Excitation dynamics involving homogeneous multistate interactions: one and two color VMI and REMPI of HBr.

Velocity map imaging (VMI) data and mass resolved REMPI spectra are complementarily utilized to elucidate the involvement of homogeneous multistate interactions in excited state dynamics of HBr. The HΣ(v' = 0) and EΣ(v' = 1) Rydberg states and the VΣ(v'= m + 7) and VΣ(v'= m + 8) ion-pair states are explored as a function of rotational quantum number in the two-photon excitation region of 79 100-80 700 cm. H and Br images were recorded by one- as well as two-color excitation schemes.

Effect of a triplet to singlet state interaction on photofragmentation dynamics: highly excited states of HBr probed by VMI and REMPI as a case study.

Analysis of mass resolved spectra as well as velocity map images derived from resonance enhanced multiphoton ionization (REMPI) of HBr via resonance excitations to mixed Rydberg (6pπ Σ(v' = 0)) and valence (ion-pair) (V Σ(v' = m + 17)) states allows characterization of the effect of a triplet-to-singlet state interaction on further photoexcitation and photoionization processes. The analysis makes use of rotational spectra line shifts, line intensity alterations, kinetic energy release spectra as well as angular distributions. Energy-level-dependent state mixing of the resonance excited states is quantified and photoexcitation processes, leading to H formation, are characterized in terms of the states and fragmentation processes involved, depending on the state mixing.

Rydberg and valence state excitation dynamics: a velocity map imaging study involving the E-V state interaction in HBr.

Photoexcitation dynamics of the E((1)Σ(+)) (v' = 0) Rydberg state and the V((1)Σ(+)) (v') ion-pair vibrational states of HBr are investigated by velocity map imaging (VMI). H(+) photoions, produced through a number of vibrational and rotational levels of the two states were imaged and kinetic energy release (KER) and angular distributions were extracted from the data. In agreement with previous work, we found the photodissociation channels forming H*(n = 2) + Br((2)P3/2)/Br*((2)P1/2) to be dominant.

A Multipronged Comparative Study of the Ultraviolet Photochemistry of 2-, 3-, and 4-Chlorophenol in the Gas Phase.

The S1((1)ππ*) state of the (dominant) syn-conformer of 2-chlorophenol (2-ClPhOH) in the gas phase has a subpicosecond lifetime, whereas the corresponding S1 states of 3- and 4-ClPhOH have lifetimes that are, respectively, ∼2 and ∼3-orders of magnitude longer. A range of experimental techniques-electronic spectroscopy, ultrafast time-resolved photoion and photoelectron spectroscopies, H Rydberg atom photofragment translational spectroscopy, velocity map imaging, and time-resolved Fourier transform infrared emission spectroscopy-as well as electronic structure calculations (of key regions of the multidimensional ground (S0) state potential energy surface (PES) and selected cuts through the first few excited singlet PESs) have been used in the quest to explain these striking differences in excited state lifetime. The intramolecular O-H···Cl hydrogen bond specific to syn-2-ClPhOH is key.

Uptake of atmospheric molecules by ice nanoparticles: pickup cross sections.

Uptake of several atmospheric molecules on free ice nanoparticles was investigated. Typical examples were chosen: water, methane, NO(x) species (NO, NO(2)), hydrogen halides (HCl, HBr), and volatile organic compounds (CH(3)OH, CH(3)CH(2)OH). The cross sections for pickup of these molecules on ice nanoparticles (H(2)O)(N) with the mean size of N≈260 (diameter ~2.