Cavity ring-down spectroscopy of cold molecular samples

Cavity ring-down spectroscopy is a sensitive spectroscopic technique that allows to measure spectra of atoms, molecules or gas mixtures. This work presents the design and the results obtained with the first homemade CRDS experimental set-up in Universit´e catholique de Louvain. Simulations of a part of the visible absorption spectrum of H2O16 are presented and compared to experimental measurements. This comparison allows to assign rovibrational transitions starting from the ground vibrational state (v1 = 0, v2 = 0, v3 = 0) and reaching rotational states belonging to the (v1 = 3, v2 = 1, v3 = 1) vibrational states. This work presents the design and results obtained with a pulsed cavity ring-down spectrometer, the first built in UCL, working in the visible range (610 to 670 nm). This set-up has been characterised and presents a sensitivity of amin = 5.10^(-8) cm^(-1) and a resolution of 0.4 cm^(-1). Some preliminary simulations that pave the way to low temperature measurements are also detailed in this work.