Reclaiming Academia from Post-academia

Post-academic science, driven as it is by commercialisation and market forces, is fundamentally at odds with core academic principles. Publicly-funded academics have an obligation to carry out science for the public good, a responsibility which is incompatible with the entrepreneurial ethos increasingly expected of university research by funding agencies

Addicted to the brand: the hypocrisy of a publishing academic

Academics generally recognise that the scholarly publishing business model is flawed, the impact factor does not point to quality, and open access is a good idea. And yet, academics continue to submit their work to the same for-profit journals. Philip Moriarty looks at what is keeping academics from practicing what they preach. Despite many efforts to counter the perception, journal ‘branding’ remains exceptionally important

Nanotechnology: radical new science or plus ça change?

Is a radical nanotechnology involving the construction of macroscopic products via software-directed manipulation of single molecules possible? Are we only a few decades away from a technological utopia where virtually any product may be constructed via molecular manufacturing? These and other similarly provocative questions formed the backdrop for a well-attended debate on nanotechnology held in the University of Nottingham last year (26 August 2005)

Rules of engagement: seven lessons from communicating above and below the line

Social media offers academics a wonderful opportunity to get their message “out there”, to connect with, educate and inform a broad, new online audience. And universities encourage them to do so, to actively market and disseminate their research. Yet although this shouldn’t be a one-way process, the standard mantra for engaging online is: don’t read the comments. Based on his own experiences, and at a time when academics are not always held in the highest regard by the general public, Philip Moriarty has some cautionary advice for those eager to embark on their own online public engagement activities

Atomic resolved material displacement on graphite surfaces by scanning tunnelling microscopy

Atomic scale modifications and subsequent atomic resolution imaging has been achieved on the highly oriented pyrolytic graphite surface in air. Application of short pulse voltages, above a minimum threshold voltage of 3.5 V, across the tunneling gap results in the displacement of a layer or more of atoms to form a hole and create a neighboring mound or ‘‘nanodot’’ from the displaced atoms. We have found a correlation between the hole and ‘‘nanodot’’ volume at the atomic level and observe an asymmetric displacement of material in all cases of feature creation. Nanofeatures as small as four carbon atoms at beta sites have been created. Our experimental observations are consistent with the modification process depending on the gradient in the electric field induced by the rise time of the bias pulse voltage and not the pulse duration. Interesting faceting behavior has also been observed around some hole edges. Tip bias pulsing sometimes induced a tip, and not a surface modification, resulting in a change in the observed tunneling image

Visualizing the 'invisible'

The ability of scientists to image and manipulate matter at the (sub)atomic scale is a result of stunning advances in microscopy. Foremost amongst these was the invention of the scanning probe microscope, which, despite its classification as a microscope, does not rely on optics to generate images. Instead, images are produced via the interaction of an atomically sharp probe with a surface. Here the author considers to what extent those images represent an accurate picture of ‘reality’ at a size regime where quantum physics holds sway, and where the image data can be acquired and manipulated in a variety of ways

A scanning tunnelling microscopy investigation of the interaction of sulphur with semiconductor surfaces

UHV and ambient Scanning Tunnelling Microscopy (STM) have been used to investigate the interaction of sulphur with Si and GaAs (100) and (111) surfaces. The adsoiption of group VI elements on GaAs and other IE-V semiconductor surfaces is well known to passivate the surface, that is, reduce the number of mid-gap surface states. We find that in situ room temperature adsorption of sulphur on both Si(100)-(2xl) and S i(lll)-(7 x 7 ) surfaces, using an electrochemical cell, does not produce an ideal bulk terminated ( lx l ) phase. Thermal desorption of the S overlayer from the Si(100) surface at 325°C leads to the creation of a c(4x4) reconstruction coexisting with the (2x1) reconstruction of the clean surface. High resolution filled- and empty-state images have led to the proposal of a missing dimer defect model for this reconstruction. Following sulfur desorption, at 375°C, from the S i ( l l l ) surface, monolayer deep holes in the (7x7) terraces are clearly visible. Near the edges of these holes, surface atoms are found in either a disordered phase, or forming small areas of other metastable reconstructions. A coalescence of surface vacancies, following defect creation due to sulfur desorption leads to the monolayer etching mechanism. Use of As capped GaAs samples made a characterisation of the clean surface, before sulfur deposition, possible. Room temperature adsorption of sulphur on both GaAs(lOO) and GaAs(l 11)B surfaces leads to the appearance of a ( lx l ) LEED pattern.We find no evidence from STM imaging of a well ordered surface corresponding to this ( lx l) phase. Instead, the ( lx l ) LEED pattern arises through an amorphous S overlayer saturating dangling bonds. Annealing of the S covered GaAs(lOO) surfaces to temperatures above 350°C promotes the formation of a (2x1) reconstruction. STM data, coupled with Auger electron and synchrotron radiation photoelectron core-level spectroscopy studies, suggest that the (2x1) surface most likely consists of both As and S dimers with sulfur also diffusing into the bulk GaAs crystal. For the G aA s ( lll)B surface, after annealing, a similar situation involving both As and S termination, occurs. Fermi level movement due to sulfur adsorption and subsequent annealing on both (100) and ( l l l )B surfaces is discussed. Ambient STM and tunnelling spectroscopy measurements on P2S5/(NH4)2SX treated GaAs(lOO) samples indicate that, with regard to surface homogeneity, they are topographically, chemically and electrically much superior to etched, untreated samples. The subsequent oxidation of these surfaces has been investigated using the real time 3- dimensional imaging capabilities of the STM. Tunnelling spectroscopy results show a considerable reduction in band bending for the passivated surface, with evidence to suggest that the Fermi level is unpinned

Anisotropic Assembly of Colloidal Nanoparticles: Exploiting Substrate Crystallinity

We show that the crystal structure of a substrate can be exploited to drive the anisotropic assembly of colloidal nanoparticles. Pentanethiol-passivated Au particles of approximately 2 nm diameter deposited from toluene onto hydrogen-passivated Si(111) surfaces form linear assemblies (rods) with a narrow width distribution. The rod orientations mirror the substrate symmetry, with a high degree of alignment along principal crystallographic axes of the Si(111) surface. There is a strong preference for anisotropic growth with rod widths substantially more tightly distributed than lengths. Entropic trapping of nanoparticles provides a plausible explanation for the formation of the anisotropic assemblies we observe

Formation routes and structural details of the CaF1 layer on Si(111) from high-resolution noncontact atomic force microscopy data

We investigate the CaF1/Si(111) interface using a combination of high-resolution scanning tunnelling and noncontact atomic force microscopy operated at cryogenic temperature as well as x-ray photoelectron spectroscopy. Submonolayer CaF1 films grown at substrate temperatures between 550 and 600 ◦C on Si(111) surfaces reveal the existence of two island types that are distinguished by their edge topology, nucleation position, measured height, and inner defect structure. Our data suggest a growth model where the two island types are the result of two reaction pathways during CaF1 interface formation. A key difference between these two pathways is identified to arise from the excess species during the growth process, which can be either fluorine or silicon. Structural details as a result of this difference are identified by means of high-resolution noncontact atomic force microscopy and add insights into the growth mode of this heteroepitaxial insulator-on-semiconductor system