Evaluation of Mössbauer spectra linearization methods

Abstract

Mössbauer spectra linearity is a critical parameter for Mössbauer spectrometer accuracy determination. This paper deals with comparison of various Mössbauer spectra linearizing methods. First method uses sine velocity waveform followed by linearization process. Next method introduces additional modulation based on the velocity error signal measured by laser vibrometer. Last evaluated method combines both. It uses the velocity error signal measured by laser vibrometer as linearization function. Custom Mössbauer spectrometer was constructed for the linearization evaluation. The spectrometer velocity driving system is based on the digital PID controller concept deployed in the FPGA chip of CompactRIO real-time hardware device. The obtained data demonstrate that all evaluated methods increases the linearity of spectra in a wider frequency and amplitude range of a drive signal in comparison with those measured using a traditional measurement method. Highest linearization effect has the method using sine velocity waveform, as generally harmonic movement is natural for used double loudspeaker type velocity transducers. Results show the possibility to use proposed linearization methods for higher velocity ranges using standard transducers and shows potential to be applied in the simple control of transducers without PID regulation or in piezoelectric transducer applications.