Conjugated polyelectrolyte nano field emission adlayers.

Here we report on a straightforward and rapid means of enhancing the field electron emission performance of nascent vertically aligned multi-walled carbon nanotubes by introducing a polar zwitterionic conjugated polyelectrolyte adlayer at the vacuum-emitter interface. We attribute the observed 66% decrease in turn-on electric field to the augmented emitter micro-morphology and shifted surface band structure. The composite emitters can be optically modulated by exploiting the absorption cross-section of the solution cast adlayer, which increases the local carrier concentration which broadens the effective electrostatic shape of the emitter during optical excitation. Assessment via scanning anode field emission microscopy reveals a 25% improvement in DC time stability, a significant reduction in long-term hysteresis shift, and a threefold increase in bandwidth during pulsed mode operation.Oppenheimer TrustThis is the final version of the article. It first appeared from the Royal Society of Chemistry via http://dx.doi.org/10.1039/c6nh00071

Suppressed Hysteretic Field Emission from Polymer Encapsulated Silver Nanowires

Suppression of the hysteretic electron emission in one-dimensional nanomaterial-based electron sources remains a critical barrier preventing their wide scale adoption in various vacuum electronics applications. Here, we report on the suppressed hysteretic performance, and its photo-dependence from conformal poly-vinylpyrrolidone encapsulated percolative Ag nanowire-based electron sources.This work was supported in part by the Oppenheimer Research Trust, Cambridge University, and an Impact Acceleration grant from the Engineering and Physical Sciences Research Council

Comparative 3D QSAR study on β1-, β2-, and β3-adrenoceptor agonists

A quantitative structure–activity relationship study of tryptamine-based derivatives of β1-, β2-, and β3-adrenoceptor agonists was conducted using comparative molecular field analysis (CoMFA). Correlation coefficients (cross-validated r2) of 0.578, 0.595, and 0.558 were obtained for the three subtypes, respectively, in three different CoMFA models. All three CoMFA models have different steric and electrostatic contributions, implying different requirements inside the binding cavity. The CoMFA coefficient contour plots of the three models and comparisons among these plots provide clues regarding the main chemical features responsible for the biological activity variations and also result in predictions which correlate very well with the observed biological activity. Based on the analysis, a summary regeospecific description of the requirements for improving β-adrenoceptor subtype selectivity is given

Nanomaterial-based x-ray sources

Following the recent global excitement and investment in the emerging, and rapidly growing, classes of one and two-dimensional nanomaterials, we here present a perspective on one of the viable applications of such materials: field electron emission based x-ray sources. These devices, which have a notable history in medicine, security, industry and research, to date have almost exclusively incorporated thermionic electron sources. Since the middle of the last century, field emission based cathodes were demonstrated, but it is only recently that they have become practicable. We outline some of the technological achievements of the past two decades, and describe a number of the seminal contributions. We explore the foremost market hurdles hindering their roll-out and broader industrial adoption and summarise the recent progress in miniaturised, pulsed and multi-source devices

High performance field emitters

The field electron emission performance of bulk, 1D, and 2D nanomaterials is here empirically compared in the largest metal-analysis of its type. No clear trends are noted between the turn-on electric field and maximum current density as a function of emitter work function, while a more pronounced correlation with the emitters dimensionality is noted. The turn-on field is found to be twice as large for bulk materials compared to 1D and 2D materials, empirically confirming the wider communities view that high aspect ratios, and highly perturbed surface morphologies allow for enhanced field electron emitters

CNTs and graphene for X-ray systems

Carbon based materials have been investigated as possible field emission sources for a plethora of applcations. This paper will describe our recent work on the design, growth and optimisation of CNTs for apptcation in pulsed x-ray sources and end with our recent work on the use of Graphene

Conjugated polyelectrolyte nano field emission adlayers

Here we report on a straightforward and rapid means of enhancing the field electron emission performance of nascent vertically aligned multi-walled carbon nanotubes by introducing a polar zwitterionic conjugated polyelectrolyte adlayer at the vacuum-emitter interface. We attribute the observed 66% decrease in turn-on electric field to the augmented emitter micro-morphology and shifted surface band structure. The composite emitters can be optically modulated by exploiting the absorption cross-section of the solution cast adlayer, which increases the local carrier concentration which broadens the effective electrostatic shape of the emitter during optical excitation. Assessment via scanning anode field emission microscopy reveals a 25% improvement in DC time stability, a significant reduction in long-term hysteresis shift, and a threefold increase in bandwidth during pulsed mode operation

Suppressed Hysteretic Field Emission from Polymer Encapsulated Silver Nanowires

Suppression of the hysteretic electron emission in one-dimensional nanomaterial-based electron sources remains a critical barrier preventing their wide scale adoption in various vacuum electronics applications. Here, we report on the suppressed hysteretic performance, and its photo-dependence from conformal poly-vinylpyrrolidone encapsulated percolative Ag nanowire-based electron sources

Suppressed Hysteretic Field Emission from Polymer Encapsulated Silver Nanowires

Suppression of the hysteretic electron emission in one-dimensional nanomaterial-based electron sources remains a critical barrier preventing their wide scale adoption in various vacuum electronics applications. Here, we report on the suppressed hysteretic performance, and its photo-dependence from conformal poly-vinylpyrrolidone encapsulated percolative Ag nanowire-based electron sources