6533b820fe1ef96bd127a665

RESEARCH PRODUCT

Echo-assisted impulsive alignment of room-temperature acetone molecules

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International audience; We experimentally and theoretically investigate the field-free alignment of the asymmetric-top acetone molecule. Our study shows that the production of postpulse aligned molecules in a dense sample (0.05-0.2 bar) of room-temperature acetone using a single-pulse excitation can be significantly improved by rotational alignment echoes induced in a two-pulse excitation scheme. We report the observation of fractional echoes that can be used to reveal the nonlinearity of the molecular system. In a proof-of-principle experiment, a pre-aligned sample of acetone is also used for third-harmonic generation. The analysis of the experimental data with numerical simulations based on quantum and classical models enables the determination of the collisional decay rate of acetone alignment, as well as a test of the static, second-order, electric hyperpolarizabilities of the molecule derived from ab initio calculations presented in this work.