PROTEST AMERICAN ENGLISH INFLUENCE OR PROTEST AGAINST IT? CHANGING PREPOSITIONS IN NIGERIAN TWITTER ENGLISH

According to Alo and Mesthrie (2008), Nigerian English (NigE) becomes increasingly more influenced by American English (AmE), due to contact with American-trained professionals among other factors (cf. Gut 2008, Jowitt 1991). The online micro-blogging service Twitter offers potential communication with a vast number of English natives around the globe, using English in a vernacular usage domain, among other domains (or genres such as a news tweet vs a private tweet). With its foundation in 2006, Twitter is a new communication technology, which may indicate that it is used predominantly by “younger” urban people, and which may influence linguistic choices. The question I attempt to answer is whether Twitter influences NigE such that the British English (BrE) heritage of the country is contested by AmE influence. In this paper, I focus on the usage of prepositions and orthographic realizations of lemmata ending in -o(u)r, which can be categorized as BrE and AmE origin, respectively, in a NigE Twitter Corpus compiled in 2016-17 (13 mill. words). These features’ frequencies are contrasted with those of the Nigerian component of GloWbE (Davies 2013). Results from chi-squared tests suggest that AmE prepositions increasingly enter NigE Twitter discourse. Differences in spelling tend towards American English, but are not statistically significant. The only exception is the lemma labour, which is more often used in its British English spelling variant (χ2 = 26.30; df = 1; p one-tailed < 0.001)

Interface dipoles of organic molecules on Ag(111) in hybrid density-functional theory

We investigate the molecular acceptors 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA), 2,3,5,6-tetra uoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), and 4,5,9,10-pyrenetetraone (PYTON) on Ag(111) using densityfunctional theory. For two groups of the HSE(\alpha, \omega) family of exchange-correlation functionals (\omega = 0 and \omega = 0.2\AA) we study the isolated components as well as the combined systems as a function of the amount of exact-exchange (\alpha). We find that hybrid functionals favour electron transfer to the adsorbate. Comparing to experimental work-function data, we report for (\alpha) ca. 0.25 a notable but small improvement over (semi)local functionals for the interface dipole. Although Kohn-Sham eigenvalues are only approximate representations of ionization energies, incidentally, at this value also the density of states agrees well with the photoelectron spectra. However, increasing (\alpha) to values for which the energy of the lowest unoccupied molecular orbital matches the experimental electron affinity in the gas phase worsens both the interface dipole and the density of states. Our results imply that semi-local DFT calculations may often be adequate for conjugated organic molecules on metal surfaces and that the much more computationally demanding hybrid functionals yield only small improvements.Comment: submitted to New Journal of Physics (2013). More information can be found at http://th.fhi-berlin.mpg.de/site/index.php?n=Publications.Publication

Antenna-enhanced Optoelectronic Probing of Carbon Nanotubes

We report on the first antenna-enhanced optoelectronic microscopy studies on nanoscale devices. By coupling the emission and excitation to a scanning optical antenna, we are able to locally enhance the electroluminescence and photocurrent along a carbon nanotube device. We show that the emission source of the electroluminescence can be point-like with a spatial extension below 20 nm. Topographic and antenna-enhanced photocurrent measurements reveal that the emission takes place at the location of highest local electric field indicating that the mechanism behind the emission is the radiative decay of excitons created via impact excitation