Abstract
To detect the presence of free radicals in materials, a traditional Electron Spin Resonance (ESR) requires repeating setting values of the external magnetic field ( B 0 ) as well as the frequency of microwave signal ( u ) to achieve resonance conditions, and it must be conducted manually. The procedure requires considerable time, so that become ineffective. In this paper, we propose a simple technique to improve the functionality of the traditional ESR by implementation of ramp-type magnetic field and high-speed data acquisition system. In here, we generate ramp-type voltage signal based on PIC16F876 microcontroller as the main device. This signal is converted to the current source by using the circuit of V to I converter, then injected to the Helmholtz coil to generate a ramp-type magnetic field. Some experiments are carried out in order to make validation and determine the performance of the developed system. By the technique, the traditional ESR becomes an automatic ESR-spectrometer and has the capability to identify some kinds of free radicals faster. Keywords: ESR , free-radical , ramp-B .
Highlights
A free radical is atoms or molecules that are unstable and reactive
The identification is usually conducted by using an Electron Spin Resonance (ESR) or sometimes called as an Electron Paramagnetic Resonance (EPR) (Skinner, 2011; Hawkins and Davies, 2014)
We propose a simple technique to improve the functionality of the traditional ESR by implement ramp-type and a wider range of external magnetic field B0
Summary
A free radical is atoms or molecules that are unstable and reactive. The existence of free radicals can be anywhere, including in the foods and others biological tissue. To identify the presence of free radicals in a substances sample, the ESR use Lande-factor (g), which is derived from the relationship between the strength of external magnetic field (B0) and the frequency of microwave ( ) (Serway and Jewett, 2008) In this case, is generated by microwave coil, and B0 is generated by pairs of Helmholtz coils after injected electrical current. On the traditional ESR equipment, the parameter of usually set in several fix frequency values, while parameter of B0 set in sine-modulated fix value In this case, to find out of a free radical in an experiment, the value of as well as B0 should be tuned manually, until resonance condition occurred. The values of “g” (free radicals) can be identified and performed quickly
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