ECR离子源高电荷态金属离子产生的MIVOC法实验研究

为满足兰州重离子加速器的实验要求,先后在中国科学院近代物理研究所14.5GHz(LECR2)及10GHz+14.5GHz(LECR3)高电荷态ECR离子源上使用MIVOC(Metallic ion fromvolatile compounds)方法进行了高电荷态金属离子产生的实验研究。主要研究了铁和镍的各种高电荷态离子的产生,具有代表性的是210eμA的Fe11+、175eμA的Fe12+、142eμA的Fe13+、25eμA的Fe16+、64eμA的Ni10+、57eμA的Ni13+、31eμA的Ni15+和15eμA的Ni16+。本文将分别给出两种金属离子产生的多电荷态束流谱图,并对实验装置的安排、实验现象及结果进行讨论与总结。

Enhanced biological effect induced by a radioactive C-9-ion beam at the depths around its Bragg peak

To explore the potential of double irradiation source, radioactive C-9-ion beam, in tumor therapy, a comparative study oil the surviving effect of human salivary gland cells at different penetration depths between C-9 and C-12-ion beams has been carried out. The 9C-ion C beam, especially at the distal side of the beam came out more efficient in cell killing at the depths around its Bragg peak than the 12 Bragg peak. Compared to the C-12 beam, an increase in RBE by a factor of up to 2.13 has been observed at the depths distal to the Bragg peak of the 9C beam. The 9C beam showed an enhanced biological effect at the penetration depths around its Bragg peak, corresponding to the stopping region of the incident C-9-ions and where the delayed low-energy particles were emitted. Further analysis revealed that cell lethality by the emitted particles from the stopping C-9-ions is responsible for the excessive biological effect at the penetration depths around the Bragg peak of the C-9 beam.

Photo-induced reactions in the ion-molecule complex Mg+-OCNC2H5

Ion - molecule complexes of magnesium cation with ethyl isocyanate were produced in a laser- ablation supersonic expansion nozzle source. Photo- induced reactions in the 1: 1 complexes have been studied in the spectral range of 230 - 410 nm. Photodissociation mass spectrometry revealed the persistent product Mg+ from nonreactive quenching throughout the entire wavelength range. As for the reactive channels, the photoproducts, Mg+OCN and C2H5+, were produced only in the blue absorption band of the complex with low yields. The action spectrum of Mg+(OCNC2H5) consists of two pronounced peaks on the red and blue sides of the Mg+ 3(2)P <-- 3(2)S atomic transition. The ground state geometry of Mg+ - OCNC2H5 was fully optimized at B3LYP/6- 31 - G** level by using GAUSSIAN 98 package. The calculated absorption spectrum of the complex using the optimized structure of its ground state agrees well with the observed action spectrum. Photofragment branching fractions of the products are almost independent of the photolysis photon energy for the 3P(x,y,z) excitations. The very low branching ratio of reactive products to nonreactive fragment suggests that evaporation is the main relaxation pathway in the photo- induced reactions of Mg+ (OCNC2H5). (C) 2003 American Institute of Physics.

Structural analysis of monoterpene glycosides extracted from Paeonia lactiflora Pall. using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry and high-performance liquid chromatography/electrospray ionization tandem mass spectrometry

Paeoniflorin standard was first investigated by electrospray ionization Fourier transform ion cyclotron resonance tandem mass spectrometry (ESI-FTICR-MS/MS) using a sustained off-resonance irradiation (SORI) collision-induced dissociation (CID) method at high mass resolution. The experimental results demonstrated that the unambiguous elemental composition of product ions can be obtained at high mass resolution. Comparing MS/MS spectra and the experimental methods of hydrogen and deuterium exchange, the logical fragmentation pathways of paeoniflorin have been proposed. Then, the extracts of the traditional Chinese medicine Paeonia lactiflora Pall. were analyzed by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS). By comparison with the ESI-FTICR-MS/MS data of paeoniflorin, the isomers paeoniflorin and albiflorin in Paeonia lactiflora Pall. have been identified using HPLC/MS with CID in an ion trap and in-source CID. Furthermore, using the characteristic fragmentation pathways, the retention times (t(R)) in HPLC and MS/MS spectra, the structures of three other kinds of monoterpene glycoside compounds have been identified on-line without time-consuming isolation.

Facile synthesis and photoluminescence of europium ion doped LaF3 nanodisks

LaF3 : Eu3+ (5.0 mol-% EU3+) nanodisks with perfect crystallinity were successfully synthesized by a simple method. The synthesis was carried out in an aqueous solution at room temperature without the use of templates or organic additives, The mechanism of formation of the nanodisks was explored, and the fluoride source (KBF4) is believed to play a key role in controlling the morphology of the final product. Furthermore, the size of the disk can be simply moderated by varying the concentration of the initial reactants. The room-temperature photoluminescence of LaF3 : Eu3+ with different morphologies and sizes were also investigated, and the results indicate that the emission intensity of the product is strongly affected by their size, shape, and other factors.

Positive- and negative-ion matrix-assisted laser desorption/ionization mass spectrometry of saccharides

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) of oligosaccharides and polysaccharides has been investigated in detail, It is demonstrated that cationized species of oligosaccharides, [M+Na](+) and [M+K](+), are dominant products under the MALDI condition, and negative ions of oligosaccharides are not formed to any significant extent in this process, The molecular masses of polysaccharides are similarly determined by positive- and negative-ion MALDI-MS with the help of column chromatography. The distinction between positive- and negative-ion MALDI mass spectra of oligo-and polysaccharides indicates that the MALDI processes for saccharides vary with molecular mass. The matrix plays a more important role in the ionization process for oligosaccharides, while in the desorption process for polysaccharides. (C) 1998 John Wiley & Sons, Ltd.

A study of ion kinetic energy spectrometry of o(-), m(-), and p(-) diol benzene doubly charged ions and singly charged ions in gas phase

With Mass Analyzed Ion Kinetic Energy Spectrometry (MIKES), Collisional Induced Dissociation(CID), and Electron Capture Induced Decomposition(ECID) technigues, the doubly charged ions and singly charged ions from o(-), m(-), and p(-) diol benzene in the EI source have been studied. In terms of the values of the kinetic energy releases(T) of the charge separation reactions of the doubly charged ions and the estimated intercharge distances(R) of the exploding doubly charged ions the transition structures were proposed. Some structural information about the transition states was also obtained. It is of interest that the MIKES/CID spectra of singly charged ions [C6H6O2](+) from the three isomers are of significant differences.