Aparato experimental para espectroscopia da transição 1S–2S do hidrogênio via sublimação de matriz de isolamento

Abstract

This work presents the design and installation of an experimental apparatus for 1S-2S spectroscopy of the hydrogen atom using the Matrix Isolation Sublimation (MISu) technique. In this technique, an atomic beam is produced by growing a neon matrix on a cold substrate, implanting lithium and hydrogen atoms into the matrix via laser ablation of a LiH solid, and subsequently sublimating the matrix by applying a heat pulse to the substrate. The spectroscopic process consists of exciting the hydrogen atoms from the 1S state to the 2S state in an optical cavity, then bringing them into a mixture with the 2P state by means of an electric field. The decay to the 1S state produces Lyman-α photons, which eject electrons from the surface of the detection cell. These electrons are captured by a Channel Electron Multiplier (CEM), generating a detectable electrical signal. The atomic beams produced were characterized by lithium optical spectroscopy, presenting temperatures close to 1 K and velocities of about 125 m/s, results that are competitive internationally. A toy model was developed to simulate the emission of Lyman-α photons and the detection of electrons, considering the spatial distribution of the excited atoms. The simulations indicate efficiency between 15% and 30%. The results obtained with the experimental apparatus showed that electrons released during sublimation generate noise above the expected signal, pointing to the need for improvements in the apparatus for future observation of the 1S-2S spectrum of hydrogen.