Ultrafast (<ips-long pulses) cathodes with spatially structured emission are an enabling technology for exciting applications such as free-electron lasers, tabletop coherent x-ray sources, and ultrafast imaging. In this thesis, we explore the scaling down and multiplexing limits of ultrafast photon-triggered field emission cathodes composed of arrays of nano-sharp high-aspectratio silicon pilla...

Here, we demonstrate the simple fabrication of a single-walled carbon nanotube (SWCNT) field emission electrode which shows excellent field emission characteristics and remarkable field emission stability without requiring posttreatment. Chemically functionalized SWCNTs were chemically attached to a silicon substrate. The chemical attachment led to vertical alignment of SWCNTs on the surface. F...

The purpose of this work is to present elements of a design tool for field emission displays using carbon nanotubes as emitters. We use a continuum model to describe the carbon nanotubes and we use a locally one-dimensional approximation to calculate the emission current. We investigate the emission current to voltage characteristic, screening effects and the lateral spread of the emission curr...

We demonstrate hyperbolic metamaterials (HMMs) on a curved surface for an efficient outcoupling of nonradiative modes, which lead to an enhanced spontaneous emission. Those high-wavevector plasmonic modes can propagate along the curved structure and emit into the far field, realizing a directional light emission with maximal fluorescent intensity. Detailed simulations disclose a high Purcell fa...

Enhanced upconversion emission of NaYF(4):Yb,Er nanocrystals with Ag nanowires was observed; the enhancement factor of red emission is larger than that of green emission, and it can be further increased with Ag islands composed of larger Ag particles.

We develop a theory for the total optical secondary emission from a 1D interacting electron system modelled as a Tomonaga-Luttinger liquid. We separate the emission into two parts which may originate in hot luminescence (HL) and Raman Scattering (RS) respectively when we neglect the interference effect. We find a peak around ∆ω = vf |q| in the RS part which does not come from a structure factor...

We present a correlation analysis between the flux ratio of high-energy γ-ray emission to synchrotron emission and the Doppler factor for a sample of EGRET AGNs. The result favors a model that attributes the EGRET emission of AGNs to inverse-Compton scattering on photons external to the jet.

Natural wetlands constitute a major source of methane emission to the atmosphere, accounting for approximately 32 ± 9.4% of the total methane emission. Estimation of methane emission from wetlands at both local and national scale using process-based models would improve our understanding of their contribution to global methane emission. The aim of the study is to estimate the amount of methane ...