Texture of NiGe(Sn) on Ge(100) and its evolution with Sn content

The texture of the Ni monostanogermanide phase on a Ge(100) substrate was evaluated during a solid-state reaction, with a focus on the impact of Sn addition. Complementary X-ray diffraction analyses involving in situ X-ray diffraction, in-plane reciprocal space maps (RSMs) and pole figures were used to that end. A sequential growth of the phases for the Ni/Ge(Sn) system was found. An Ni-rich phase formed first, followed by the NiGe(Sn) phase. The NiGe and NiGe(Sn) layers were polycrystalline with different out-of-plane orientations. The number of out-of-plane diffraction peaks decreased with the Sn content, while the preferred orientation changed. In-plane RSM analyses confirmed these results. Sn addition modified the out-of-plane and in-plane orientations. Pole figure analysis revealed that numerous epitaxial texture components were present for the Ni/Ge system, while Sn addition reduced the number of epitaxial texture components. On the other hand, segregated Sn crystallized with an epitaxial alignment with the Ge substrate underneath.

Light diffraction from a phase grating at oblique incidence in the intermediate diffraction regime

We experimentally characterize the positions of the diffraction maxima of a phase grating on a screen, for laser light at oblique incidence (so-called off-plane diffraction or conical diffraction). We discuss the general case of off-plane diffraction geometries and derive basic equations for the positions of the diffraction maxima, in particular for their angular dependence. In contrast to previously reported work (Jetty et al. in Am J Phys 80:972, 2012), our reasoning is solely based on energy- and momentum conservation. We find good agreement of our theoretical prediction with the experiment. A detailed discussion of the diffraction maxima positions, the number of diffraction orders, and the diffraction efficiencies is provided. We assess the feasibility of an experimental test of the phenomenon for neutron matter waves.

Angle sensitivity testing of equal-period plane diffraction grating fabricated through electron beam lithography line-by-line method

An equal-period plane diffraction grating fabricated through electron beam lithography line-by-line method was designed and applied to the experiment of angle sensitivity testing. The size of the fabricated grating region was [Formula: see text] mm and the period was 1526 nm. The incident light was transmitted via the Y-type fiber to collimator lens fixed on the angle disc, which can be adjusted to change the incident light angle. The diffraction spectra generated by the incident light irradiating the grating surface were collected by the optical spectrum analyzer. In this experiment, the incident light angle was fixed at 25[Formula: see text]. When the spot moved horizontally by 50 mm, the diffraction wavelength was basically unchanged. When the incident light angle was adjusted from 15[Formula: see text] to 31[Formula: see text], the diffraction wavelength was changed from 834.03 nm to 1589.80 nm, the angular sensitivity was 47.508 nm/[Formula: see text], and the linearity was 0.9998.

On the asymptotic properties of a canonical diffraction integral

We introduce and study a new canonical integral, denoted I + − ε , depending on two complex parameters α 1 and α 2 . It arises from the problem of wave diffraction by a quarter-plane and is heuristically constructed to capture the complex field near the tip and edges. We establish some region of analyticity of this integral in C 2 , and derive its rich asymptotic behaviour as | α 1 | and | α 2 | tend to infinity. We also study the decay properties of the function obtained from applying a specific double Cauchy integral operator to this integral. These results allow us to show that this integral shares all of the asymptotic properties expected from the key unknown function G +− arising when the quarter-plane diffraction problem is studied via a two-complex-variables Wiener–Hopf technique (see Assier & Abrahams, SIAM J. Appl. Math. , in press). As a result, the integral I + − ε can be used to mimic the unknown function G +− and to build an efficient ‘educated’ approximation to the quarter-plane problem.