index n and extinction coefficient k with thickness have been studied to analyze optical efficiency of the As_2Se_3 thin films. The dielectric behavior of the films has also been studied and high frequency dielectric constants \varepsilon_{\infty} has been estimated as a function of thickness of films.