Contact LISA: Fridolin Kwabia Tchana

PI: Fridolin Kwabia Tchana, L. Manceron, P.Roy

Molecular spectroscopy is an area of research where instrumental innovation, such as the development of new sources of light or specific experimental set-up, plays a key role. In this framework we develop at LISA, in collaboration with the AILES Beamline in the Synchrotron Radiation Center SOLEIL, a cooling cell for the study by high-resolution infrared spectroscopy of complex systems that decomposes rapidly at room temperature. Indeed, low-temperature measurement allows in some cases to study molecules under in situ conditions of observation and in many cases to depopulate the excited vibrational or rotational levels, indispensable for analysis and modeling. This cell will also allow to study the variation of the pressure-broadening coefficients as a function of the temperature, essential for the analysis of atmospheric spectra.

The objective is to generate optical paths of the order of 100 meters in a cooled chamber in a homogeneous and controlled manner between 300 and 100 K, vacuum-insulated systems to generate gaseous mixtures or vacuum insulation without generating vibration parasite, harmful to the quality of the measurement. Long distance cooling gas cells have been already carried out in the past in different groups, but we want to develop a specific assembly, optimized for mid-infrared from 10 µm and far-infrared up to 300 µm and allowing easy switching between these domains on the same samples and compatible with oxidants or halogenated gases. An example is chlorine nitrate ClONO2, of atmospheric interest, that we want to study. The experiments will focus on the band at 123 cm-1, involved in the analysis of the hot bands situated in the (mid-infrared) regions where ClONO2 is detected.