On the Stark effect in open shell complexes exhibiting partially quenched electronic angular momentum: Infrared laser Stark spectroscopy of OH–C2H2, OH–C2H4, and OH–H2O

Abstract

a b s t r a c tThe Stark effect is considered for polyatomic open shell complexes that exhibit partially quenched electronic angular momentum. Matrix elements of the Stark Hamiltonian represented in a parity conserving Hund's case (a) basis are derived for the most general case, in which the permanent dipole moment has projections on all three inertial axes of the system. Transition intensities are derived, again for the most general case, in which the laser polarization has projections onto axes parallel and perpendicular to the Stark electric field, and the transition dipole moment vector is projected onto all three inertial axes in the molecular frame. Simulations derived from this model are compared to experimental rovibrational Stark spectra of OH-C 2 H 2 , OH-C 2 H 4 , and OH-H 2 O complexes formed in helium nanodroplets.

Mid-infrared signatures of hydroxyl containing water clusters: Infrared laser Stark spectroscopy of OH–H2O and OH(D2O)n (n = 1-3)

“…We recently reported an effective Hamiltonian approach for modeling the Stark effect in polyatomic open shell complexes that exhibit partially quenched electronic angular momentum. 74 With this model, we can extract permanent electric dipole moments from Stark spectra of the OH-H(D) 2 O complexes. Figures 6 and 7 show Stark spectra for OH-D 2 O and OH-H 2 O, respectively.…”

Infrared Spectroscopy of Molecular Radicals and Carbenes in Helium Droplets

“…Simulations of rotationally resolved spectra of helium-solvated molecules can be achieved by employing traditional effective Hamiltonian approaches, in which a gas-phase Hamiltonian is used with renormalized rotational constants. Moreover, Stark spectroscopy can be implemented and analyzed in the traditional sense, in which an external electric field perturbs the free-rotor behavior of the molecule or complex, and an additional term is appended to the zero-field effective Hamiltonian to account for the field-induced perturbation [41]. Our instrument is equipped with a laser multipass cell (Fig.…”

“…4.1c) that allows us to perform Stark spectroscopy measurements by applying a static electric field (0 to 80 kV/cm) to electrodes that surround the droplet beam/laser interaction region. The use of various Stark field strengths and laser polarization orientations (leading to different selection rules), allows us to accurately determine dipole moments of He-solvated species [21,41,44,65,66]. For example, the experimental (black) and simulated (red) Stark spectra of the linear OH-CO complex are shown in Fig.…”