The Lyddane-Sachs-Teller relationship for polar vibrations in materials with monoclinic and triclinic crystal systems

A generalization of the Lyddane-Sachs-Teller relation is presented for polar vibrations in materials with monoclinic and triclinic crystal systems. The generalization is derived from an eigen displacement vector summation approach, which is equivalent to the microscopic Born-Huang description of polar lattice vibrations. An expression for a general oscillator strength is also described for materials with monoclinic and triclinic crystal systems. A generalized factorized dielectric response function characteristic for monoclinic and triclinic materials is proposed. The generalized Lyddane-Sachs-Teller relation is found valid for monoclinic $\beta$-Ga$_2$O$_3$, where accurate experimental data became available recently from a comprehensive generalized ellipsometry investigation. Data for triclinic crystal systems can be measured by generalized ellipsometry as well, and are anticipated to become available soon and results can be compared with the generalized relations presented hereComment: 5 pages, 1 figur

TERAHERTZ RESONATOR

A tunable terahertz resonator includes a semiconductor Substrate and a metal layer contacting a surface of the semiconductor substrate. A depletion layer is formed in the semiconductor substrate near an interface between the metal layer and the semiconductor Substrate. A chiral nanostructure is coupled to the substrate or the metal layer, the chiral nanostructure including a conducting or semiconducting material and having an inductance. A bias circuit applies a bias Voltage across the metal layer and the semiconductor Substrate to control a capacitance of a tunable capacitor that includes the depletion layer. The chiral nanostructure and the tunable capacitor form a tunable resonant circuit. The tunable terahertz resonator can be used in a terahertz radiation emitter or receiver

Fan motives for interacting on social media – the example of the International Table Tennis Federation and Facebook

Social media has become an important tool for sport organisations to interact with fans. In particular for sports that have smaller marketing budgets and that do not receive mainstream media coverage on a daily basis, social media platforms provide unique communication and marketing opportunities to overcome such challenges. This study investigates the motives of fans to communicate on the Facebook page of the International Table Tennis Federation (ITTF). It is the first study that focuses on the use of social media in the context of an international sport federation. Knowledge about the gratifications sought by fans while interacting on social media is important for organisations to develop more customised online content, as this may help to reach further goals such as maintaining public interest, reinforcing brand awareness or developing closer relationships with stakeholders. We extend the academic understanding of sport fans’ motives in the context of social media and derive implications that can be relevant for managers of (niche) sport organisations with limited financial and personal resources

Tunable plasmonic resonances in highly porous nano-bamboo Si-Au superlattice-type thin films

We report on fabrication of spatially-coherent columnar plasmonic nanostructure superlattice-type thin films with high porosity and strong optical anisotropy using glancing angle deposition. Subsequent and repeated depositions of silicon and gold lead to nanometer-dimension subcolumns with controlled lengths. The superlattice-type columns resemble bamboo structures where smaller column sections of gold form junctions sandwiched between larger silicon column sections ("nano-bamboo"). We perform generalized spectroscopic ellipsometry measurements and finite element method computations to elucidate the strongly anisotropic optical properties of the highly-porous nano-bamboo structures. The occurrence of a strongly localized plasmonic mode with displacement pattern reminiscent of a dark quadrupole mode is observed in the vicinity of the gold subcolumns. We demonstrate tuning of this quadrupole-like mode frequency within the near-infrared spectral range by varying the geometry of the nano-bamboo structure. In addition, coupled-plasmon-like and inter-band transition-like modes occur in the visible and ultra-violet spectral regions, respectively. We elucidate an example for the potential use of the nano-bamboo structures as a highly porous plasmonic sensor with optical read out sensitivity to few parts-per-million solvent levels in water

Optical anisotropy of porous polymer film with inverse slanted nanocolumnar structure revealed via generalized spectroscopic ellipsometry

We use generalized spectroscopic ellipsometry to characterize the biaxial optical properties of porous polymer and slanted nanocolumnar template thin films. The porous polymer with inverse columnar structure was prepared via infiltrating polymer into the voids of the slanted nanocolumnar film and selectively removing the column material (cobalt). The anisotropic Bruggeman effective medium approximation was employed to analyze the ellipsometry data of the porous polymer film and nanocolumnar template. The classification and structure of optical anisotropy are found to be identical for both samples. The interchangeable optical behaviors between two complementary structures are attributed to the equivalency in their anisotropic polarizabilities

Legal Issues of Personalized eCommerce Applications

Most e-commerce applications require the collection and storing of information about customers. As a consequence, the performed transactions involve legal issues. For two years, the authors have been involved in a project, which studies the potentials of personalization of e-commerce systems from the particular angle of SMEs. The paper picks up a couple of scenarios that many e-commerce vendors face when implementing personalization on their Web sites. The specific focus of the discussion is the legal use of costumer profiles for e-commerce applications. Since most legal issues are difficult to understand for non-lawyers the paper makes use of a case study, which shows explicitly what ecommerce vendors need to keep in mind when implementing personalization on their Web sites