ALIGNMENT OF NEUTRAL MOLECULES BY A STRONG NONRESONANT LASER FIELD

We show that a strong nonresonant nanosecond laser pulse can be used to align neutral molecules. Our technique, applicable to nonpolar as well as polar molecules, relies on the anisotropic interaction between the strong laser field and the induced dipole moment of the molecules. The degree of alignment is enhanced by increasing the laser intensity or by lowering the initial rotational temperature of the molecules. We measure the alignment by photodissociating the molecules with a femtosecond laser pulse and detecting the instantaneous direction of the photofragments by ion imaging techniques. The highest degree of alignment is ≪cos²θ≫ = 0.81.