Photoconductivity on K-feldspar

Abstract

In the development of most phenomenological models used to explain the infrared excited luminescence, a major assumption is usually made in the degree of freedom the excited charge has. One of the two extremes is normally assumed: charge is free to move anywhere over the whole crystal, or it is confined close to the trap and the centers immediately adjacent to it. Determining which of these extremes is more reasonable is difficult to do on the basis of the temporal behavior of the luminescence intensity alone. However, this assumption has important consequences for the understanding of the dynamics of the luminescence process because of the difference in the number of recombination and trapping centers available to the excited charge. Additional experimental evidence was thus sought on this aspect of charge movement. One such experiment is the detection of photoconductivity in which an electrical current is measured during optical excitation or shortly there-after. In this paper, the details of photoconductivity experiments on K crystal are presented. Photoconductivity measurements were inconclusive as to whether or not there was a current flowing during the 850 nm excitation of a feldspar sample. However, there was a clear current when exciting the same sample with 515 nm light, but there was a complex relationship between the magnitude of the current and the number of emission photons counted. A model was developed to explain the photoconductivity results where electrons migrate through the conduction band aided by thermal excitation and tunneling.

Design and Simulation of an Inverter Drive System with a Display for a Renewable Energy System in the Rural Isolated Communities of Uganda

“…The buffer circuit consisting of a small resistor, capacitor, inductor connected in parallel and a switch is inserted into the DC-AC link to absorb the current and voltage ripples and prevent them from being applied to the next level. This is done by using a capacitor with value twice the frequency of the power supply and system [7] [26]. Note that the buffer circuit is also used as a snubber circuit for the purpose of circuit protection which is further used as a safety mechanism for excess current and voltage that would damage the entire circuit.…”

Investigation into radioactivity levels in soil samples from wheat cultivation sites in Kapchorwa district Uganda

“…Since the Earth's origin, naturally occurring radioactivity has been a part of our environment [1][2][3]. Commonly found in rocks and soils are radioactive elements like uranium ( 238 U), thorium ( 232 Th), and potassium ( 40 K) [4][5][6], which all contribute to background radiation levels [7][8][9]. However, some human activities particularly poor farming methods like overusing fertilizer, might make it worse for these radionuclides to build up in the soil [10][11][12], which raises questions about possible health risk from radiation exposure.…”