# Physics Of Q-Dots Lab Report

Quantum dots (Q-Dots) is very small semiconductor particles that means it can be either conductors or resist electricity depending on the temperature and purity of the semiconductor. Q-dots range in size from 2-10 nm, so because of their small size, quantum mechanics governs the physics of the particles. The synthesis Q-Dots were first studied in 1982 by Efros and Ekimov, and then many developments have reported the synthesis of semiconductor nanoparticles.1 Q-Dots have unique properties, which is emitting color depending on the size not its materials. For big particles Q-Dots have the large wavelength and the small frequency, and the small particles Q-Dots have the low wavelength and high frequency. This is because of the

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The optical bandgap (EQD) can be assessed using Tauc Relation equation (2). (αhυ)2 = f(R) hυ = B (hυ - EQD )n (2) where B is proportional constant (often negligible), hv is photon energy, EQD is bandgap energy, n based on the transition type (n = 1/2 for direct allowed transitions), and α is absorption coefficient. Kubelka-Munk Equation (3): approximation of α .5 f(R)=(1-R)2/R=k/s (3)

Where R is reflectance, k is the molar absorption coefficient, and is scattering coefficient. However, this method requires solid sample state analysis, which is not performed in this study. Therefore, trying to attempt a double derivative of the absorption by plotting the points and found a polynomial (third degree) trend line, performed a single and double derivative to determine the changes slopes. The first derivative determines speed of slope change: onset wavelength of peak and theory: second derivative finds acceleration of change: at y = 0, x = onset wavelength. In the first trial, the instrument zeroed using DI water in both cuvettes and 2-5mg of sample diluted to various volumes in DI water using volumetric flasks, and this was used as reference for all analyses. In the second trial, using RO water, and this was used as reference for all analyses. However, all these analyses that used different water showed the same results. %Transmittance and % Reflectance were also collected but not