Alignment of the hydrogen molecule under intense laser fields

摘要

Alignment of the electronically excited E,F state of the H-2 molecule is studied using the velocity mapping imaging technique. Photofragment images of H+ due to the dissociation mechanism that follows the 2-photon excitation into the (E,F; nu = 0, J = 0) electronic state show a strong dependence on laser intensity, which is attributed to the high polarizability anisotropy of the H-2 (E,F) state. We observe a marked structure in the angular distribution, which we explain as the interference between the prepared J = 0 and Stark-mixed J = 2 rovibrational states of H-2, as the laser intensity increases. Quantification of these effects allows us to extract the polarizability anisotropy of the H-2 (E,F J = 0) state yielding a value of 312 +/- 82 a.u. (46 angstrom(3)). By comparison, CS2 has 10 angstrom(3), I-2 has 7 angstrom(3), and hydrochlorothiazide (C7H8ClN3O4S2) has about 25 angstrom(3) meaning that we have created the most easily aligned molecule ever measured, by creating a mixed superposition state that is highly anisotropic in its polarizability. Published by AIP Publishing.