Laser induced alignment and orientation of conformer and quantum state selected gas-phase molecules and their applications

Summary form only given. Molecules in the gas-phase can be treated as isolated systems without influence from the environment. Gaining further control over the molecules, such as quantum state or conformer selection, or/and fixing the molecular axis in space, can be highly advantageous or simply necessary for a variety of experiments aiming at, for instance, probing of the molecular structure, or molecular frame dependent properties such as molecular-frame photo angular distributions.Here, we present the generation of a cold (~ 1 K), conformer and quantum-state selected molecular beam [1], which is used in combination with a strong laser field to manipulate the orientation of molecules in space. We demonstrate several ways of aligning the molecular ensemble by the use of 800 nm radiation. We show a general approach to strongly align complex molecules in space by the use of a chirped laser pulse (≈ 100 ps pulse duration) provided by a Ti:Sapphire laser system [2-4]. We also demonstrate how a short train of fs laser pulses can be used to strongly align molecules in a field-free regime. Additionally we show how the laser pulses can be used in combination with strong DC electric fields to orient the molecules in the laboratory frame. We discuss how the experiments that aim at the structure determination of the molecules such as (hard) x-ray diffraction, electron diffraction, or laser-induced electron diffraction can be improved by maximizing the degree of alignment/orientation, and we show molecular-frame photo angular distribution measurements of an aligned ensemble of indole molecules.