Chemical Physics Letters (v.382, #3-4)

The p-electron dominant contributions to the outer valence shell of 2,6-stelladione (C8H8O2) are analyzed using binding energy spectra and the orbital momentum distributions obtained by experimental and theoretical electron momentum spectroscopy. The binding energy spectra are given for azimuthal angles φ=0° and 10°, respectively, in order to reveal information of the s- and p-electron dominant characteristics in these molecular orbitals. The wavefunctions in configuration space are directly mapped into momentum space using the plane wave impulse approximation. This work focuses on the interpretation of the electronic structural information and bonding mechanism of the molecule in momentum space. In particular, p-electron dominant contributions of the strained organic compound are used to support our findings.

Spectroscopic and structural study of Y2C2 carbide encapsulating endohedral metallofullerene: (Y2C2)@C82 by Takashi Inoue; Tetsuo Tomiyama; Toshiki Sugai; Hisanori Shinohara (226-231).
The first di-yttrium carbide endohedral metallofullerene has been produced and spectroscopically and structurally characterized. 13C NMR structural analyses reveal that di-yttrium endohedral metallofullerene having a molecular formula of Y2C84 has been found to possess an endohedral yttrium carbide structure, (Y2C2)@C82, in which a Y2C2 species is encaged by a C82-C3v(8) fullerene. The encaged Y2C2 species should rapidly rotate in order to maintain the entire (Y2C2)@C82 molecular symmetry unchanged at room temperature.

Adiabatic reduction and hysteresis of the LFI model for NO + NH3 on Pt{1 0 0} by H. Uecker; R. Imbihl; M. Rafti; I.M. Irurzun; J.L. Vicente; E.E. Mola (232-244).
The Lombardo–Fink–Imbihl (LFI) model for the NO + NH3 reaction on Pt{1 0 0} consists of seven coupled ordinary differential equations (ODEs). Here, we present a numerical analysis for relaxation oscillations in the LFI and show that it cannot be adiabatically reduced to two coupled ODEs. We argue that this is because of the explicit consideration of the trapping processes of NO from 1 × 1 to hex phases in the kinetic mechanism of the reaction. Our analysis shows that an adiabatic reduction to three coupled ODEs can be achieved. Moreover, we examine the hysteretic behavior in detail.

Lifetime broadening in the gas phase B ̃ 2 Π← X ̃ 2 Π electronic spectrum of C8H by Petre Birza; Dmitriy Khoroshev; Andrei Chirokolava; Tomasz Motylewski; John P. Maier (245-248).
The origin band of the B ̃ 2 Π 3 2 ← X ̃ 2 Π 3 2 electronic transition of linear C8H was recorded in a planar supersonic expansion by a cw cavity ring-down spectrometer. The C8H radical was produced using a discharge through a C2H2/He mixture inside a pulsed slit nozzle. Despite the fact that the resolution of the spectrometer is 350 MHz, which is 3–4 times higher than the separation of rotational lines in this band, the rotational structure was not resolved. It is concluded that the rotational lines are broadened by rapid radiationless transitions from the excited electronic state. Simulations of the spectrum give an estimate of 0.8 cm−1 Lorentzian linewidth which corresponds to ∼7 ps lifetime in the excited B ̃ 2 Π 3 2 electronic state.

Electronic states of SiSe: a configuration interaction study by Surya Chattopadhyaya; Kalyan Kumar Das (249-257).
The electronic spectrum of the 28Si80Se molecule within 5 eV has been studied theoretically by using relativistic configuration interaction calculations which include pseudo potentials of the atoms. Potential energy curves of electronic states which correlate with the lowest dissociation limit have been constructed. Spectroscopic parameters of 11 Λ–S states are estimated and compared with the available observed data. The effects of the spin–orbit coupling on the potential curves and spectroscopic properties are discussed. Dipole moments of some of the low-lying states are computed. Transition dipole moments of some transitions such as E 1 Σ + –X 1 Σ + and A 1 Π –X 1 Σ + are also calculated. The radiative lifetimes of A 1 Π , E 1 Σ + , and 3 1 Σ + states are reported.

Static polarizabilities of linear ether molecules are calculated using the DFT/B3LYP functional and the Sadlej basis set. A set of segment polarizabilities reproducing the total molecular polarizability is derived. Additivity and transferability of the obtained parameterization is tested on molecules in different conformations and on cyclic ethers. Relation of the calculated values to the static electric susceptibility of polyethylene and poly(ethylene oxide) is discussed.

A very simple scheme is proposed to present the SCF molecular energy exactly as a sum of one- and two-center (mono- and diatomic) energy components, accounting for the bond formation, non-bonded repulsion, promotion etc. effects on the chemical energy scale. Generalization to the correlated case is expected to be straightforward.

STM study of water adsorption on the TiO2(1 1 0)–(1 × 2) surface by P. Maksymovych; S. Mezhenny; J.T. Yates (270-276).
Adsorption of H2O on the TiO2(1 1 0)–(1 × 2) surface was studied in ultrahigh vacuum (UHV) using the scanning tunneling microscope (STM). At 300 K H2O adsorbs preferentially on the crosslinks of the TiO2(1 1 0)–(1 × 2) surface. Cooling down the surface to 110 K during H2O exposure results in adsorption on the crosslinks and other surface sites, presumably the 5-fold coordinated Ti-atoms. The reaction products, observed as bright protrusions at positive sample bias, are attributed to hydroxyl groups due to H2O dissociation. In addition, it was found that the UV-induced line-defects on the TiO2(1 1 0)–(1 × 2) surface do not interact with H2O as seen by STM.

Kinetic study of the gas-phase reaction of CF3CHFCF2CH2OH with OH radicals at 230–430 K by L Chen; K Tokuhashi; S Kutsuna; A Sekiya; Y Yonei; A Yamamoto (277-282).
The rate constants, k l, for the reaction of CF3CHFCF2CH2OH with OH radicals were measured using both absolute and relative rate methods at 230–430 K. The absolute rate constants were measured at 250–430 K using flash photolysis and laser photolysis combined with laser-induced fluorescence detection. A smog chamber/FTIR technique was used for the relative rate measurements at 230–308 K with CH2Cl2 and CHCl3 as reference compounds. The k l values obtained with the two methods were consistent within the experimental uncertainties. The temperature dependence of k l was determined to be (2.49 ± 0.30) × 10−12 exp[−(880 ± 40)/T] cm3 molecule−1 s−1. The atmospheric lifetime was estimated to be 0.34 year.

Photodissociation spectroscopy of MgCH3I+: dissociation processes via charge transfer and/or chemical bond rupture by Ari Furuya; Hironori Tsunoyama; Fuminori Misaizu; Koichi Ohno (283-290).
Photodissociation spectrum of MgCH3I+ is measured by using a reflectron time-of-flight mass spectrometer and a tunable UV laser. There are three bands peaking at about 27 200, 29 600, and 38 100 cm−1, which all originate from 2P ←  2S transition of Mg+. In the dissociation processes, five kinds of ions, CH3 +, Mg+, I+, CH3I+, and MgI+, are observed as fragments. Photodissociation spectrum is assigned by theoretical calculations, and dissociation processes are discussed from the consideration of potential energy curves including charge transfer states along the Mg–I bond distance obtained by CIS calculation.

First determination of ionization energies of phenylnitrene by Che Huijuan; Bi Huimin; Ding Rui; Wang Dong; Meng Lingpeng; Zheng Shijun; Wang Dianxun; Daniel Kam-Wak Mok; Foo-Tim Chau (291-296).
The continuous flowing beams of the triplet state phenylnitrene (PhN) species have been generated by respective pyrolysis of PhN3 at 83(±0.5) °C and phenylisocyanate (PhNCO) at 105(±0.5) °C in the quartz inlet tube loosely filled with a 30 Å molecular sieve powder supported on the quartz wool. PE spectrum of PhN is recorded in situ for the first time. The ionization energies, corresponding to different ionic states of PhN+, are determined by PES experiment and both G2 and DFT calculations. The study indicates that PhN is a diradical with C2v symmetry and has a 3A2 ground state.

A new polymorph of ZrO2 of an orthorhombic crystal structure (o-ZrO2) is derived in a mesoporous structure. It has average 15 nm crystallite size after 2 h of heating at 500 °C a mesoporous ZrO(OH)2  ·  xH2O precursor. X-ray diffractogram determines lattice parameters of a=0.3340 nm, b=0.5535 nm and c=0.6364 nm in ρ=6.96 g/cm3 density. A high-pressure phase of Pnma o-ZrO2 is known with a similar ρ=6.78 g/cm3. Mesoporous o-ZrO2 has a strong XPS bandgroup of 3d5/2 and 3d3/2 components (bandwidth ΔE b=4.6 eV) at 182.7 and 184.7 eV binding energy E b, with an additional weak bandgroup at 170–179 eV. IR spectrum infers a severely puckered structure with a corrugated surface through pores.

Mo doped vanadium oxide nanotubes: microstructure and electrochemistry by Li-Qiang Mai; Wen Chen; Qing Xu; Jun-Feng Peng; Quan-Yao Zhu (307-312).
Mo doped vanadium oxide nanotubes (VONT) were prepared via a rheological phase reaction followed by self-assembling process and were heated at 400 °C in an inert atmosphere. The nanotubes were characterized by SEM, HRTEM, XRD, Raman spectroscopy, electrochemical investigation, etc. In contrast to the undoped VONTs, the interlayer distance between oxide layers in the (V0.99Mo0.01) x ONTs increases owing to replacement of some V in nanotubes by Mo with a larger ionic radius, resulting in a shorten diffusion length of Li ions and an improved electrochemical performance. Moreover, this study reveals that the electrochemical performance of (V0.99Mo0.01) x ONTs is further enhanced by removing the residual organic template by heating in an inert atmosphere.

Optical limiting effects of multi-walled carbon nanotubes suspension and silica xerogel composite by Zhan Hongbing; Chen Wenzhe; Wang Minquan; Zhengchan; Zou Chunlin (313-317).
Nanostructured composite of multi-walled carbon nanotubes (MWNTs) doped silica xerogel matrix was prepared by sol–gel technique. The successful encapsulation of MWNTs was checked by linear transmittance spectra and scanning electrical microscope images which show that MWNTs were well dispersed in the matrix. The optical limiting responses of MWNTs suspension and xerogel composite were observed at both 532 and 1064 nm with nanosecond laser pulses and shown to be good optical limiters. The optical limiting properties of MWNTs are maintained or even improved after being introduced into solid state matrix. The implying mechanism of nonlinear absorption other than the presently accepted nonlinear scattering is proposed and discussed.

Reduction effect of pore wall and formation of Au nanowires inside monolithic mesoporous silica by Caixia Kan; Weiping Cai; Zhaosheng Li; Ganhua Fu; Lide Zhang (318-324).
This Letter reported reduction effect of pore wall on AuCl4 ions at low temperature (<100 °C) and formation of Au nanowires within pores of monolithic mesoporous silica. Such nanostructured Au/silica assembly was obtained by soaking the silica into HAuCl4 solution, drying and annealing at ⩽300 °C, without any special reduction treatment. Further experiments, revealed that the reducing groups OH on pore walls are responsible for reduction of Au3+ ions at low temperature. The formation of Au nanowires can be attributed to the low nucleation rate, uni-directional diffusion of Au atoms along pore channels and the size confinement of pore channels.

The Gibbs free energy of transfer of electrolytes from a reference solvent to the target solvent has been presented employing the Marcus–Saveant quadratic activation–diving force relationship. The electroreduction of carbon tetrachloride has been used as the probe reaction in 12 organic solvents, in which the parabolic variation of logarithmic heterogeneous electron transfer rate constant with potential has been observed in eight solvents. Using the standard electrode potentials for the reduction of carbon tetrachloride, the standard free energies of transfer of silver chloride from water to eight solvents have been estimated.

Theoretical study on the reaction mechanism of proton transfer in formamide by Ai-ping Fu; Hong-liang Li; Dong-mei Du; Zheng-yu Zhou (332-337).
We present detailed theoretical studies of the proton transfer in the isolated, mono, dehydrated forms and dimers of formamide and the effect of hydratation or self-assistance on the transition state structures corresponding to proton transfer from the keto form to the enol form, employing MP2 and B3LYP methods at varied basis sets. The barrier heights for both H2O-assisted and self-assisted reactions are significantly lower than that of the bare tautomerization reaction from formamide to formamidic acid, implying the importance of the superior catalytic effect of H2O, (H2O)2 and important role of NH2CHO for the intramolecular proton transfer.

The ν 5 band of CH3CD3: high-resolution spectrum and global three-band analysis by J.R. Cooper; A.R.W. McKellar; I. Ozier; N. Moazzen-Ahmadi (338-348).
The lowest frequency parallel fundamental band ν 5 of CH3CD3 near 900 cm−1 has been measured at low temperature with a resolution of 0.002 cm−1 using Fourier transform spectroscopy. The band is weak and an absorption path of 60 m was used. Large torsional splittings due to inter-vibrational coupling have been observed. Building on previous studies of the torsional levels in the ground vibrational state and in the methyl rocking state ν 12, a three-band analysis including these most recent data have been completed. The combined data set of almost 2 700 frequencies was fitted to within experimental accuracy using a 45-term model Hamiltonian. The results were found to bear a striking resemblance in most respects to those of an earlier, analogous study of CH3SiH3. In addition to the interactions described in that work, however, the present study indicates an important but local coupling between the (v 5=1,v 6=0) and (v 12=1,v 6=1) states of CH3CD3. This coupling has a strong effect on the K=7 lines of the ν 5 band, which have been successfully assigned and fitted here.

Quantum chemical calculations using the multi-state multiconfigurational MS-CASPT2 method, in conjunction with the 6-31G(d,p) basis set, have been applied to investigate the electronic structure of the parent diamino-meta-quinonoid molecule containing a six-membered carbon ring coupled with two exocyclic CO bonds situated in a meta position, along with two NH2 substituents. A particular attention has been paid to its electronic spectrum. Our results obtained using the MS-CASPT2 method do not agree with the recent CIS results by Sawicka et al. [Chem. Phys. Lett. 362 (2002) 527] on the identity of two observed UV absorption bands centered at 350 and 343 nm. A new interpretation on the origin of these bands is proposed.

Molecular dynamics simulations are used to examine the dissociation of halogen molecules that impact a surface at collision velocities up to 10 km/s. For iodine molecule, the yield of dissociation of vibrationally cold molecules saturates below 50%, although the center of mass energy is up to 80 times the bond energy. The origin of this phenomenon is the dissociation dependence on the collision angle. Two segments of collision angles are non-reactive due to deactivation of the internal energy, which happens before the atoms separated. The importance of the vibration phase to the dissociation process is also discussed.

Diameter-controlled multiwalled carbon nanotubes (MWNTs) have been grown by hot-filament chemical vapor deposition using nickel nanoparticles as catalyst. The nanoparticles were generated by laser ablation, classified with a differential mobility analyzer, and deposited onto silicon substrate. The particle size is tunable down to 2–3 nm, and particles with a geometric mean diameter of 5.1 nm (geometric standard deviation: 1.1) were used for carbon-nanotube growth. MWNTs were grown on the substrate using acetylene at 550 °C. The particles did not coalesce during growth, and the MWNTs had outer diameters matching the particle sizes, indicating that the current method can produce diameter-controlled MWNTs.

A method for constructing the Boltzmann–Gibbs distributions is presented by combining the re-weighting technique and the deterministic dynamical equation that produces the Tsallis distributions. The ability to produce the Boltzmann–Gibbs distributions is shown by calculating the distribution, the energy with higher moments, and the Helmholtz free energy. From numerical simulations of a small system that represents a fundamental chemical interaction model, correct answers were obtained within a wide range of temperatures. An application to a peptide system is also shown.

Preparation and structure of magnesium oxide coated indium nanowires by Chengchun Tang; Laure Bourgeois; Yoshio Bando; Dmitri Golberg (374-380).
Indium nanowires embedded in rectangular nanorods of MgO were synthesized by using the boron oxide-buffer catalytic growth method. The MgO nanorods were found to present a core of pure indium 15–20 nm in diameter. Electron diffraction analysis indicates that the embedded indium nanowires exhibit the tetragonal structure of pure indium and that the outer rectangular nanorods are face-centered cubic MgO. The orientation relationship between the indium and its MgO shell is determined to be ( 1 ̄  1 0) MgO //(1 0 0) In and (0 0 1) MgO //(0  1 ̄  1) In .

Formation process of single-walled carbon nanotubes by the catalytic chemical vapor deposition method is studied by molecular dynamics simulation. We start the calculation with randomly distributed carbon-source molecules and a nickel cluster to investigate the metal-catalyzed growth of a cap structure of a nanotube. When the catalytic cluster reaches saturation with carbon atoms, hexagonal networks are formed both inside and on the surface of the cluster, leading to their precipitation on the cluster’s surface and edges. An appropriate nanotube cap structure is generated when pieces of the hexagonal network structure extending from inside the cluster merges above the metal surface.

In the experiment on electron-stimulated positive-ion desorption, H+(NH3) n ions are ejected intensively from NH3 physisorbed on an Ar spacer layer, whereas fragmentation occurs preferentially for C2H6, C2H4, and C2F6 molecules. The ions are emitted efficiently via Coulombic fission of physisorbed ultrathin films of NH3, C2H6, and C2H4, but dissociative ionization is responsible for the ion emission from the C2F6layer. Moreover, molecular reactions are induced explosively by the electronic excitation of physisorbed ultrathin films: solvated protons or deuterons of formamide, ethyl amine, and ethyl alcohol, respectively, are ejected from CO/NH3, C2H6/NH3, and C2H6/D2O layers.

An enlarged basis Full-Cl calculation of C 7 dispersion coefficients for the LiH–LiH homodimer by Gian Luigi Bendazzoli; Antonio Monari; Valerio Magnasco; Giuseppe Figari; Marina Rui (393-398).
C 7 long-range dispersion coefficients for LiH–LiH are evaluated from Full-CI calculations of frequency-dependent dipole and dipole–quadrupole polarizabilities of ground state LiH at a few selected imaginary frequencies. The elementary dispersion constants are evaluated analytically from the Casimir–Polder integral using a recently proposed interpolation technique in its 2-term form which requires knowledge of just four polarizability values. The enlarged basis of 109 GTOs used in this work improves upon earlier results obtained by use of the smaller 58 GTOs basis set.

We discuss the possibility of controlling biological systems, by exciting in the near infrared region hybrid metallic nanotube ropes, dressed with proteins and embedded in the biosystems. If one nanotube, in a double-tube rope, is filled with metallofullerenes and the other is empty, the two tubes change their opposite equilibrium charging during the irradiation. The resulting change of the local electric field can deform proteins attached to the tubes, and change their catalytic properties.

Ultra-thin zeolite films prepared by spin-coating Silicalite-1 precursor solutions by A.M. Doyle; G. Rupprechter; N. Pfänder; R. Schlögl; C.E.A. Kirschhock; J.A. Martens; H.-J. Freund (404-409).
A procedure has been developed to prepare ultra-thin zeolite films supported on Si(1 0 0). Films were prepared by spin-coating a solution of Silicalite-1 zeolite precursors diluted in ethanol, followed by hydration in water vapour and heating to 60 °C. High resolution transmission electron microscopy analysis of sample cross-sections shows that the surfaces are both smooth and continuous, and films of approximately 2 and 15 nm thickness were prepared by varying the precursor dilution factor. Electron diffraction analysis shows that the 15 nm film is an amorphous arrangement of Silicalite-1 precursors. Atomic force microscopy measurements confirm that the surface is smooth over a range of several microns.

13C-detected 1H–2H separated local field NMR spectroscopy by S.V. Dvinskikh; D. Sandström; H. Zimmermann; A. Maliniak (410-417).
We present a new NMR method for measuring 1H–2H dipolar couplings in macroscopically oriented media. To overcome the lack of dipolar resolution in 1D 1H and 2H spectra of deuterated molecules, we use a 2D heteronuclear correlation experiment where 1H chemical shifts and 1H–2H dipolar interactions in the first dimension are correlated with 13C chemical shifts and 2H–13C dipolar interactions in the second dimension. The technique is demonstrated on a columnar liquid-crystalline phase.

Excitation energy dependence in the electronic dephasing time of the NO dimer by Masaaki Tsubouchi; Toshinori Suzuki (418-425).
The wavelength dependence of the electronic dephasing time in the optically excited state of the NO dimer has been measured by femtosecond pump–probe photoelectron imaging for the range of 200–235 nm. The observed dephasing time increased from 0.2 to 1 ps towards longer photoexcitation wavelengths. The 3s Rydberg state was formed with similar time constants for excitation wavelengths of λ<220 nm.

Solvation dynamics in DMPC vesicle in the presence of a protein by Partha Dutta; Pratik Sen; Saptarshi Mukherjee; Kankan Bhattacharyya (426-433).
Solvation dynamics of DCM is studied in DMPC vesicle in the presence of a protein, human serum albumin (HSA). In bulk water, solvation dynamics of DCM bound to HSA displays a 10 ns component. This component is absent when HSA is entrapped in the vesicle. This suggests that the protein does not undergo tumbling inside the vesicle. In the vesicle, solvation dynamics in the presence of HSA is slower compared to that in its absence. Solvation dynamics below the gel transition temperature (T c≈23 °C) is about two times slower than that above it.

Structure- and size-controlled ultrafine ZnS nanowires by X.M. Meng; J. Liu; Y. Jiang; W.W. Chen; C.S. Lee; I. Bello; S.T. Lee (434-438).
We report the first synthesis of ultrafine zinc sulfide (ZnS) nanowires with a sphalerite structure. Large-area, high- and uniform-density ZnS nanowires were grown on Au-coated silicon substrates by hydrogen-assisted thermal evaporation. The product was analyzed with scanning electron microscopy, X-ray diffraction, transmission electron microscopy and photoluminescence (PL). The ZnS nanowires had a sphalerite structure, a growth direction along [1 1 1], diameters of 10–20 nm, and lengths of several micrometers. The PL spectrum of the ZnS nanowires was measured. The growth of the ZnS nanowires was explained with the vapor–liquid–solid model, and their structure could be controlled by the deposition temperature.

Monodromy of the LiNC/NCLi molecule by M. Joyeux; D.A. Sadovskiı&#x0301;; J. Tennyson (439-442).
Using the potential surface of Essers, Tennyson, and Wormer in [Chem. Phys. Lett. 89 (1982) 223], we show that the system of bending vibrational states of the isomerizing molecule LiNC/NCLi has monodromy. On the basis of a deformed spherical pendulum model, we explain dynamical and geometric reasons of this phenomenon and of its absence in the similar system HCN/CNH.

Synthesis of large-scaled MoO2 nanowire arrays by Jun Zhou; N.S. Xu; S.Z. Deng; Jun Chen; J.C. She (443-446).
Large-scaled MoO2 nanowire arrays have been prepared on silicon substrates by thermal evaporation of Mo in a flow of argon gas without using any catalyst. The nanowires are well aligned and vertically oriented to substrate surface. The cross-section of most of the nanowires has a polygonal shape with the width of about 150 nm, and the typical lengths of the nanowires vary from 2 to 4 μm. The X-ray energy dispersive spectroscopy reveals that the nanowires contained elements of Mo and O. X-ray diffraction analyses and high-resolution transmission electron microscopy study show that the MoO2 nanowires are of monoclinic structure.

Incoherent broad-band cavity-enhanced absorption spectroscopy of azulene in a supersonic jet by Sven E. Fiedler; Gerald Hoheisel; Albert A. Ruth; Achim Hese (447-453).
The application of incoherent broad-band cavity-enhanced absorption spectroscopy (IBBCEAS) to isolated jet-cooled gas-phase species is demonstrated on basis of the S1  ← S0 transition of azulene in a continuous supersonic expansion. By focusing white light from a high power Xe-lamp into an optically stable resonator, which is intercepted by the supersonic seeded jet, the absorption is measured over a broad spectral range between 17 300 and 20 255 cm−1 with a resolution of ≈4 cm−1. The resolution, which is due to the dispersion of transmitted light by a grating monochromator, is sufficient to monitor the highly congested vibronic structure >3000 cm−1 above the S1,0 origin of azulene. The sensitivity required for this absorption experiment compares well to that of conventional pulsed cavity ring-down measurements.

Fast electron dynamics in small aluminum clusters: non-magic behavior of a magic cluster by Peter Gerhardt; Marco Niemietz; Young Dok Kim; Gerd Ganteför (454-459).
Relaxation dynamics of the optically excited state in Al n with n=6–15 were studied using time-resolved two photon photoemission spectroscopy. Relaxation rates of these Al clusters are slower than those of some d-metal clusters which can be explained by lower electron density of state in the sp-metals. The relaxation rate of Al13 , a magic cluster anion with a closed electronic shell is as fast as the non-magic clusters such as Al10 , implying that the relaxation dynamics of magic clusters cannot be rationalized by the electron–electron scattering. Origin of this unexpected behaviour of the magic cluster is discussed.

Ultrafast ligand exchange rates determined by ab initio QM/MM molecular dynamics by Christian F. Schwenk; Markus J. Loferer; Bernd M. Rode (460-465).
Free energies calculated from radial distribution functions supply information on ultrafast dynamics of solvated ions such as alkali and alkaline earth metal ions hardly accessible by current experimental techniques. Accurate computer simulations can thus be employed as suitable tool for reaction dynamics in the femtosecond and picosecond timescale, and they even allow to clearly distinguish between different ligands in mixed solvates, which is a most difficult task in experiment.

Density functional theory was used to study the hydrogen bonding between the water and the ClO radical. The two energetically low-lying minima are 5 (2A) and 6 (2A), with hydrogen bonding occurring between the chlorine atom in the ClO radical and the hydrogen atom in the water; the 2A state has a slightly (∼0.3 kcal/mol) lower energy. Another hydrogen bond occurs between one of the hydrogen atom in the water and oxygen atom in the ClO radical. The optimized geometry parameters, rotational constants and interaction energies for various isomers were calculated at the UB3LYP and UMP2 levels. The infrared spectra and the vibrational frequency shifts are also reported.

Controlling the orientation of polar molecules by half-cycle pulses by A. Matos-Abiague; J. Berakdar (475-480).
We study the quantum dynamics of a linear polar molecule subjected to electromagnetic pulses. For a sequence of half-cycle pulses we derive, from a simplified analytical model, conditions to induce a molecular orientation sustainable for hundreds of picoseconds. The predictions are confirmed by full numerical calculations for the molecule NaI. Analyzing the effect of finite temperatures we conclude that the process of maintaining the molecular orientation is robust to the thermal average.

Spectroscopic properties of Yb3+ in bismuth borate glasses by Yujin Chen; Yidong Huang; Zundu Luo (481-488).
Absorption spectra, fluorescence spectra and fluorescence decay curves have been measured at room temperature. Spectroscopic and laser performance parameters of Yb3+ in bismuth borate glasses with different compositions and Yb3+ concentrations were calculated. The effects of the host glasses compositions and Yb3+ concentration on the spectroscopic and laser performance parameters have been analyzed. The effect of radiation trapping on the spectroscopic properties has also been discussed. The results show that the Yb3+-doped bismuth borate glass is a promising laser material.