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Abstract

This Master Thesis is dedicated to implementing, characterizing, and testing a liquid crystal-based flat jet system for high-order harmonic generation (HHG) studies. A comprehensive chapter is devoted to describing the technical implementation of the system, with special focus on the temperature control of the flowing liquid crystal (LC). In the isotropic phase, the LC flat jet presented a thermal stability of 1.40 ±0.07 ^◦C. The subsequent chapter deals with the characterization of the delivered LC sheets, whose dimensions were measured for different impingement conditions. In particular, the thicknesses were determined by an IR-autocorrelator, achieving thicknesses down to 2 ±1 μm. The refreshment rates of the sample were calculated, ensuring that each laser pulse ‘sees’ a new volume of LC. Through cross-polarized microscopy, it was established that a certain degree of alignment is naturally being imposed on the flowing molecules. In the last chapter, the device was tested upon HHG experiments on 5CB. Harmonics up to the 15^th and 13^th were observed in the isotropic and nematic phases, respectively; and the non-perturbative nature of the emitted harmonics was proven. The harmonics yield was measured as a function of the driving field polarization. The resulting angular distributions are qualitatively in agreement with previous results.