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Abstract: The multicharged carbon ions are produced in the laser ionization of molecular benzene beam seeded in noble gas by a nanosecond Nd-YAG laser with intensities of ∼1011Wcm−2 at 1064 and 532nm. The He-like C4+ ions are the dominant carbon ions at 1064nm, while C2+ ions are the main multicharged ions at 532nm. When the laser wavelength is changed to 355 and 266nm, only singly charged ions are observed. The multicharged atomic ions are probably produced in Coulomb explosion of highly charged benzene ions. [Copyright &y& Elsevier]

The direct hydrogen abstraction reaction of H atom with (CH3CH2)2SiH2 has been studied using ab initio molecular orbital theory. Theoretical analysis provided conclusive evidence that the main process occurring is the hydrogen abstraction from the Si–H bond. The kinetic calculations of the reaction have been explored using the canonical variational transition-state theory (CVT) methods with no tunneling correction, zero-curvature tunneling (ZCT) correction, and small-curvature tunneling (SCT) correction over the temperature range of 200–2000 K. At the 305 K, the calculated CVT/SCT rate constant is in excellent agreement with the only available experimental value. [Copyright &y& Elsevier]

Geometry optimization and harmonic vibrational frequency calculations have been performed on the X˜2A1 state of NO2 and X˜1A1 state of NO2−. Franck–Condon analyses and spectral simulations were carried out on the NO2(X˜2A1)–NO2−(X˜1A1) photo-detachment process. In addition, the equilibrium geometry parameters, r(NO)=1.248 ± 0.005 A˚ and ∠(ONO)=116.8 ± 0.5°, of the X˜1A1 state of NO2−, are derived by employing an iterative Franck–Condon analysis procedure in the spectral simulation. Our conclusions regarding the anion geometry suggest a reinterpretation of the results of Woo et al. [Phys. Rev. A 24 (1981) 1380]. [Copyright &y& Elsevier]

This paper investigated the dependence of multiply charged ions on the laser polarization state when benzene cluster was irradiated with 532 and 1064 nm nanosecond laser. A circle, square and flower distribution for C 2+ , C 3+ and C 4+ were observed with 532 nm laser respectively, while flower petals for C 2+ , C 3+ and C 4+ were observed at 1064 nm as the laser polarization varied. A theoretical calculation was performed to interpret the polarization state and wavelength dependence of the multiply charged ions. The simulated results agreed well with the experimental observation with considering the contribution from the cluster disintegration. [ABSTRACT FROM AUTHOR]

Abstract: To understand the production mechanisms for multiply charged ions C q + (q =2–3) and I q + (q =2–4), the kinetic energy of released electron was measured for understanding the interaction of nanosecond laser with CH3I cluster. The mean electron energy increased from 19 to 33eV as the laser intensity was raised from 2.9×109 to 4.7×1010 W/cm2. The evolution of the mean electron energy as a function of laser intensity was similar to that of multiply charged ions, which indicated that electron impact ionization played an important role in the formation of C q + (q =2–3) and I q + (q =2–4). Moreover, the formation of more ionized sites would lead to the cluster splitting, which is disadvantageous for the multiply charged ion production. [Copyright &y& Elsevier]

Abstract: The adsorption of FePc on the Ag(110) substrate has been investigated by ultraviolet photoelectron spectroscopy (UPS). The emission features corresponding to the adsorbed organic molecules are located at 1.03, 4.04, 6.53 and 9.22eV below the Fermi level. The features shift in binding energy with increasing the thickness of the organic films indicates an interaction between FePc and the Ag(110) substrate. ARUPS measurements suggest that the molecular plane is nearly parallel to the substrate in the case of a monolayer. The theoretical calculation confirms the experimental results and indicates that the top site is the most stable adsorption configuration. [Copyright &y& Elsevier]

Abstract: The ordered adsorption structures of FePc on Cu (100) have been studied by scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. With the deposition rate beyond 0.5 ML per min, the FePc molecules are not deposited dispersedly but are deposited as molecular clusters. After the heat treatment (the temperature higher than 420K), the ordered organic structures of p(5×2) or p(2×5) are obtained. The ordered adsorption structures are in the tilt adsorption model. The FePc molecules in the different domains are aligned along the [011] or [] azimuth, respectively, the molecules are tilted. [Copyright &y& Elsevier]

Abstract: The monolayer structures of perylene adsorbed on Ag(110) surface were studied by combining scanning tunneling microscopy (STM) experiments and density functional theory (DFT) calculations. Several superstructures (i.e. loose and compact dimer structures, compact trimer structures) were observed. DFT calculation results show that the interaction between molecule and Ag substrate is weak, the intermolecular interaction is comparable with that between molecule and substrate. The organic self-assembly on metal surface results from the balance between intermolecular interaction and molecule–substrate interaction. On Ag(110) surface, the dimer-α structure was found to be more stable than other structures. [Copyright &y& Elsevier]

Abstract: The electron energies were measured to investigate the influences of laser intensity and wavelength on the ion charge state distribution of C q + (q =2–4) when benzene clusters were irradiated by 109–1011 W/cm2 nanosecond laser pulses. The results show that the ratios of C q +/C( q −1)+ strongly depend on laser wavelength but slightly on laser intensity. The mean electron energy up to 100eV was measured, which was qualitatively consisted with the ‘multiphoton ionization ignition-inverse bremsstrahlung heating-electron impact ionization’ three-stage model. The screening effects inside clusters can significantly decrease the ionization potentials of C q + and facilitate the formation of multiply charged ions especially at low laser intensity. [Copyright &y& Elsevier]

Abstract: Resonance Raman spectra were obtained for p-nitrobenzoic acid using 266, 252.7, and 228.7nm excitations. The spectra display overtones of the nominal NO2 symmetric stretch mode ν 12 and the nominal NO2 antisymmetric stretch ν 8, and their combination bands with other four vibrational modes ν 19, ν 22, ν 17 and ν 10. A preliminary resonance Raman intensity analysis was done and the results for p-nitrobenzoic acid were compared with nitrobenzene, p-nitroaniline and p-nitrophenone. The results presented here indicate that the Franck–Condon region structure dynamics of nitroaromatic molecules will be dominated by nitro group when both –NO2 and –COOH or –COCH3 chromophores are coexisted in these kinds of molecules. [Copyright &y& Elsevier]

Abstract: Deposition of fluorene-1-carboxylic acid molecules on Cu(110) surface has been investigated by LEED and STM. By saturating the surface with one monolayer, a (4×4) pg ordered structure is formed judged from the LEED pattern. STM image shows that the ordered structure is formed in small locally areas. STM results indicate that the molecular aromatic plane of FC-1 is parallel to the substrate. First-principle calculations determined the favorable adsorption site. The adsorption structure presents a chiral property. Two FC-1 molecules, in one unit cell, have their carboxylic groups bonded in identical geometry and equivalent orientation, but with opposite chirality. [Copyright &y& Elsevier]

Abstract: Resonance Raman spectra were acquired for acetophenone using 228.7, 239.5, and 245.9nm excitations in cyclohexane solution. The spectra display overtones of the benzene ring C–C stretch (1578cm−1) and the carbonyl C (1671cm−1) modes and their combination bands with other five vibrational modes. A preliminary resonance Raman intensity analysis was done and these results for acetophenone were compared to the those previously reported for 2-hydroxyacetophenone. The differences between the vibrational reorganizational energies for acetophenone relative to those of 2-hydroxyacetophenone were briefly discussed. [Copyright &y& Elsevier]

Abstract: Resonance Raman spectra of p-nitroacetophenone(PNAP) have been obtained in resonance with the charge-transfer (CT) band using 252.7, 266 and 273.9nm in methanol solvent. The spectra indicate that the Franck–Condon region photodissociation dynamics have multidimensional character with motion mainly along the Cing ν 8(1691cm−1) and the benzene ring stretch ν 10(1593cm−1). A preliminary resonance Raman intensity analysis was done and the results for PNAP were compared with nitrobenzene and aceptophenone. Our results indicate that –NO2 is more photoactive than –COCH3. The isomerization process of PNAP takes place somewhere after the wave packet leaves the Franck–Condon region. [Copyright &y& Elsevier]

Cluster assisted photoionization processes of benzene, which was seeded in argon, induced by an intense 25 ns Nd-YAG laser has been studied by means of time-of-flight mass spectrometry. At the laser intensity of 1011 W/cm2, multicharged ions Cq+ (q=2–3) with kinetic energy up to 150 eV were observed in the mass spectra. Strong evidences support that these ions are formed in the Coulomb explosion of multicharged benzene cluster ions. [Copyright &y& Elsevier]