2015 BFY II Abstract Detail Page
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||Electron Spin Resonance: An experiment for perceiving Quantum Physics Intuition
||Quantum physics applies to enormous number of physical phenomena starting fromelementary-particles through the events in atomic scale to all the way to the origin of the early universe. Many modern technologies would be impossible to understand without invoking quantum physics. Almost all the electronic, magnetic, and optoelectronic devices (transistor, laser, LED, MRI, NMR, sensors, etc.) are based on a quantum understanding of the atomic phenomena in solids. However, there is a major problem in the realization of quantum physics as it implies counterintuitive concepts and thoughts. This has led, for example, Niels Bohr (1952) to comment "For those who are not shocked when they first come across quantum theory cannot possibly have understood it" and Richard Feynman (1965) to remark "I think I can safely say that nobody understands quantum mechanics" or Roger Penrose to comment that "theory makes no sense". Electron spin resonance (ESR) is a purely quantum mechanical effect. It relates the interaction of an applied magnetic field to an electron's magnetic moment, which is the manifestation of intrinsic spin. Since the spin of an electron may either be up or down, so may its magnetic moment. The ESR experiment uses a diphenylpicrylhydrazyl (DPPH) sample which has an unpaired electron and its orbital contribution to the magnetic moment is negligible because the molecule moves on a highly delocalized orbit. Since the electron is free, only its spin contributing to the magnetic moment. Thus the Landé g-factor for DPPH is very close to that for a free electron. In this experiment the magnetic field is produced by a pair of Helmholtz coils is series connection with as and dc power supply and photon frequency of 10-50 MHz was used to produce the resonance. This advanced lab experiment allows students to realize the quantum physics concept learned in theory.
University of Puerto Rico, San Juan
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