Intermediate state polarization in multiphoton ionization of HCl

Abstract

The paper presents the detailed theoretical description of the intermediate state polarization and photofragment angular distribution in resonance enhanced multiphoton ionization (REMPI) of molecules and the experimental investigation of these effects in the E(1)Sigma(+) and V(1)Sigma(+) states of HCl populated by two-photon transitions. It is shown that the intermediate state polarization can be characterized by the universal parameter b which is in general a complex number containing information about the symmetry of the two-photon excitation and possible phase shifts. The photofragment angular distribution produced by one- or multiphoton excitation of the polarized intermediate state is presented as a product of the intermediate state axis spatial distribution and the angular distribution of the photofragments from an unpolarized intermediate state. Experiments have been carried out by two complementary methods: REMPI absorption spectroscopy of rotationally resolved (E,v'=0<--X,v"=0) and (V,v'=12<--X,v"=0) transitions and REMPI via the Q(0) and Q(1) rotational transitions followed by three-dimensional ion imaging detection. The values of the parameter b determined from experiment manifest the mostly perpendicular nature of the initial two-photon transition. The experimentally obtained H(+) -ion fragment angular distributions produced via the Q(1) rotational transition show good agreement with theoretical prediction.

Polarization of molecular angular momentum in the chemical reactions Li + HF and F + HD

“…A compact and convenient spherical tensor expression for the intensity of the REMPI 2 + 1 signal which is valid for the pure linearly, or circularly polarized probe light can be written in the form 102,103 …”

The polarisation of two-photon excited fluorescence in rotating molecules

“…), see [7,8,[11][12][13][14][15][16] and references therein, however a number of studies have been carried out in the gas phase [17][18][19][20][21][22][23][24][25]. The gas phase/molecular beam studies are of fundamental importance for understanding the TPEF dynamics of polyatomic molecules in the collision-free regime because they can be supported by high accuracy quantum mechanical ab initio calculations which in most cases are not available for the condensed matter studies.…”

Multiphoton Ionization and Fragmentation of Hydrogen Chloride: A Diatomic Still Good for a Surprise

“…The angular momentum polarization produced by twophoton absorption can be described by formalisms outlined by Manzhos et al [1] and by Chichinin et al [21]. In the axial recoil approximation the angular photoproduct distribution can be presented as a product of the excited state axis spatial distribution and the angular distribution of the photofragments produced via photolysis from an unpolarized excited state.…”

“…Following the formalism outlined by Chichinin et al [21] one obtains for the observed angular distribution of the photoproduct P(θ):…”

“…Photoproduct spatial anisotropies and kinetic energy distributions were analyzed by Loock and coworkers [1,3,19] and by Gericke and co-workers [20,21] using velocity map imaging techniques. Both groups investigated the ionization/fragmentation pathways through various vibrational bands of the B 1 Σ + (0 + ) state.…”