Applications of Mössbauer programmable-velocity data acquisition module

A. VEIGAA, G.A. PASQUEVICHA, P. MENDOZA ZÉLISA, N. MARTÍNEZ AND F.H. SÁNCHEZ

Opátija

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

IBAME

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 [1]. 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 constantvelocity 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 [1]. 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) [2]. 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 [3,4]. 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 [5]. 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 ACMagnetic responses [2] and sample vibration studies [6] are some examples of the last type of experiment. [1] A. Veiga et al., Hyperfine Interact. 202 (2011) 107. [2] G.A. Pasquevich et al., Phys. B Condens. Matter 384 (2006) 348. [3] P. Mendoza Zélis et al., Hyperfine Interact. 195 (2010) 161. [4] P. Mendoza Zélis et al., J. Phys. Conf. Ser. 217 (2010) 012017. [5] A. Veiga et al., Hyperfine Interact. 118 (2009) 137. [6] G.A. Pasquevich et al., Hyperfine Interact. (in press, doi: 10.1007/s10751-013-0844-3)