WP1: Instrument development and testing
- Design, fabrication, and assembly of the LMCat set-up
- Preliminary testing and concomitant optimisation of the LMCat set-up
- Transport and installation of the LMCat set-up at ESRF - ID10 beamline
To perform the in situ x-ray and Raman experiments, the first step is to develop customized instrumentation, capable of studying the 2DM formation process on the surface of LMCats. Both in situ experiments need several common features: gas mixing and analyzing systems, LMCat reactor, heating and cooling systems, etc.
To guarantee the reproducibility of exact 2DM growth conditions for Raman and x-ray experiments, and also from a financial point-of-view, both techniques will be integrated in one LMCat set-up. For the design and fabrication of such a novel instrument, several technical issues need to be addressed:
- The surface of the liquid metal should be as undisturbed as possible. This is especially important for x-ray measurements where a precise definition of the incident beam on the liquid surface is needed. One potential source of liquid-surface disturbance is the convective currents in the LMCat. Therefore, the heating mechanism inside the reactor has to be designed to minimize these currents at the x-ray beam or Raman laser incident points.
- Rapid evaporation of the atoms from the LMCat surface can contribute to surface disturbance and the evaporated atoms can deposit on reactor windows and disturb the x-ray/Raman measurements. To suppress the evaporation, a noble gas containing the 2DM formation precursor mixture (e.g. CH4, H2) can be used to flow through the reactor. The presence of noble gas on the molten surface will 1) suppress the evaporation of the LMCat, 2) slow down the diffusion of evaporated metal toward the windows, while 3) evaporated atoms will be swept away by the flow of the carrier gas through the reactor before they can reach the optical windows.