No abstract

No abstract

A tunable ultraviolet (UV) laser was used to irradiate the screen-printed carbon nanotube (CNT) samples in air and in high vacuum. UV laser lights with wavelengths of 349 and 266 nm from a tunable laser were used with average energy densities of 20.3, 10.2, and 2.25 mJ/cm2, respectively, with different irradiation times. The field emission characteristics of the CNT cathodes irradiated in air were drastically improved, whereas those of the samples irradiated in vacuum were slightly improved. Irradiation by a 266 nm laser light resulted in more obvious improvement in the emission characteristics than that by 349 nm. The maximum emission current density at an applied electric field of 6.2 V /μm at an energy density of 20.3 mJ/cm2 increased from 0.006 to 20.15 mA/cm2 after laser irradiation with a wavelength of 266 nn, and the turn-on field decreased from 3.7 to 1.2 V/μm.

We show that the 3D charged Banados-Teitelboim-Zanelli (BTZ) black hole solution interpolates between two different 2D AdS spacetimes: a near-extremal, nearhorizon AdS 2 geometry with constant dilaton and U(1) field and an asymptotic AdS 2 geometry with a linear dilaton. Thus, the charged BTZ black hole can be considered as interpolating between the two different formulations proposed until now for AdS 2 quantum gravity. In both cases the theory is the chiral half of a 2D CFT and describes, respectively, Brown-Hennaux-like boundary deformations and near-horizon excitations. The central charge c as of the asymptotic CFT is determined by 3D Newton constant G and the AdS length l, c as = 3l/G, whereas that of the near-horizon CFT also depends on the U(1) charge Q, c nh ∝ lQ/ √ G.