Valence compounds versus metals. Synthesis, characterization, and electronic structures of cubic Ae(4)Pn(3) phases in the systems Ae = Ca, Sr, Ba, Eu; Pn = As, Sb, Bi

The isostructural compounds Sr(4)Bi(3), Ba(4)Bi(3), and Ba(4)As( approximately )(2.60) were prepared by direct reactions of the corresponding elements and their structures determined from single-crystal X-ray diffraction data as anti-Th(3)P(4) type in the cubic space group I43d, Z = 4 (a = 10.101(1) A, 10.550(1) A, 9.973 (1) A, respectively). The two bismuth compounds are stoichiometric, and the arsenide refines as Ba(4)As(2.60(2)). Only unrelated phases are obtained for all binary combinations among the title components for either Ca or Sb. The magnetic susceptibility and resistivities of Ba(4)Bi(3) and Eu(4)Bi(3) show that they are good metallic conductors ( approximately 40 microomega.cm at 298 K), whereas Ba(4)As(2.60) exhibits rho(150) > 1000 microomega.cm. The electronic structures of Sr(4)Bi(3), Ba(4)Bi(3), and Ba(4)As(3) were calculated by TB-LMTO-ASA methods. Mixing of cation d states into somewhat disperse valence p bands on Bi results in empty bands at E(F) and metallic behavior, whereas the narrower valence band in the electron-deficient Ba(4)As(3) leads to vacancies in about 11% of the anion sites and a valence compound.     

Synthesis, composition, and structure of sillenite-type solid solutions in the Bi2O3-SiO2-MnO2 system

Individual compounds and solid solutions are obtained under hydrothermal conditions in the Bi(2)O(3)-SiO(2)-MnO(2) system in the form of faceted crystals and epitaxial films on the Bi(24)Si(2)O(40) substrate. The crystals have the shape of a cube (for the molar ratio of the starting components Na(2)SiO(3)·9H(2)O:Mn(NO(3))(2)·6H(2)O > 1), a tetrahedron (for Na(2)SiO(3)·9H(2)O:Mn(NO(3))(2)·6H(2)O < 1), or a tetrahedron-cube combination (for Na(2)SiO(3)·9H(2)O:Mn(NO(3))(2)·6H(2)O = 1). Crystal-chemical analysis based on the data of single-crystal and powder X-ray diffraction, IR spectra, and the results of calculation of the local balance by the bond-valence method reveals formation of the Bi(24)(Si(4+),Mn(4+))(2)O(40) phases, which probably include Mn(5+) ions (epitaxial films), as well as the Bi(24)(Si(4+),Bi(3+),Mn(4+))(2)O(40) and Bi(24)(Si(4+),Mn(4+))(2)O(40) phases in the (1 - x)Bi(3+)(24)Si(4+)(2)O(40) - x(Bi(3+)(24)Mn(4+)(2)O(40)) system and the Bi(24)(Bi(3+),Mn(4+))(2)O(40) phase in the (1 - x)Bi(3+)(24)Bi(3+)(2)(O(39)?(1)) - x(Bi(3+)(24)Mn(4+)(2)O(40)) system. Precision X-ray diffraction studies of single crystals of the Bi(24)(Bi,Si,Mn)(2)O(40) general composition show that these sillenites crystallize in space group P23 and not I23 as the Bi(24)Si(2)O(40) phase. The dissymmetrization of sillenite phases is observed for the first time. It is explained by a kinetic (growth) phase transition of the order-disorder type due to population of a crystallographic site by atoms with different crystal-chemical properties and quasi-equilibrium conditions of crystal growth in the course of a hydrothermal synthesis below 400 °C at unequal molar amounts of the starting components in the batch.     

Selective Oxidation of Glucose to Gluconic Acid over Bimetallic Pd–Me Catalysts (Me = Bi,Tl, Sn,Co)

Catalytic properties of bimetallic Pd–Bi, Pd–Tl, Pd–Sn, and Pd–Co catalysts supported on C (from plum stones) and SiO₂ were studied in the reaction of glucose oxidation to gluconic acid. Catalysts modified with Bi show the best selectivity and activity. The results obtained from research on 5% Pd–5% Bi/C and 5% Pd–5% Bi/SiO₂ catalytic systems were compared with the results for a commercial catalyst containing 1% Pt–4% Pd–5% Bi supported on active carbon (Degussa). For both Pd–Bi/support catalysts and 1% Pt–4% Pd–5% Bi/C, similar selectivity in the reaction of glucose oxidation was observed. XRD studies proved the presence of intermetallic compounds BiPd and Bi₂Pd, which probably increase the selectivity of PdBi/SiO₂ catalysts.     

预还原氢化物发生—原子荧光光谱法快速测定化探样品中的As,Sb,Bi,Hg

通过对化探样品进行王水密闭溶解,饱和的硫脲-抗坏血酸预还原,运用氢化物发生-原子荧光光谱法实现了地质样品中As、Sb、Bi、Hg元素的任意配对以及连续快速测定。实验确定了原子化器高度为14mm,最佳溶样时间为1h。在优化条件下,结果显示还原剂(硫脲-抗坏血酸)对Hg、Bi测定结果无影响,且Hg、Bi测定结果在预还原20min至48h内都很稳定,测定结果良好,Cu、Co、Ni、Au、Ag、Cd、As、Sb、Bi、Se、Ge等金属离子对预还原测定汞均无干扰,对比实验表明还原剂体系下汞荧光强度值基本不变。方法的检出限低、精密度好、准确度高、操作简便,有效避免了元素污染问题,可满足大批量地质样品分析测定的需要。     

Structure and physical properties of ternary rare-earth cobalt bismuth intermetallics (RE)12Co5Bi (RE = Y, Gd, Tb, Dy, Ho, Er, Tm)

The rare-earth intermetallic compounds (RE)12Co5Bi (RE = Y, Gd, Tb, Dy, Ho, Er, Tm) were prepared by arc-melting and annealing at 600 degrees C. These compounds extend the previously known (RE)6M2+xX1-x (M = Co, Ni; X = Ga, In, Sn, Pb) series with the Ho6Co2Ga-type structure to X = Bi. The crystal structure of Ho12Co5Bi was refined by the Rietveld method from powder X-ray diffraction data obtained using synchrotron radiation (Pearson symbol oI36, orthorhombic, space group Immm, Z = 2, a = 9.37598(14) A, b = 9.37871(14) A, c = 9.85465(13) A). Unlike other Ho6Co2Ga-type compounds, the 2a site in Ho12Co5Bi is exclusively occupied by Co atoms. Four-probe electrical resistivity measurements on sintered polycrystalline samples of (RE)12Co5Bi indicated metallic behavior. Magnetic measurements revealed behavior ranging from frequency-dependent maxima in the ac susceptibility for Y12Co5Bi to possible ferrimagnetic ordering for Gd12Co5Bi to antiferromagnetic ordering with metamagnetic transitions for the remaining compounds. As confirmed by band structure calculations using Y12Co5Bi as a model compound, Y-Y and Y-Co interactions are the most important bonding components, but matrix effects are likely responsible for anomalously short Co-Co contacts in the structure.     

Simultaneous Voltammetric Determination of Zn,Cd and Pb at Bismuth Nanopowder Electrodes with Various Particle Size Distributions

Effect of particle size distribution on sensor characteristics of nano‐Bi fixed electrode has been investigated using square wave anodic stripping voltammetry. Bi nanopowders with various particle size distributions were synthesized by gas condensation (GC) method with the change of chamber pressure. As the chamber pressure decreased, the size of Bi nanopowder became smaller with narrower distribution due to a shorter residence time of Bi vapor. The square wave anodic stripping voltammograms (SWASV) showed well‐defined and highly reproducible peaks at ?1.2 V, ?0.8 V and ?0.6 V (vs. SCE), which are closely related to the oxidation of Zn, Cd and Pb, respectively. The sensitivity and detection limit of the nano‐Bi fixed electrode were quantitatively estimated from the analyses of SWASV. From the results, it is concluded that as the size of Bi nanopowder becomes smaller with narrower particle size distribution, the sensitivity and detection limit of sensor electrode for Zn, Cd and Pb are improved, which is ascribed to the increase in electrochemical‐active surface area.     

Slurry sampling flow injection chemical vapor generation inductively coupled plasma mass spectrometry for the determination of trace Ge,As, Cd,Sb, Hg and Bi in cosmetic lotions

A slurry sampling inductively coupled plasma mass spectrometry (ICP-MS) method has been developed for the determination of Ge, As, Cd, Sb, Hg and Bi in cosmetic lotions using flow injection (FI) vapor generation (VG) as the sample introduction system. A slurry containing 2% m/v lotion, 2% m/v thiourea, 0.05% m/v l-cysteine, 0.5 μg mL⁻¹ Co(II), 0.1% m/v Triton X-100 and 1.2% v/v HCl was injected into a VG-ICP-MS system for the determination of Ge, As, Cd, Sb, Hg and Bi without dissolution and mineralization. Because the sensitivities of the analytes in the slurry and that of aqueous solution were quite different, an isotope dilution method and a standard addition method were used for the determination. This method has been validated by the determination of Ge, As, Cd, Sb, Hg and Bi in GBW09305 Cosmetic (Cream) reference material. The method was also applied for the determination of Ge, As, Cd, Sb, Hg and Bi in three cosmetic lotion samples obtained locally. The analysis results of the reference material agreed with the certified value and/or ETV-ICP-MS results. The detection limit estimated from the standard addition curve was 0.025, 0.1, 0.2, 0.1, 0.15, and 0.03 ng  g⁻¹ for Ge, As, Cd, Sb, Hg and Bi, respectively, in original cosmetic lotion sample.     

Substitution effect on the photocatalytic degradation by the series AxBi26-xMo10O68+0.5y (A = Ba, y = 0; A = Bi, La, y = 2): a kinetic study

The compounds Ba2Bi24Mo10O68 and La2Bi24Mo10O69 were synthesized by the ceramic route and characterized by single crystal and powder X-ray diffraction, respectively. The structure of these phases is isostructural with that of Bi26Mo10O69. Along the b axis columns of [Bi12O14] units are separated by MoO4 tetrahedra and noncolumnar A (A = Ba, La) atoms. UV-visible spectra of Bi26Mo10O69, Ba2Bi24Mo10O68, and La2Bi24Mo10O69 suggest that band gap decreases on substitution of La and Ba for Bi at the noncolumnar site. The photocatalytic degradation of water pollutants such as phenol and substituted phenols was studied. All the catalysts show specificity toward nitro substituent at the para position in the aromatic ring.     

Synthesis, property characterization and photocatalytic activity of the novel composite polymer polyaniline/Bi2SnTiO7

A novel polyaniline/Bi(2)SnTiO(7 )composite polymer was synthesized by chemical oxidation in-situ polymerization method and sol-gel method for the first time. The structural properties of novel polyaniline/Bi(2)SnTiO(7) have been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray spectrometry. The lattice parameter of Bi(2)SnTiO(7) was found to be a = 10.52582(8) ?. The photocatalytic degradation of methylene blue was realized under visible light irradiation with the novel polyaniline/Bi(2)SnTiO(7) as catalyst. The results showed that novel polyaniline/Bi(2)SnTiO(7 )possessed higher catalytic activity compared with Bi(2)InTaO(7) or pure TiO(2) or N-doped TiO(2) for photocatalytic degradation of methylene blue under visible light irradiation. The photocatalytic degradation of methylene blue with the novel polyaniline/Bi(2)SnTiO(7) or N-doped TiO(2) as catalyst followed first-order reaction kinetics, and the first-order rate constant was 0.01504 or 0.00333 min(-1). After visible light irradiation for 220 minutes with novel polyaniline/Bi(2)SnTiO(7 )as catalyst, complete removal and mineralization of methylene blue was observed. The reduction of the total organic carbon, the formation of inorganic products, SO(4)2- and NO(3-), and the evolution of CO(2) revealed the continuous mineralization of methylene blue during the photocatalytic process. The possible photocatalytic degradation pathway of methylene blue was obtained under visible light irradiation.     

Synthesis, structure, and bonding of Eu3Bi(Sn,Bi)4. A rare inverse-Cr5B3-type structure with a new tin/bismuth network

The ternary phase Eu3Bi(Sn1-xBix)4 ( approximately 0 < x < approximately 0.15) has been synthesized by solid-state methods at high temperature. The crystal structure of the limiting Eu3Bi(Sn3.39Bi0.61(3)) has been determined by single-crystal X-ray analysis to be isopointal with an inverse-Cr5B3-type structure [space group I4/mcm, Z = 4, a = 8.826(1) A, c = 12.564(3) A, and V = 978.6(3) A3]. The structure contains slabs of three-bonded Sn/Bi atoms as puckered eight- and four-membered rings interlinked at all vertices, and these are separated by planar layers of individual Eu and Bi atoms. In the normal (stuffed) Cr5B3-type analogue Eu5Sn3Hx, these two units are replaced by a more highly puckered network of Eu cations around isolated Sn atoms and planar layers of isolated Eu atoms and Sn dimers, respectively. Band structures of limiting models of the phase calculated by TB-LMTO-ASA methods show a metallic character and indicate that the mixed Sn/Bi occupancy in the slabs in this structure for x > 0 probably originates with the electronic advantages of the pseudogap that would occur at the electron count of the ideal Zintl phase Eu3Bi(Sn3Bi). The stability of a competing phase reduces this limit to Eu3Bi(Sn3.4Bi0.6).     

Silver iodobismuthates: syntheses, structures, properties, and theoretical studies of [Bi2Ag2I10 2-]n and [Bi4Ag2I16 2-]n

Two novel silver iodobismuthates have been obtained: (Et4N)2n-[Bi2Ag2I10]n (1) with one-dimensional infinite chains built from bimetallic tetranuclear units and (Et4N)2n[Bi4Ag2I16]n (2) with a two-dimensional 44 grid assembly of the tetranuclear Bi4I16 subunits as nodes and Ag atoms as linkages. Their optical band gaps, 2.05 and 1.93 eV, fit nicely in a size correlation of the Bi/I subunit, which is further supported by the density functional theory studies.     

石墨炉原子吸收光谱法测定氯化钠、溴化钾和碘化钾中痕量铁铜铅铋

氯化钠、溴化钾、碘化钾在石墨炉原子吸收光谱法测定铁、铜、铅、铋时产生强的背景。提高灰化温度和时间能消除或降低此干扰。铅和铋的测定能用铂或钯作基体改进剂,但是铂的效果更好。     

Wismutmonojodid BiJ,eine Verbindung mit Bi(O) und Bi(II)

Bismuth Monoiodide, a Compound with Bi(O) and Bi(II) Bismuth monoiodide was synthesized in closed tubes from the elements as well as from Bi and HgI₂ as a black coloured crystalline compound. With increasing temperature BiI passes two transitions. α-BiI is stable below 370 K and changes to β-BiI by a martensitic transition. γ-BiI is the stable modification above 564 K and decomposes at 585 K peritectically to BiI₃ and a lower iodide. All three modification crystallize in the monoclinic space group C2/m. The structures (single crystal studies) of α-BiI and β-BiI are characterized by onedimensional infinite chains [Bi₄I₄] with covalent bonds but only weak interactions in between. The [Bi₄I₄]-chains are built up by two completely different Bi atoms. Bi(A) is only bonded to three Bi whereas Bi(B) has bonds to one Bi and four I. The average bond lengths are Bi? Bi = 304.5 pm and Bi? I = 313.7 pm respectively. The configuration of the Bi(A) atoms is typical for Bi^O and that one of the Bi(B) atoms is characteristic for Bi²⁺ with the electron configuration s²p¹. Therefore, α-BiI and β-BiI are mixed valence compounds [Bi^OBi²⁺I₄]. The structures are variants of the simple cubic polonium type of structure and differ in the stacking of connected units. The structures and their transitions, the possible configurations for monohalides BiX on principle as well as the energy balances of the disproportionation of Bi⁺ are discussed together in detail.     

Equilibrium, 1H and 13C NMR spectroscopy,and X-ray diffraction studies on the complexes Bi(DOTA)- and Bi(DO3A-Bu)

Several Bi(III) complexes are used in medicine as drugs. Bi(DO3A-Bu) has recently been proposed as a nonionic contrast agent in X-ray imaging (H(3)DO3A-Bu = 10-[2,3-dihydroxy-(1-hydroxymethyl)propyl]-1,4,7,10-tetraazacyclododecane-1,4,7,-triacetic acid). The solution equilibria and NMR structure and dynamics of Bi(DO3A-Bu) and of the similar Bi(DOTA)(-) have been investigated (H(4)DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid). The stability constants were determined with the study of the competition equilibria between Br(-) ions and the ligands DOTA or DO3A-Bu for the Bi(III) by spectrophotometry. The stability constants, obtained for Bi(DOTA)(-) and Bi(DO3A-Bu), are very high, log K = 30.3 and 26.8, respectively. Potentiometric titrations indicated the dissociation of one of the protons among the three alcoholic OH groups in Bi(DO3A-Bu). The dissociation constant is log K = 7.53 (0.09) indicating that at physiological pH about 50% of the species possess -1 charge. It was shown by (1)H and (13)C NMR spectroscopy that the OH group attached to the middle carbon atom of the "butriol" side chain is coordinated to the Bi(III) and starts to deprotonate at pH > 5.5. The crystal structure of NaBi(DOTA).H(2)O shows an octacoordinated arrangement of the donor atoms around the Bi(III), with no water in the inner sphere. The crystals belong to the centrosymmetric space group C2/c. The temperature dependent (1)H and (13)C NMR spectra indicate that both Bi(DOTA)(-) and Bi(DO3A-Bu)(-) complexes are fluxional. For Bi(DOTA), the Delta(deltadeltadeltadelta) right harpoon over left harpoon Lambda(lambdalambdalambdalambda) fluxionality was identified, and on the basis of the activation parameters, a synchronous motion was suggested for the fluxional motion resulting in the change of ring conformation and of the helicity of the complex. The transition state is supposed to be more symmetrical than the initial state. The deprotonated Bi(DO3A-Bu) has a highly asymmetric NMR structure in solution, and its fluxional motion is slower than that of Bi(DOTA)(-).     

Determination of Te,Bi, Ni,Sb and Au by X-ray fluorescence spectrometry following electroenrichment on a copper cathode

The electrodepositons of Te, Bi, Ni, Sb and Au from aqueous solution of pH = 1 on the cathode surface have been studied for X-ray fluorescence analysis (XRF). A special holder for a copper electrode has been constructed to perform the electrodeposition process on only one side of the electrode. After electrolysis, the copper electrode can be easily removed from the holder; after rinsing it with water and drying it can be analyzed by XRF. The proposed method of sample preparation and preconcentration of Te, Bi, Ni, Sb, Au provides suitable samples which are devoid of the negative and undesirable effects of XRF analysis, such as particle size and matrix effects. The influence of time on the deposition yield has been examined. The method of preconcentration is efficient. The inhomogeneity of the prepared specimens has been studied using internal standard method. The calibration is based on using synthetic standards, certified reference materials and standard addition method. The best results are achieved by the standard addition method. The agreement between results obtained with XRF analysis and certified values is satisfactory and indicates the usefulness of the proposed method for determination of Te, Bi, Ni, Sb and Au in anode slime.     

Synthesis, characterization and visible light photocatalytic properties of Bi2WO6/rectorite composites

Visible light-induced Bi(2)WO(6)/rectorite (BR) composites were prepared by a sol-gel method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectrum, Fourier transform infrared (FTIR) spectrum, X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmet-Teller (BET). The UV absorption edges of the BR-450 catalyst showed a marked red shift as compared to that of the pure Bi(2)WO(6). The photocatalytic activities of the as-prepared samples were evaluated by the photocatalytic degradation of 4BS dye in aqueous solution under visible light irradiation (>420 nm). The results showed that the BR-450 catalyst exhibited a strong adsorption capability and a higher photocatalytic degradation activity than the pure Bi(2)WO(6) for 4BS dye, which could be attributed to the synergetic effects of the adsorbability of rectorite and the photocatalytic property of Bi(2)WO(6) in it.     

Bismuth pyrostannate, Bi2Sn2O7, from the first structurally characterized heterobimetallic Bi:Sn alkoxides

The first heterobimetallic Bi:Sn alkoxide complexes [Bi(2)SnO(OCH(CF(3))(2))(5)(O(t)Bu)(3)(THF)] (1) and [BiSnO(OCH(CF(3))(2))(3)(O(t)Bu)(2)](2) (2) are described. The complexes were obtained through mixing and heating equimolar quantities of the component alkoxides, Bi(OCH(CF(3))(2))(3) and Sn(O(t)Bu)(4), under solvent-free conditions (1) and in THF (2). The solid-state structures were determined by single crystal X-ray diffraction showing ligand redistribution from Bi(III) to Sn(IV) in the two molecular species. Compound 2 behaves as a single-source precursor for the thermolytic formation of bismuth pyrostannate, Bi(2)Sn(2)O(7).     

Experimental and theoretical investigation on binary semiconductor clusters of Bi/Si, Bi/Ge, and Bi/Sn

Bi(m)M(n)- (M = Si, Ge, Sn) binary cluster anions are generated by using laser ablation on mixtures of Bi and M (M = Si, Ge, Sn) samples and studied by reflectron time-of-flight mass spectrometer (RTOF-MS) in the gas phase. Some magic number clusters are present in the mass spectra which indicate that they are in stable structures. For small anions (m + n < or = 6), their structures are investigated with the DFT method and the energetically lowest lying structures are obtained. For the binary anionic clusters with the same composition containing Si, Ge, and Sn, they share similar geometric and electronic structure in the small size except that BiSi3-, BiSi5-, Bi2Si2-, Bi2Si3-, and Bi4Sn2- are different for the lowest energetic structures, and the ground states for all the anions are in their lowest spin states. The calculated VDE (vertical detachment energy) and binding energy confirm the obviously magic number cluster of BiM4- (M = Si, Ge, Sn), which agrees with the experimental results.     

DFT calculations on the electronic structures of BiOX (X = F, Cl, Br, I) photocatalysts with and without semicore Bi 5d states

The electronic structures of BiOX (X = F, Cl, Br, I) photocatalysts have been calculated with and without Bi 5d states using the experimental lattice parameters, via the plane-wave pseudopotential method based on density functional theory (DFT). BiOF exhibits a direct band gap of 3.22 or 3.12 eV corresponding to the adoption of Bi 5d states or not. The indirect band gaps of BiOCl, BiOBr, and BiOI are 2.80, 2.36, and 1.75 eV, respectively, if calculated with Bi 5d states, whereas the absence of Bi 5d states reduces them to 2.59, 2.13, and 1.53 eV successively. The calculated gap characteristics and the falling trend of gap width with the increasing X atomic number agree with the experimental results, despite the common DFT underestimation of gap values. The shapes of valence-band tops and conduction-band bottoms are almost independent of the involvement of Bi 5d states. The indirect characteristic becomes more remarkable, and the conduction-band bottom flattens in the sequence of BiOCl, BiOBr, and BiOI. Both O 2p and X np (n = 2, 3, 4, and 5 for X = F, Cl, Br, and I, respectively) states dominate the valence bands, whereas Bi 6p states contribute the most to the conduction bands. With the growing X atomic number, the localized X np states shift closer toward the valence-band tops, and the valence and conduction bandwidths evolve in opposite trends. Atomic and bond populations have also been explored to elucidate the atomic interactions, along with the spatial distribution of orbital density.     

An investigation of secondary ion yield enhancement using Bi n 2+ (n=1, 3, 5) primary ions

We have investigated secondary ion yield enhancement using Bin2+ (n=1, 3, 5) primary ions impacting phenylalanine, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), cholesterol, Irganox 1010, and polymer films adsorbed on silicon and aluminum. Secondary ion yields are increased using Bi2+and Bi3(2+) primary ions for the molecular layers and polymers that can undergo allyl cation rearrangements. For Irganox 1010, the deprotonated molecular ion yields (m/z 1175; [M-H]-) are one to two times larger for Bi2+ and Bi(3)2+ primary ions than for Bi+ and Bi3+ at the same primary ion velocities. In the positive ion mode, the largest fragment ion yield (m/z 899) is 1.5 times larger for Bi2+ ions than for Bi+. For Bi3(2+) the largest fragment ion yield is only 70% of the ion yield using Bi3+, but the secondary ion yields of the fragment ions at m/z 57 and 219 are enhanced. For polymers that can undergo allyl cation rearrangement reactions the secondary ion yield enhancements of the monomer ions range from 1.3 to 4.3. For Bi(5)2+ primary ions, secondary ion yields were the same or slightly larger than for Bi5+ in the negative ion mass spectra for Irganox 1010, but lower in the positive ion mode. No secondary ion yield enhancements were measured on polymer samples for Bi5(2+). For all polymer films studied, secondary ion intensities from the oligomer regions are substantially decreased using Bin2+ (n=1, 3, 5). We discuss differences in the ionization mechanisms for doubly and singly-charged Bi primary ion bombardment.