Applications of Mössbauer programmable-velocity data acquisition module

A. VEIGA; G. A. PASQUEVICH; P. MENDOZA ZÉLIS; N. MARTÍNEZ; F.H. SÁNCHEZ

Opatija

Conferencia; International Conference on the Application of the Mössbauer Effect; 2013

A. Veiga, G. A. Pasquevich, P. Mendoza Zélis, N. Martínez and F.H. Sánchez.

In this presentation we summarize some of the applications of the Mössbauer effect that can be implemented with a new data acquisition module (MDAQ) developed in our laboratory. This instrument is a programmable-velocity scaler which allows setting dwell-time, channel number and output waveform through a USB port. It can be programmed with almost any of the velocity references useful in Mössbauer experiments, particularly the constant-acceleration and constant-velocity waves, but also ad hoc, custom designed waves. It includes facilities for the operation in programmable-velocity mode, a technique that enables the independent selection of Doppler energy (channel) and acquisition time per channel.Regarding constant-acceleration mode, MDAQ allows to optimize the trajectory by smoothing the vertices of the triangular waveform, therefore achieving a better frequency response of the velocity drive and the electromechanical transducer.  In constant-velocity mode, the module can be setup to measure the Mössbauer effect as a function of an external parameter at a set of selected velocities (e.g. kinetics of crystallization, hyperfine parameters dependence on temperature, etc).More complex experiments can also be performed using the programmable-velocity mode. For example it is possible to measure the Mössbauer effect at a spectral region of interest (ROI) which can be modified as a function of an external parameter such as magnetic field or temperature. Moreover, this instrument allows performing Mössbauer Line Tracking (MLT) experiments. MLT is a methodology designed to record the evolution of a spectral ROI while the external parameter is varied and ROI is repositioned by a tracking algorithm.Two MDAQ modules can be simultaneously used to perform Mössbauer spectroscopy experiments dependent on an external perturbation. Besides typical acquisition of spectra versus a slow varying external parameter, such as temperature, high frequency perturbations (0.1 Hz-100 kHz) can be studied by synchronizing one of the modules with the external perturbation and the other one with the velocity wave. High frequency AC-Magnetic responses and sample vibration studies are some examples of the last type of experiment.