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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 2847-2855 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The influence of excimer laser irradiation (193 nm, 20 ns pulses and 248 nm, 20 ns and 500 fs pulses) on the structure and morphology of plain and gold-film coated mica surfaces has been investigated for fluences between 8 mJ/c2 and 19 J/cm2. Surfaces treated with laser fluences below the ablation threshold (λ=248 nm) are well suited for controlled growth of metallic films, whereas above-threshold treated samples (λ=193 nm) form roughened surfaces with close-packed arrays of cones. The cone generation can be suppressed by appropriate choice of laser parameters, resulting in the formation of ablation holes with micrometer precision. The same precision can be obtained in ultrathin metallic films without destroying the underlying mica surface. Low-energy electron diffraction is used to monitor laser-induced microscopic changes of the mica surface upon low-fluence irradiation. It is seen that the first step of the ablation process includes reorientation of dipole domains on the surface. Thereafter, scanning electron microscopy reveals melting of the surface and the onset of explosive sputtering processes. Studies of the ablated products by the use of quadrupole mass spectrometry, quartz microbalance, and photoimaging indicate large kinetic energies and a high directionality of the ablated products. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 2201-2205 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Two different highly sensitive and fast but low-cost instruments for fluorescence measurements on nanotiter plates or other high density sample arrays are presented. Both instruments use 635 nm diode lasers for the detection of Cy5 fluorescence. In the first device all cavities of the nanotiter plate are illuminated simultaneously and the fluorescence is detected spatially resolved by a charge-coupled device camera within a few seconds. The second system uses an on-chip microscanner for the sequential illumination of the samples and the fluorescence is detected by a simple photomultiplier tube. Both instruments have originally been developed for environmental analysis by immunochemical labeling but they can also be used for other medical and biological purposes where analyte concentrations have to be determined. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 5458-5468 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A versatile model for ultraviolet (UV) laser ablation of polymers is presented, which is very successfully applied to the calculation of a variety of different properties of this process, including the influence of plume attenuation dynamics. The polymer is described as a system of chromophores with two possible electronic states. The model is based on the combination of photothermal decomposition and photodissociative bond breaking in the electronically excited state. Laser induced chemical modifications are incorporated via different absorption coefficients for the initial and for the modified polymer after absorption of UV light. Dynamic attenuation of the expanding ablation plume and heat conduction are taken into account. The results of the theoretical calculations are compared with the results of three different series of experiments performed with polyimide (PI) and polymethylmethacrylate at the excimer laser wavelength 248 nm and with PI also at 308 nm: (1) Measurement of the ablation rate as a function of fluence for four different pulse durations between 20 and 250 ns; (2) Measurements of the ablation rate as a function of fluence for five different laser irradiation spot radii between 10 and 150 μm, and (3) Time resolved measurement of the dynamic plume attenuation at the ablating laser wavelength as a function of fluence for four different pulse durations between 20 and 250 ns. The model leads to a prediction of etch rates, ablation thresholds, plume attenuation, and surface temperatures during the ablation process, which is in good agreement with the experimental results. The observed increase of the ablation rate with increasing pulse length and with decreasing laser spot size can be explained by the model as a consequence of laser induced modified absorption in combination with the dynamic shielding of the expanding plume. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 2502-2503 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Wavelength-dependent time lags due to group velocity dispersion (GVD)—much larger than estimated and documented thus far—have been determined experimentally for some widely used streak camera objectives. Correction procedures for signals delayed and broadened by group dispersion in streak camera objectives are briefly outlined.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 97 (1993), S. 12296-12301 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Magnetism and Magnetic Materials 46 (1984), S. 40-48 
    ISSN: 0304-8853
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0630
    Keywords: PACS: 42.40; 42.80; 81.60Z
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. Masks for laser processing are generated by laser ablation patterning of dielectric layer systems. The application of these masks for the rapid fabrication of diffractive optical elements (DOEs) is presented. The diffractive optical elements are designed as phase-only elements, assuming an illumination with a plane wave. A continuous phase function is calculated using an iterative Fourier transform algorithm (IFTA). This continuous phase function is reduced to two or four levels by an iterative Fourier quantisation algorithm (IFQA) that is able to include focal power. The fabrication of the DOE is performed in a two-step process. First, a binary amplitude mask (or a set of masks for multi-level DOEs) is made by structured ablation of a highly reflective dielectric coating (HR 248 nm) from a fused silica substrate. This is accomplished by using an ArF excimer laser emitting at 193 nm, a wavelength that is sufficiently absorbed in the HfO2/SiO2-dielectric layer system, leading to precisely ablated mask structures. In the second step, this mask is used in a 4:1 projection configuration to generate a surface profile in a polymer substrate by ablation at 248 nm. The depth modulation can be defined by adjusting laser fluence and pulse number. Examples of DOEs ablated in polycarbonate are shown and their performance is characterised.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0630
    Keywords: PACS: 79.20 Ds; 81.65 Cf; 82.50 Fv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 99-100 (July 2004), p. 65-72 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: Two types of silver-doped glass were used for direct laser recording of 2D and 3Dphotonic crystals. The first contained a diffusion layer (20 microns thick) with embedded silver nanoclusters of 20-nm average radius. 2D and 3D photonic crystals of submicron lattice parameters were fabricated by nanosecond pulsed laser irradiation (l, = 355 nm) using four or five coherent intersecting beams. Under irradiation the clusters absorbing light energy are heated to high temperatures and become mobile due to the formation of liquid shells around them. Adjacent clusters move towards each other and towards the irradiated surface under local temperature gradients, form agglomerates and merge in periodically located "spots" of high light intensity in the interference field. The second type of glass, photosensitive to UV irradiation, contained in the bulk Ag+ and Ce3+ ions. Under UV irradiation excited electrons passed from Ce3+ to Ag+. The Ag atomsbecame neutral and under subsequent heat treatment of the glass at elevated temperatures have a tendency to form nanoclusters, thus “developing” the UV recorded patterns. Using nanosecond pulsed irradiation of 308 nm we have recorded 3D photonic crystals in the bulk of such glass
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Applied Surface Science 46 (1990), S. 279-283 
    ISSN: 0169-4332
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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