Search

The article discusses a recently developed nonperturbative quantum theory, which explains the phonon-assisted photon absorption of conduction band electron in intense laser.

Abstract: The effect of Ge addition on the microstructure, transformation temperatures and mechanical properties of (Ni56.5Fe17Ga26.5)100−x Ge x ferromagnetic shape memory alloys was investigated. With the increase of Ge content in these alloys the martensitic transformation temperatures decrease almost linearly from higher than 100°C down to −70°C or even lower that is attributed to the change of the electron concentrations of the Ni–Fe–Ga(Ge) alloys. The addition of Ge also significantly enhances the compression strength and the ductility of the alloys. The determined relationships between transformation temperatures and the mechanical properties and the Ge content will be useful for designing a suitable Ni–Fe–Ga(Ge) alloy device with a required martensitic transformation temperature and optimized mechanical property. [Copyright &y& Elsevier]

Abstract: SiO2 films were deposited on K9 substrate by the electron-beam evaporation method. The influence of oxygen-plasma posttreatment on the properties of SiO2 films was investigated. After oxygen-plasma treatment, it was found that the microdefect density of films reduced. We deduced that the absorption of films also reduced. The treated sample exhibited higher LIDT value compared with the as-deposited sample. However, this study is the preliminary work and optimization by this method will be discussed in our future work. [Copyright &y& Elsevier]

Abstract: Monolayer zirconia physical vapor deposition (PVD) and sol–gel films on K9 glass substrates were prepared by electron beam evaporation and spin coating methods, respectively. The laser-induced damage threshold (LIDT) of each film was measured. Properties of the films were analyzed using Stanford photo-thermal solutions (SPTS), ellipsometry, atomic force microscopy (AFM) and optical microscopy to study the damage mechanism of films under laser irradiation. The experimental results showed that, compared with the monolayer zirconia sol–gel film, the monolayer zirconia PVD film had larger absorption and smaller porous ratio, and that it had smaller LIDT. The different damage morphologies of films were influenced by their different absorption and microstructure characteristics. The zirconia sol–gel film is more suitable for applications involving high-power lasers. [Copyright &y& Elsevier]

Abstract: Sol–gel single-layer silica acid and base thin films on K9 glass substrates were prepared with the dip-coating method from acid and base catalyzed silica sols, respectively. Laser-induced damage threshold (LIDT) of each film was measured. Properties of the films were analyzed using Stanford photo-thermal solutions (SPTS), ellipsometry, atomic force microscopy (AFM) and optical microscopy to study the damage mechanism of the films under laser irradiation. The experimental results showed that compared with the silica base film, the silica acid film had larger absorption and smaller porous ratio, and it had smaller LIDT. The different damage morphologies of films were influenced by their different absorption and microstructure characteristics. The silica base film is more suitable for applications involving high power lasers. [Copyright &y& Elsevier]

Abstract: Monolayer ZrO2 sol–gel and physical vapor deposition (PVD) films were prepared by spin method and electron beam evaporation method, respectively. Monolayer sol–gel SiO2 films were prepared with the dip-coating method from acid and base catalyzed SiO2 sols, respectively. Some of the SiO2 base films were subsequently treated in saturated ammonia gas for 20h. The laser induced damage threshold (LIDT) of each film was measured. Properties of the films were analyzed by using Stanford photo-thermal solutions (SPTSs), ellipsometer, atomic force microscopy (AFM) and optical microscopy. The experimental results showed that porous ratio is an essential factor to decide the LIDT for sol–gel films, which benefits the pressure exerted on the film or substrate by the moving particle to dissipate. The films with lower thermal absorption and higher porous ratio have higher LIDT. [Copyright &y& Elsevier]

Abstract: Two-layer ZrO2/SiO2 and SiO2/ZrO2 films were deposited on K9 glass substrates by sol–gel dip coating method. X-ray photoelectron spectroscopy (XPS) technique was used to investigate the diffusion of ZrO2/SiO2 and SiO2/ZrO2 films. To explain the difference of diffusion between ZrO2/SiO2 and SiO2/ZrO2 films, porous ratio and surface morphology of monolayer SiO2 and ZrO2 films were analyzed by using ellipsometry and atomic force microscopy (AFM). We found that for the ZrO2/SiO2 films there was a diffusion layer with a certain thickness and the atomic concentrations of Si and Zr changed rapidly; for the SiO2/ZrO2 films, the atomic concentrations of Si and Zr changed relatively slowly, and the ZrO2 layer had diffused through the entire SiO2 layer. The difference of diffusion between ZrO2/SiO2 and SiO2/ZrO2 films was influenced by the microstructure of SiO2 and ZrO2. [Copyright &y& Elsevier]

Abstract: Sol–gel (ZrO2/SiO2)12 ZrO2 films were prepared by spin coating method. The reflectivity spectrum of the films was measured with a Lambda 900 spectrometer. In order to investigate laser-induced damage threshold (LIDT) characteristic of highly reflective films, one-layer ZrO2 and SiO2 films, two-layer ZrO2/SiO2 and SiO2/ZrO2 films were also prepared by spin coating method. LIDT of each film was measured. Damage morphology after laser irradiation was characterized by optical microscopy (Nikon E600K). The experimental results showed that the reflectivity of (ZrO2/SiO2)12 ZrO2 film at 1064nm and 355nm wavelength is 99.7%. The LIDT results decreases as the number of layer of films increases. All the films have similar damage morphology. The experimental results are explained by the different temperature profiles of the films. [Copyright &y& Elsevier]