Photoionization and photodissociation of HCl(B [sup 1]Σ[sup +],J=0) near 236 and 239 nm using three-dimensional ion imaging (original) (raw)

Intermediate state polarization in multiphoton ionization of HCl

The Journal of Chemical Physics, 2006

The paper presents the detailed theoretical description of the intermediate state polarization and photofragment angular distribution in resonance enhanced multiphoton ionization ͑REMPI͒ of molecules and the experimental investigation of these effects in the E 1 ⌺ + and V 1 ⌺ + 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 , vЈ =0← X , vЉ =0͒ and ͑V , vЈ =12← X , vЉ =0͒ transitions and REMPI via the Q͑0͒ and Q͑1͒ 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 Q͑1͒ rotational transition show good agreement with theoretical prediction.

Ultraviolet photodissociation of HCl in selected rovibrational states: Experiment and theory

The Journal of Chemical Physics, 2000

Experimental and theoretical methods have been applied to investigate the effect of internal parent excitation on the ultraviolet photodissociation dynamics of HCl (X 1 ⌺ ϩ ) molecules. Jet-cooled H 35 Cl molecules within a time-of-flight mass spectrometer were prepared by infra-red absorption in the following quantum states: vϭ1, Jϭ0 and Jϭ5; vϭ2, Jϭ0 and Jϭ11; vϭ3, Jϭ0 and Jϭ7. The excited molecules were then photodissociated at ϳ235 nm and the Cl( 2 P j ) photofragments detected using ͑2ϩ1͒ resonance enhanced multiphoton ionization. The results are presented as the fraction of total chlorine yield formed in the spin-orbit excited state, Cl( 2 P 1/2 ). The experimental measurements are compared with the theoretical predictions from a time-dependent, quantum dynamical treatment of the photodissociation dynamics of HCl (vϭ1Ϫ3, Jϭ0͒. These calculations involved wavepacket propagation using the ab initio potential energy curves and coupling elements previously reported by Alexander, Pouilly, and Duhoo ͓J. Chem. Phys. 99, 1752 ͑1993͔͒. The experimental results and theoretical predictions share a common qualitative trend, although quantitative agreement occurs only for HCl (vϭ2).

Ultraviolet photodissociation of HCl in selected rovibrational states: Experiment …

The Journal of …

Experimental and theoretical methods have been applied to investigate the effect of internal parent excitation on the ultraviolet photodissociation dynamics of HCl (X 1 ⌺ ϩ ) molecules. Jet-cooled H 35 Cl molecules within a time-of-flight mass spectrometer were prepared by infra-red absorption in the following quantum states: vϭ1, Jϭ0 and Jϭ5; vϭ2, Jϭ0 and Jϭ11; vϭ3, Jϭ0 and Jϭ7. The excited molecules were then photodissociated at ϳ235 nm and the Cl( 2 P j ) photofragments detected using ͑2ϩ1͒ resonance enhanced multiphoton ionization. The results are presented as the fraction of total chlorine yield formed in the spin-orbit excited state, Cl( 2 P 1/2 ). The experimental measurements are compared with the theoretical predictions from a time-dependent, quantum dynamical treatment of the photodissociation dynamics of HCl (vϭ1Ϫ3, Jϭ0͒. These calculations involved wavepacket propagation using the ab initio potential energy curves and coupling elements previously reported by Alexander, Pouilly, and Duhoo ͓J. Chem. Phys. 99, 1752 ͑1993͔͒. The experimental results and theoretical predictions share a common qualitative trend, although quantitative agreement occurs only for HCl (vϭ2).

HCl+Xvibrational states investigated from the HCl threshold photoelectron spectrum

Physical Review A, 1991

The threshold photoelectron spectrum of HC1 has been investigated in the 980-760-A region. The various autoionization processes leading to the observed resonances are discussed. From the resonance positions 1ocated at the successive vibrational thresholds, spectroscopic constants of the X H state of HC1+ have been determined.

Assignment of the photoelectron spectrum of HCl above 20 eV

Chemical Physics Letters, 1993

The photoelectron spectrum of HCI up to 32 eV is analyzed with ab initio MO CI calculations. The potential energy curves of most of the highly excited states of the ion HCl* are correctly drawn to near the dissociation limit, and the Franck-Condon factors (FCF) from the neutral ground state are evaluated. By comparing the experimental spectrum with the theoretical FCF distribution, six observed bands between 20 and 32 eV are assigned. One ofthem turns out to be a Rydberg state converged to the ground state of HCl'+

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

Journal of Atomic, Molecular, and Optical Physics, 2011

The competition between multiphoton ionization and fragmentation in the diatomic molecule hydrogen chloride is reviewed. Emphasis is laid on recent experimental results employing chemical imaging methods in order to obtain kinetic energy distributions and angular distributions of photoproducts. The energy range considered is 15 to 20 eV, equivalent to the absorption of three or four photons in the ultraviolet wavelength range. The role of Rydberg states as resonantly excited intermediate states in the ionization/fragmentation processes is assessed. Mixing among 1 Σ + states gives rise to peculiarly shaped double minimum potential energy curves which allow for the production of hydrogen and chlorine atomic and ionic fragments via several competing pathways, in addition to the production of molecular HCl + ions. States with different electronic properties show a qualitatively different behaviour from Σ + states. Accidental resonances between states of differing orbital angular momentum or multiplicity serve to override these differences and cause subtle as well as significant deviations from the unperturbed behaviour.

Photodissociation processes in the HCl molecule

Journal of Chemical Physics, 1982

Various ab initio methods have been employed for the study of photodissociation processes in the HCI molecule. Potential curves for selected singlet and triplet states and dipole transition moments between singlet states have been calculated. The transition moments vary significantly with internuclear distance for all states studied. The lifetime of the B 1,2' + state is predicted to be 3 ns. The calculations show that photodissociation of Hel occurs by absorption into the repulsive A III state and by absorption into the bound C III state, followed by predissociation. The theoretical photodissociation cross sections for the A III state and oscillator strengths for the C I II state are in good agreement with experimental data. The contributions from other excited states are investigated. The photodissociation rate of HCl in diffuse interstellar clouds is computed.

Simultaneous imaging of both product ions: exploring gateway states for HCl as a benchmark molecule

Physical Chemistry Chemical Physics, 2014

Simultaneous imaging of both positive and negative product ions is used to exclusively study photoion pair formation free from interference of competing fragmentation channels. Resonance enhanced multiphoton excitation allows us to interrogate potential energy surfaces for vastly differing molecular geometries. 3D imaging provides complete fragment information. We applied the technique to HCl as a benchmark and identified the gateway state leading to photoion pairs. The approach can easily be applied to any molecule exhibiting a potential with an attractive part at large internuclear distances.

Photoabsorption, photodissociation, and photoionization cross sections of HCl

Physical Review A, 1990

Absolute absorption, ionization, and dissociation cross sections of HCl have been measured in the 980-720-A spectral range. Dipole moments have been obtained for several transitions. A quantum-defect-theory model with quantum-defect functions is used to describe the observed structures. The possible predissociation mechanisms are discussed. The dissociation excitation spectrum of DCl is assigned in the same way.