Vacuum ultraviolet negative photoion spectroscopy of chloroform.

Negative ions Cl(-), Cl(2)(-), CCl(-), CHCl(-), and CCl(2)(-) are observed in vacuum-ultraviolet ion-pair photodissociations of chloroform (CCl(3)H) using the Hefei synchrotron radiation facility, and their ion production efficiency curves are recorded in the photon energy range of 10.00-21.50 eV. Two similar spectra of the isotope anions (35)Cl(-) and (37)Cl(-) indicate the following: Besides the strong bands corresponding to the electron transitions from valence to Rydberg orbitals converging to the ionic states, some additional peaks can be assigned with the energetically accessible multibody fragmentations; a distinct peak at photon energy 14.55 eV may be due to a cascade process (namely, the Cl(2) neutral fragment at the highly excited state D'2(3)Π(g) may be produced in the photodissociation of CCl(3)H, and then the Cl(-) anions are produced in the pulsed-field induced ion-pair dissociations of Cl(2) (D'2(3)Π(g))); two vibrational excitation progressions, nν(2)(+) and nν(2)(+) + ν(3)(+), and nν(4)(+) and nν(4)(+) + ν(2)(+), are observed around C̃ (2)E and D̃ (2)E ionic states, respectively. The enthalpies of the multibody fragmentations to Cl(2)(-), CCl(-), CHCl(-), and CCl(2)(-) are calculated with the thermochemistry data available in the literature, and these multibody ion-pair dissociation pathways are tentatively assigned in the respective anion production spectra.

Does the incoming oxygen atom influence the geometries and the electronic and magnetic structures of Co(n) clusters?

The small-sized Co(n)O (n = 1-5) clusters with different spin states have been systematically investigated by using the density-functional approach. The total energies, equilibrium geometries, and magnetic properties are discussed. Equilibrium geometries and the relative stabilities in terms of the calculated fragmentation energies are discussed, manifesting that the remarkable stable small-sized cluster corresponds to the Co(2)O isomer, and that the O atom prefers the surface-capped pattern on Co(n) (n > 2) clusters and bonds with three Co atoms simultaneously. Furthermore, the calculated averaged atomic magnetic moments of Co(n)O (n = 1-5) clusters exhibit that the septet Co(2)O structure has the biggest averaged atomic magnetic moment of 2.0 mu(B)/atom, it is interesting that the oxygen capped Co(n) (n = 1-5) clusters retain the magnetic properties of bare transition metal (TM) Co(n) clusters. In addition, the distribution of electron density of the HOMO states for the most stable Co(n)O clusters mainly localizes around Co(n) atoms while the distribution around O atom is very low, and their shapes of the HOMO and bonding properties between bare Co(n) clusters and Co(n)O clusters are obviously different. The calculated electron affinities and experimental results (J. Phys. Chem. A 2002, 106, 4891) show that the incoming oxygen atom causes a minor influence on the electronic properties of Co(n) clusters. Comparisons of the calculated ionization potentials (IPs) for CoO and Co(2)O clusters with available experimental measurements are made.

Geometries and stabilities of the carbon clusters with the rhodium impurity: a computational investigation.

A density functional study of the RhCn(n = 1-6) clusters with different spin states has been carried out systematically by using the B3LYP/Lan2DZ method. The equilibrium geometries associated with total energies and natural populations of RhCn (n = 1-6) clusters are calculated and presented. Stabilities and electronic properties are discussed in detail. The relative stabilities in term of the calculated fragmentation energies show that the lowest-energy RhCn clusters with rhodium atom being located at terminal of carbon chain are the linear geometries and the ground states of the RhCn clusters alternate between doublet (for n-odd members) and quartet (for n-even members) states. Furthermore, the calculated fragmentation energies of the RhCn show strong even-odd alternations: the RhCn clusters with an odd number of carbon atoms are more stable than those with an even number ones. In addition, we comment on the charge transfer and chemical bonding properties within the clusters.

Characterization of products from photooxidation of toluene.

Photooxidation reaction of toluene in smog chamber systems was initiated by the UV radiation of toluene/CH3ONO/NOx mixtures. The products of the photooxidation reaction of toluene and its subsequent reactions were analyzed directly utilizing Fourier transform infrared spectrometer (FTIR). Detailed assignments to FTIR spectrum of gas-phase products were given. The information of some important functional groups in the products, such as, carbonyl groups (C-O), hydroxyl groups ( -OH), carboxylic acid (-COOH), C-C bonding, N-O bonding and C-H bonding (C-H), was got from this analysis. These results were compared to those analyzed by aerosol time of flight mass spectrometer (ATOFMS). It was found that there are some differences between FTIR analysis of gas-phase products and that of particle-phase, for example, the products with carbonyl groups, which were connected to unsaturated chemical bonds, was relatively higher in the gas phase, while ketones, aldehydes, carboxylic acid and organonitrates were the dominant functional groups in the aerosol-phase reaction products. The possible reaction pathways of some important products in the gas phase were also discussed.