2006 Vol. 19, No. 1

Letter
Happy New Year!
As many of you are aware that Chinese science is at the crucial stage of development. We are now seeing more and more high quality works being produced by Chinese scientists working in China. However, high quality scientific works are rarely published in Chinese scientific journals so far. Therefore, the development of scientific journals publishing in China now becomes a more and more important indication of the science development in China.
In the development of the chemical physics research field in China, the Chinese Journal of Chemical Physics (CJCP) has made significant contributions in the past 18 years. Since CJCP is primarily a Journal published in Chinese previously, its impact in the international scientific community has been quite limited. At this moment, we believe CJCP should increase its impact in the international community. We believe that making CJCP an English journal is a crucial step to increase its in°uence internationally. Therefore, upon the recommendation of senior editorial members, we now change CJCP into an full English journal from this issue on. We have also formed a high quality editorial board to help the editorial matters in CJCP, and a prestigious advisory board to advise us of the future development. I am very honored to be selected as the new Editor-in-Chief for the next four years. I hope by the end of my term, the impact of this journal is significantly improved through the efforts of our editorial team.
Building a high quality scientific journal is not an easy task. I hope that every member of our chemical physics community can provide strong support to this journal by sending your high quality research papers in the future. We are also thinking about adding new sections of this journal to attract more readers. With the support of our community, I am confident that we can make this journal a more successful one.
Here, I want to take this opportunity to thank the great leadership provided by the Editor-in-Chief since the foundation of this journal, Professor Nan-quan Lou, who has just become a senior advisory board member of this journal. I also want to thank the senior associate editor, Prof. Shu-qin Yu, who has made great contributions to the development of CJCP. Many thanks also go to the other senior associate editors, Profs. Die-yan Chen, Hai-lung Dai, Xing-xiao Ma, Han-qing Wang, Hou-wen Xin, Cun-hao Zhang and Qi-he Zhu, who have made important contributions to CJCP in the past 18 years.
We plan that CJCP will soon become available online so that members of our community can access this journal easily through internet. This will also help us to provide greater visibility of this journal in the international research community.
Xue-ming Yang
Editor-in-Chief
February 12, 2006
Article
Photodissociation dynamics of ketene at 218 nm has been investigated using the velocity map ion-imaging method. Both angular and translational energy distributions for the CO products at different rotational and vibrational states have been obtained. The 2+1 REMPI spectrum of CO products is also obtained. The results are as bellow: (i) CO products in the first two vibrational states ( v”=0 and v”=1 ) exhibit signiffcant rotational excitation. Furthermore the rotational excitation of CO at the v”=0 level is noticeably higher than that at the v”=1 level. (ii) It was found that the major photodissociation pathway of ketene at 218 nm is the CH2(a1A1)+CO(X1Σ+) channel, while the CH2(b1B1)+CO(X1Σ+) channel and the CH2 (X 3B1)+CO(X1Σ+) channel are also likely present. (iii) The anisotropy parameters b of CO different rovibronic states all appear to be larger than zero. No significant difference is observed at the two vibrational states. 30 Refs. In English
The excited state of Chlorophyll a is investigated by femtosecond transient absorption. The transient absorption spectra of Q band and By band of Chlorophyll a in ethanol have been observed. The fast kinetics of Chlorophyll a which exhibit two ultrafast components were also measured. The one is assigned to transient absorption of the inhomogeneously broadened ground state absorption spectrum, while the other is the response of the solvent to the change of the electron configuration in the excited state due to salvation dynamics of the polar solvent molecules. To understand the anisotropy of Chlorophyll a in ethanol, the anisotropy profile was also performed by 405 nm excitation and found that the anisotropy profile is 0.143. The possible combination of θda, θdb and η at excitation of By band has been simulated.
Sixty-five new vibronic levels of the Na2 43Σ+g state have been observed in the 33900-35200 cm-1 energy region above the potential minimum of the ground state by pulsed perturbation facilitated optical-optical double resonance (PFOODR) fluorescence excitation spectroscopy. These new data fill the gap between the low-v levels mainly observed by continuous wave (CW) PFOODR spectroscopy and the high-v levels above the 3s+3d limit observed by pulsed PFOODR with predissociation detection. Molecular constants are fitted below potential shelf around the 3s+3d atomic limit with previously published data (mainly observed by CW PFOODR) and these new data. RKR potential curve has been calculated with the new constants. The constants are: Te = 32127:090 cm-1, we = 121:4099(0:20720) cm-1, Be = 0:116287(0:0002300) cm-1, Re =3:551 ?. An error of the RKR potential curve of J. Chem. Phys. 108, 7707 (1998) is corrected.
Infrared absorption spectra of gaseous CH2Cl2 in the regions of 1200-12000 cm-1 were measured using a Bruker IFS 120HR Fourier transform spectrometer in conjunction with a multipass cell. 47 vibrational levels of overtone and combinational spectral lines of the CH stretching (v1, v6), bending (v2), and rocking(v8) modes were analyzed and assigned. Utilizing the normal mode model and considering the coupling among CH stretching, bending and rocking vibrations, values of the harmonic frequency ωi, the anharmonic constant xij, and the coefficients of Fermi and the Darling-Dennison resonances of v1, v6, v2 and v8 modes were also determined from experimental spectral data with nonlinear least-square fitting. These spectral constants reproduced the experimental levels very well. These results showed that Fermi resonance between CH stretching and rocking vibrations (ki88=-254.63 cm-1) is stronger than that between CH stretching and bending vibrations (k122 = 54.87 cm-1); and that Darling-Dennison resonances between CH stretching and bending vibrations (k1166=-215.28 cm-1) is also much stronger than that between CH bending and rocking vibrations (k2288=-5.72 cm-1).
Here we report a quantitative study of the orientational structure and motion of water molecule at the air/water interface. Analysis of Sum Frequency Generation (SFG) vibrational peak of the free O-H stretching band at 3700 cm-1 in four experimental configurations showed that orientational motion of water molecule at air/water interface is libratory within a limited angular range. The free OH bond of the interfacial water molecule is tilted around 33° from the interface normal and the orientational distribution or motion width is less than 15°. This picture is significantly different from the previous conclusion that the interfacial water molecule orientation varies over a broad range within the ultrafast vibrational relaxation time, the only direct experimental study concluded for ultrafast and broad orientational motion of a liquid interface by Wei et al.(Phys. Rev. Lett. 86, 4799, (2001)) using single SFG experimental configuration.
The allyl radical has been observed in a low-pressure premixed gasoline/oxygen/argon flame by using tunable vacuum ultraviolet photoionization mass spectrometry. The ionization potential of the allyl radical is derived to be (8.13 + 0.02) eV from photoionization efficiency curve. In addition, a high level ab initio Gaussian-3(G3) method was used to calculate the energies of the radical and its cation. The calculated adiabatic ionization potential is 8.18 eV, which is in excellent agreement with the experimental value. The result is helpful for identifying the allyl radical formed from other flames and for understanding the mechanism of soot formation.
The ionization energies (IEs) of cyclopropenylidene (c-C3H2), propargylene (HCCCH) and propadienylidene (H2CCC) have been computed using the CCSD(T)/CBS method, which involves the approximation to the complete basis set (CBS) limit at the coupled cluster level with single and double excitations plus quasi-perturbative triple excitation effect (CCSD(T)). The zero-point vibrational energy correction,the core-valence electronic correction, the scalar relativistic effect and the high level correction beyond the CCSD(T) excitations have also been made in these calculations. The CCSD(T)/CBS values for the IE(c-C3H2) and IE(HCCCH) of 9.164, 8.987 eV are in good agreement with the experimental values of (9.15±0.03) and (8.96±0.04) eV. The CCSD(T)/CBS calculations yield the IE values of 10.477 and 10.388eV for the ionization transitions H2CCC→H2CCC+(2A1, C2v) and H2CCC→H2CCC+(2A', Cs), respectively. On the basis of the Franck-Condon factor consideration, the IE of (10.43±0.02) eV determined in the previous single-photon ionization experiment most likely corresponds to the ionization threshold for the H2CCC→H2CCC+(2A1, C2v) transition. Although the precision of the experimental IE measurements for c-C3H2, HCCCH, and H2CCC is insufficient to pin down the accuracy of the theoretical calculations to better than ±30 meV, the excellent agreement between the experimental and theoretical IE values observed in the present study indicates that the CCSD(T)/CBS calculations together with high-order correlation corrections are capable of yielding reliable IE predictions for simple hydrocarbon carbenes and bi-radicals.We have also reported the heats of formation at 0 K (ΔHof0) and 298 K (ΔHof298) for c-C3H2/c-C3H2+,HCCCH/HCCCH+, and H2CCC/H2CCC+. The available experimental ΔHof0 and ΔHof298 values for c-C3H2/c-C3H2+, HCCCH/HCCCH+ are found to be in good accord with the CCSD(T)/CBS predictions after taking into account the experimental uncertainties.
A graphically oriented interactive program for assignments of rotationally resolved molecular spectra has been devised. The program functions by grouping spectral lines in term of the second difference principle,and graphing spectral intensity versus frequency in a bar graph of the selected groups, distinguished by color and/or line-type. This allows for easy detection of regular patterns buried in the observed spectrum.Furthermore, it includes a Loomis-Wood view for assisting in spectral assignments. As an example, the program was applied in assigning the molecular spectrum of the production in the discharge of PCl3 buffered by helium gas, which may belong to several species. The results suggest that the program is highly efficient and quite useful in the assignment and the analysis of molecular spectra, especially those of symmetric top,slightly asymmetric top and linear molecules. The accuracy and efficiency of this program will likely ensure its wide application in the processing of molecular spectra.
The vibrational levels and potential energy surface of a stable structure for S2O in the excited electronic states C1A' were carried out with algebraic method. The vibrational spectra were obtained (with total quantum number v=20) by fitting 30 spectra data. The fitted rms(root mean square) error based on the Hamiltonian with 9 parameters was 2.40 cm-1. The dissociation energy and force constant were also determined by the analytical potential energy surface. The method is proved to be effective by comparing these results with the experimental data.
An analysis of the response of surface acoustic wave sensors coated with polymer film based on new coating deposition (self-assemble and molecularly imprinted technology) is described and the response formulas are hence deduced. Using the real part of shear modulus, the polymer can be classified into three types: glassy film, glassy-rubbery film and rubbery film. Experimental results show that the attenuation response is in better consistence with the simulation than in Martin's theory, but the velocity response does not accord with the calculation exactly. Maybe it is influenced by the experimental methods and environment. In addition, simulations of gas sorption for polymer films are performed. As for glassy film, the SAW sensor response increases with increasing film thickness, and the relationship between the sensor response and the concentration of gas is pretty linear, while as for glassy-rubbery film and rubbery film, the relationship between the sensor sensitivity and concentration of gas is very complicated. The ultimately calculated results indicate that the relationship between the sensor response and frequency is not always linear due to the viscoelastic properties of the polymer.
The interaction of atomic oxygen with the clean Cu(100) surface has been studied by means of cluster and periodic slab models density functional theory in the present paper. The Cu(4,9,4) cluster and a three-layer slab with c(2×2) structure are used to model the perfect Cu(100) surface. Three possible adsorption sites,top, bridge and hollow site, were considered in the calculations. The predicted results show that the hollow site is the prefer site for atomic oxygen adsorbed on Cu(100) surface energetically. This is in good agreement with the experiment. The calculated binding energies are respective 2.014, 3.154 and 3.942 eV for top, bridge and hollow sites at mPW1PW91/LanL2dz level for the cluster model. The geometry of Cu(100) surface has also been optimized theoretically with various density functional methods and the results show that the prediction from the B3PW91/LanL2dz and mPW1PW91/LanL2dz reproduce the experimental observation.The frontier molecular orbitals and partial density of states analysis show that the electron transfer from the d orbital of substrate to the p orbital of the surface oxygen atom.
According to the structure features of Fe80P20, A series of clusters Fe4P were designed and focused on studying the stability of local structure, charge distribution and chemical bond. Using the DFT method,energy and structure of Fe4P clusters were optimized and analyzed. The computational results showed that the energy of cluster 1(2) has the lowest energy, and the possibility of its existence in the Fe8oP20 is high. Analyzing the transition states among the clusters, it was found that the clusters in the doublet state are more stable than those in the quartet state. The numbers of the Fe-P bond in the clusters play important roles in the cluster stability and electrons transfer properties. The more numbers of Fe-P bonds in the clusters, the higher the cluster stability, and the weaker the ability of P atom to get electron. The number of Fe atoms, which has bonding interactions with the P atom, is direct proportional to the average 3d orbit population of Fe atom. Basing on the orbital population, average magnetic moments of each Fe atom in the Fe4P clusters were calculated, and they are all smaller than that of single metal Fe atom. This suggests that all Fe4P clusters have soft magnetic property and they are expected to be perfect material for preparing soft magnetic apparatus.
The equation of state of MgSiO3 perovskite under high pressure and high temperature is simulated using the molecular dynamics method. It was found that the molecular dynamics simulation is very successful in accurately reproducing the measured molar volumes of MgSiO3 perovskite over a wide range of temperatures and pressures. The simulated equation of state of MgSiO3 perovskite matched experimental data at up to 140GPa at 300 K, as well as the fitting data of others and results from the first-principles simulation based on the local density approximation. The simulated equations of state of MgSiO3 perovskite at higher temperatures and higher pressures also correspond to the other calculations. In addition, the volume compression data of MgSiO3 perovskite is simulated up to 120 GPa at 300, 900, 2000 and 3000 K, respectively.
In order to have efficient and highly stereoselective cyclopropanating reagents, the cyclopropanation reaction of ethylene promoted with Samarium(Ⅱ) carbenoid [Simmons-Smith(SS)reagent] were studied by means of B3LYP hybrid density functional method. The geometries for reactants, transition states and products are completely optimized. All transition states were verified by the vibrational analysis and the intrinsic reaction coordinate (IRC) calculations. The results showed that, identical with the lithium carbenoid,CH3SmCH2X(X=Cl, Br and I) can fairly react with ethylene via both methylene transfer pathway (pathway A) and carbometalation pathway (pathway B). And the cyclopropanation reaction via methylene transfer pathway proceeds with a lower barrier and at lower temperatures.
Semi-empirical AM1 method was used to study 1:1 and 1:2 hydrogen bond complexes formed with perylene dianhydride and pyridine derivatives. The weak interaction energy become bigger as the number of hydrogen bonds increases. The donor groups on the host and electron-withdrawing groups on the guest molecules favor hydrogen bonding interactions, and the formation of hydrogen bonding leads to electron density flow from the host to the guest molecules. Electronic spectra of these complexes were computed using INDO/SCI method. Blue-shift of the electronic absorption spectra for the complexes, comparing that of the host,takes place, and the first peaks for different complexes changed slightly. These are in agreement with the experimental results. The cause of blue-shift was discussed, and the electronic transitions were assigned based on theoretical calculations. The potential curve of double proton transfer in the complex was calculated, and the transition state and activated energy relative to the N-H bond were obtained.
Well-aligned open-ended multi-walled carbon nanotube (MWCNT) arrays were prepared via chemical vapor deposition (CVD) method in porous anodic aluminum oxide (AAO) templates without depositing any transition metals as catalyst. Effects of the CVD temperature and heat treatment were studied in detail.Well-aligned open-ended MWCNT arrays were obtained at the CVD temperature above 600 ℃; when CVD temperature is reduced to around 550 ℃, CNTs, CNFs and other structures existed at the same time; no CNTs or carbon nanofibres (CNFs) could be found as the CVD temperature is below 500 ℃, and only amorphous carbon in the porous AAO template was found. Experimental results showed that the AAO template is catalytic during the CVD process, and it has the following two effects: to catalyze thermal decomposition of acetylene and to catalyze conversion of carbon decomposed from acetylene into CNTs or CNFs. Heat treatment could improve the graphitization degree, but it might also introduce new defects.
An efficient and environmentally friendly procedure for the one-pot synthesis of 13-acetyl-9-methyl-11-oxo-8-oxa-10,12-diazatricyclo[7.3.1.02,7]trideca-2,4,6-triene from salicylaldehyde, acetylacetone and urea via Biginelli condensation and intramolecular Michael-addition by using magnesium bromide as an inexpensive and easily available catalyst in a solvent-free condition is described. The structural elucidation of the product is reported by 1H- and 13C-NMR spectra. The product can also be identified by its EI TOF mass spectrometry based on the molecular ion at m/s 246(10%) and on the fragment ions in which two nitrogen atoms are remained. Three kinds of characteristic fragmentation pathways from the molecular ion were observed. One is the loss of the OH radical to form the dihydropyrimidinone cation at m/z 229(48%), followed by elimination of a molecular methane forming the pyrimidinone cation at m/z 213(27%). The second is the cleavage of the C6H4OH radical, and the formation of the dihydropyrimidinone cation at m/z 153(24%). The third one is the loss of MeC=O radical to afford the oxygen-bridged fragment ion at m/z 203(33%).
The inclusion-complex of CD-MCP (β-cyclodextrin (β-CD) including 1-methylcyclopropene (1-MCP)) was prepared and characterized. Basing on programmed-heating procedure and weight-temperature analysis, as well as the application of Satava- Sestak's, Ozawa's and Kissinger's methods, the mechanism and kinetics of thermal dissociation of this inclusion complex were studied. An additional mass loss is found at 170-180 ℃.The mechanism of thermal dissociation of CD-MCP is dominated by a one-dimensional random nucleation and subsequent growth process (A2/3). The activation energy ES and the pre-exponential factor As for the process are 102.14 kJ/mol and 3.63×1010 s-1, respectively. This Es value shows that there is no strong chemical interactions betweenβ-CD and 1-MCP.