Position paper on the potential of inadvertent weather modification of the Florida peninsula resulting from the stabilized ground cloud

Based on the climatology of the Florida Peninsula, we assessed the risk for weather modification. Certain weather situations warrant launch rescheduling because of the risk of possible impact on hurricanes, hail formation and lightning activity, strong wind developments, and intensification of high rainfall rates. The cumulative effects of 40 launches per year on weather modification were found to be insignificant

Position paper on the potential of inadvertent weather modification of the Florida Peninsula resulting from neutralization of space shuttle solid rocket booster exhaust clouds

A concept of injecting compounds into the exhaust cloud was proposed to neutralize the acidic nature of the low-level stabilized ground cloud (SGC) was studied. The potential Inadvertent Weather Modification caused by exhaust cloud characteristics from three hours to seven days after launch was studied. Possible effects of the neutralized SGC in warm and cloud precipitation processes were discussed. Based on a detailed climatology of the Florida Peninsula, the risk for weather modification under a variety of weather situations was assessed

Lead oxides for photovoltaics

This thesis investigates lead oxides as photovoltaic materials. Vacuum deposition methods and ex-situ annealing are used to produce different stoichiometries of lead oxide. The relationship between structure and the optoelectronic properties is then investigated. Following this, a number of photovoltaic devices are prototyped and a Kelvin probe used to determine and understand the band structure of devices. Thin films of PbO produced via air annealing of thermally evaporated lead consist of a mixture of two phases, orthorhombic and tetragonal, that determine the materials properties and effectiveness as absorber layer in a Schottky device. Films of higher tetragonal content are more photoactive, showing lower series resistance. Kelvin probe reveals that with an increasing work function of the PbO with increasing duration of the annealing, the Schottky barrier between PbO and Al increases, which results in a higher VOC. This trend is inverted when the Fermi level of PbO drops below that of ITO, creating an opposing junction. Reactively sputtered PbO2 films are highly conductive degenerate semiconductors. Increasing oxygen flow rate during deposition leads to increased resistivity and decreased mobility, resulting from a decrease in grain size. Alongside this an increase in carrier concentration is observed as the material gets less ordered at higher oxygen flow rates, which results in an increase in Fermi level. Due to its high conductivity the material is not photoactive, and the high work function between -5.6 and -5.8 eV does not allow the formation of a Schottky junction or a p-n junction with the evaporated p- type PbO. Post deposition annealing of the sputtered films leads to the formation of the more resistive Pb3O4 phase. This material shows lower carrier concentration and mobility, however, work functions are similarly high. The changes induced by the heat treatment are not substantial enough to be able to create a junction between the as-deposited and the annealed material, as is revealed by Kelvin probe and Hall Effect measurements. Heterojunctions between P3HT and Pb3O4 were made to test predictions made by KP measurements. A heat treatment on P3HT improved its electronic properties and raised the Fermi level, resulting in the transformation of a diode in to a photovoltaic device and a decrease in dark current.This thesis is not currently available in ORA

Cs[Tf2N]: a second polymorph with a layered structure

The structural determination of the ionic liquid, caesium bis[(trifluoromethyl)sulfonyl]imide or poly[[μ4-bis[(trifluoromethyl)sulfonyl]imido]caesium(I)], Cs[N(SO2CF3)2] or Cs[Tf2N], reveals a second polymorph that also crystallizes in a layer structure possessing monoclinic P21/c symmetry at 120 K instead of C2/c for the known polymorph [Xue et al. (2002). Solid State Sci. 4, 1535–1545]. The caesium ions in the cationic layers are coordinated by the sulfonyl groups of the bistriflimide molecules from anion layers while the trifluoromethyl groups are oriented in the opposite direction, forming a non-polar surface separating the layers. The layer direction is (100)