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Experiments show that the elastic constants of single-crystal nitride films produced on substrates of single-crystal cubic-symmetric magnesium oxide (MgO) are of the cubic symmetry of c11, c12 and c44. Line focus acoustic microscopy was used to study surface acoustic wave (SAW) dispersion curves from single crystal films of NbN, TiN and VN. The Rayleigh wave strengths measured from the elastic constants concurred with earlier reports.

A study was conducted on the elastic properties of TiN/(VxNb1-x)N superlattices. Brillouin scattering was used to measure the single-crystal lattice-matched superlattices. Results show that surface wave velocities are independent of superlattice wavelength and thus indicates the absence of any anomaly in the c44 elastic constant. Further observations also showed that the average lattice spacing does not vary with wavelength. The results of the study provided preliminary evidence that elastic anomalies do not cause large hardness enhancements in nitride superlattices.

In linear arrays of optically probed bismuth-doped iron garnet films, the Faraday rotation signal produced by an external magnetic field is a complex function of film shapes, stacking geometries, optical path length, and insertion losses. Studies of arrayed responsivities under various configurations reveal a proximity coupling effect between ferromagnetic domains of adjacent films, which enhances Faraday rotation by minimizing demagnetization effects at the interfaces. The effect is activated by matching ferromagnetic domain patterns in adjacent films and has resulted in over a twofold improvement in detection sensitivities when the arrays were configured as polarimetric magneto-optic sensors. [ABSTRACT FROM AUTHOR]

From the early days of free-electron lasers (FELs), the idea of lasing at wavelengths where gain media had not previously existed was one of the most attractive aspects of these devices. The spectral region in the soft X-ray was both inviting, due to the exciting physics one could do with such a source, and challenging, due to the need for a very bright electron beam (high charge density), very high gain to overcome cavity losses, and the cost of providing all this at very high electron beam energies with high-duty-cycle electron beams. Electron beam brightness is defined as the ratio of the peak current to the product of the horizontal and vertical normalized emittances. The normalized electron beam emittance is the product of the rms transverse size and momentum spread. High gain is usually obtained using a very long undulator, which requires a very small energy spread in addition to the small transverse emittance. Electron beams in the 1970s generally provided either low peak current or large energy spread and very low charge density. Even the VUV spectral range was considered too difficult for the accelerators and optics available then. Early FELs therefore operated in the infrared range. FEL oscillators were eventually pushed into the visible and ultraviolet but could not push into the VUV due to either low gain or poor mirror reflectivity. [ABSTRACT FROM AUTHOR]

In bismuth-doped iron garnets, diamagnetic dilution of Fe with Ga is a well-known method to increase the Faraday rotation response under externally applied magnetic fields. It is found, however, that while this method improves responsivity at larger field strengths, the responsivity under smaller fields (which are more typical in sensing applications) is generally unaffected by Ga doping. The data indicate that the low-field responsivity is limited by anomalous pinning effects in the rotational magnetization process of the ferromagnetic domains. To overcome this, a magnetic bias- ing technique was developed, which enhances responsivity by activating Barkhausen steps in the films to free the domains from their pinning sites. [ABSTRACT FROM AUTHOR]

Titanium substrates were irradiated in pure nitrogen gas by means of a free-electron laser. The treatment resulted in the formation of d-TiNx coatings, with surface stoichiometry x˜1 and thickness of about 15 µm. Under specific experimental conditions the nitride phase had a remarkable crystallographic texture with the d-TiNx(200) planes parallel to the irradiated surface, and well aligned dendrites growing normal to the surface. The mechanism of the dendritic alignment and the origin of the texture correlate with the existence of a solidification front starting at the surface, which is very peculiar for laser surface treatments. This phenomenon is explained with the help of numerical simulations. [ABSTRACT FROM AUTHOR]

Abstract: The design and operating principles of a new type of surface electromagnetic wave sensor are described and demonstrated. The method of operation of this device is similar to surface plasmon sensors except that the surface-active material—a metal film in the case of surface plasmon sensors—is replaced by a one-dimensional photonic band-gap array. The advantages of using a photonic band-gap material instead of a metal film include enhanced sensitivity, physical, and chemical robustness, and the ability to engineer the optical response of the surface active layer to create a device that operates at any optical wavelength. Experimental results are presented that illustrate sensing action by measuring the shift in the surface mode coupling angle with surface loading. [Copyright &y& Elsevier]

Bismuth doped iron garnet films were studied in arrayed structures to improve sensitivity in polarimetric magnetic field sensors. The sensitivity gained from the arrayed configuration was found to depend on the ferromagnetic domain geometry of the films. Under small, externally applied fields, films with planar anisotropy yielded an optical modulation depth which increased linearly with the number of crystals in the array. In films with perpendicular anisotropy, linearity and sensitivity were obstructed by a mechanism of optical polarization incoherence which was found to be generated within the magnetic domains. Our results indicate that optimal sensitivity in arrayed configurations requires planar anisotropies, or a direction of laser propagation that is perpendicular to the local domain magnetization. [ABSTRACT FROM AUTHOR]

This column describes the nonproprietary software Talker, used to adapt screening instruments to audio computer-assisted self-interviewing (ACASI) systems for low-literacy populations and other populations. Talker supports ease of programming, multiple languages, on-site scoring, and the ability to update a central research database. Key features include highly readable text display, audio presentation of questions and audio prompting of answers, and optional touch screen input. The scripting language for adapting instruments is briefly described as well as two studies in which respondents provided positive feedback on its use. [ABSTRACT FROM AUTHOR]

A promethium (Pm3+) laser has been demonstrated for the first time. Trivalent promethium 147 doped into a lead-indium-phosphate glass étalon was used to produce room-temperature four-level laser emission at wavelengths of 933 and 1098 nm. Spectroscopic and kinetic measurements have shown that Pm3+ is similar to Nd3+ as a laser active ion. [ABSTRACT FROM AUTHOR]

Examines the structure and hardness of epitaxial V[sub 0.6]Nb[sub 0.4]N/NbN superlattices. Deposition of the superlattices on magnesium oxide(100) by reactive sputtering; Assessment of the superlattice composition modulation; Measurement of titanium nitride/niobium nitride samples.