ABSTRACT
Hafnium dioxide thin films were deposited by reactive electron-beam evaporation at six different substrate temperatures on fused-silica substrates. During the depositions, the scattering of light caused by the growth of defects in the films was recorded with in situ total internal reflection microscopy. After deposition the films were analyzed by angle-resolved scatterometery, spectrophotometric measurement of film reflectance and transmittance, atomic force microscopy, and x-ray diffraction. We explore the effects of film defect formation on film optical properties and film surface topography using these data.
ABSTRACT
The relationship of light scatter by a thin film to thin-film morphology is examined. Light scatter by reactively evaporated ZrO(2) thin films is analyzed by using in situ total internal reflection microscopy and angle-resolved scatterometry. Film crystal structure is analyzed by transmission electron microscopy and x-ray diffraction. Relations between film crystal structure and film scatter are established by using this information. Surface topography is analyzed by the use of scanning force microscopy. Results of a spectrophotometric determination of the film refractive index are reported. The film scatter is found to be sensitive to the crystal phase of the film, which is a function of substrate deposition temperature. A simple method of separating bulk from surface scatter is described.
ABSTRACT
Ion-beam-figuring techniques have been applied to fabricate high-power transmission gratings for use in photoacoustic spectroscopy. A thin-film assembly of SiO(2) and TiO(2) layers on an SiO(2) substrate provides a high-reflecting characteristic at a desired wavelength. With standard photolithographic techniques a grating pattern is developed on the surface of the assembly then ion etched with ion-beam-figuring techniques. These gratings exhibit an increased factor of 25 in acoustic signal levels when compared with previously used chemical-etched silicon gratings. This increase was obtained owing to higher transmission, less thermal distortion, and the ability to withstand higher incident power levels.
ABSTRACT
The sensitivity of surface-acoustic-wave detection is extended by several orders of magnitude to a surface-specific absorbance of alphal ~ 10(-9) for a power density of 1 GW/cm(2) using a narrow-bandwidth interdigitated surface-acousticwave detector and an optical irradiation pattern to provide a matched acoustic signal. Major advantages include narrow-bandwidth detection and a large irradiated area that permits more optical energy on the sample. A rapid, nondestructive, reproducible liquid-bonding technique, which permits the extension of these measurements to a wide variety of samples, is demonstrated. Results for AlN and ZrO(2) films (alphal ~ 10(-4)) and fused-silica substrates (alphal ~ 10(-6)-10(-7)) are reported.
ABSTRACT
To analyze the mechanism of the cerebral vasodilator effect of ketamine in anesthetized rabbits, we measured the internal carotid blood flow with an electromagnetic flowmeter, the arterial pressure, intracranial pressure, end-tidal CO2, and the electroencephalogram. Ketamine injection (1 mg/kg) induced a significant cerebral vasodilatation that was blocked by scopolamine, a cholinergic antagonist. In contrast, the increase in cerebral blood flow after ketamine was additive to the cerebral vasodilator actions of inhaled CO2 and of physostigmine infusion, two procedures that activate cholinergic mechanisms. These observations suggest that in rabbits, ketamine activates a cholinergic cerebral vasodilator system.
