Spectroscopy of molecules in very high rotational states using an optical centrifuge

Abstract

We have developed a high power optical centrifuge for measuring the spectroscopy of molecules in extreme rotational states. The optical centrifuge has a pulse energy that is more than 2 orders of magnitude greater than in earlier instruments. The large pulse energy allows us to drive substantial number densities of molecules to extreme rotational states in order to measure new spectroscopic transitions that are not accessible with traditional methods. Here we demonstrate the use of the optical centrifuge for measuring IR transitions of N₂O from states that have been inaccessible until now. In these studies, the optical centrifuge drives N₂O molecules into states with J ∼ 200 and we use high resolution transient IR probing to measure the appearance of population in states with J = 93–99 that result from collisional cooling of the centrifuged molecules. High resolution Doppler broadened line profile measurements yield information about the rotational and translational energy distributions in the optical centrifuge.