Sheng Liu-Si

Anion Mass Spectrometry Study of Ion-Pair Photodissociation of CO2 in the XUV Energy 19.70?22.24 eV

We demonstrate anion mass spectrometry using the Hefei synchrotron radiation source to investigate the ion-pair dissociation processes of molecules. The efficiency curve of the O− anionic product via ion-pair dissociations of CO2 is recorded with tunable extreme vacuum ultraviolet photons (energy: 19.70–22.24 eV) and compared with the spectrum available in the literature. The possible dynamics of CO2 + hv → CO+ + O− in this energy range is discussed.

Theoretical and experimental study of aluminum ion–acetonitrile clusters

Abstract The gas phase reactions between a singly charged aluminum ion and acetonitrile clusters are studied by a laser ablation-molecular beam method. Similar to metal ion–methanol clusters, two distinct intensity gaps of Al+(CHCN)n clusters are found. The first intensity gap occurs between n=4 and n=5, and the second is found between n=6 and n=7. Density functional calculations on the structures and energetic of the reactants and products are carried out at the B3LYP/6-31+G ∗ level in order to get a qualitative picture about the gross geometries and thermodynamic stability. For ionic clusters Al+(CHCN)n, there are two kinds of stable isomers. As the size of the cluster increases from two to four, the relative stability decreases gradually. According to the results of experiments, the signal intensity of clustered complex ions decreases with the size of the cluster increase from two to four. Good agreement between theory and experiment is found for ionic clusters Al+(CHCN)n.

Photodissociation Efficiency Spectroscopy Study of the Rydberg Excited Ion-Pair States of Carbon Dioxide

Photodissociation efficiency spectrum of anionic oxygen atom produced via ion-pair dissociations of carbon dioxide is recorded by means of the synchrotron radiation excitation (XUV photon energy 17.40–20.00 eV). The present spectrum is assigned as the Rydberg-like excited ion-pair states, i.e., Tanaka–Ogawa and Henning series, 2Σg+ (CO+2) vibrational ground-state and excitation series. Three Rydberg series, npσu, npπu, and nfu, converging to 2Σg+ (0, 0, 0), show the higher cross sections.

The UV induced fluorescence inPorites coral from Hainan Island, China and its paleo-environmental implications

Porites coral in the nearshore waters off Hainan Island can give off yellowish-green fluorescence under UV laser induction. After fitting the data between rainfall and fluorescent intensity, it can be found that both appear in a simply linear equation with a correlation coefficient of 0.78. The model equation can be used to reconstruct the rainfall in the past time by means of the determined fluorescent intensity. The correlation diagram of the determined and calculated or hindcast rainfall shows a synchronous change from 1982 to 1997. The peak positions of the variant curve are usually related to the El’nino year. That means the drought and flood recycles are restrained to some extent by globally environmental changes. Therefore, the coral fluorescent intensity acts as a geochemical proxy for reconstructing the rainfall series in the past hundreds of years and predicting the drought-flood variant tendency in the future time.

Three-dimensional stress distribution of surplus assembled 7050Al alloy ring and plug determined by neutron diffraction

The hoop, radial and axial stress and strain distribution of surplus assembled 7050Al alloy ring and plus were investigated by neutron diffraction method. The measured results from crystal planes (200) and (311) are coincided with the data obtained by analytical calculation and international standard sample experiment. The discontinuous stress and strain at the interference of ring and plug can be clearly shown by the neutron diffraction method. Monte Carlo method was used to simulate the neutron diffraction process to reduce the deviation of the stress at the surface. The results show that the measured accuracy can be improved when the slits are substituted by the radial collimation. Compared the results obtained from (311) and (200) with analytical calculation, it reveals that the stress distribution among crystal planes will cause system deviation. Therefore the experiment accuracy may be further improved if the inner plane stress could be evaluated. The results also indicate that the strain accuracy will be affected by microstress and texture, and the gauge volume should be reduced as small as possible at the region where the stress distribution is steep.

The Measurement of the Ionization Potential and the Bond Energy Si(CH 3 ) 2 Cl 2

The vacuum ultraviolet photoionization spectrum of Si(CH3)(2)Cl-2 has been obtained with synchrotron radiation source. The adiabatic ionization potential of Si(CH3)(2)Cl-2 is 10.62 +/- 0.03eV (0.37eV lower than reported by PES), and the appearance potentials for Si(CH3)Cl-2(+), Si(CH3)(2)Cl+, SiCH3+ and SiCl+ are 11.25 +/- 0.03eV, 12.69 +/- 0.04eV, 15.1 +/- 0.1eV and 21.16eV +/- 0.1eV respectively. From these results, we estimate D(Si(CH3)Cl-2(+)-CH3)=0.63 +/- 0.03eV and D(Si(CH3)(2)Cl+-Cl))=2.07 +/- 0.04eV.