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Featured Application: Aluminum nanoparticles are integrated with micron-scale particles to enhance hydrolytic sensitivity to water and accelerate hydrogen gas production. A method is described for activation of the reaction of room temperature water with micron-scale aluminum particles (μAl) by the addition of poly(epoxyhexane)-capped aluminum nanoparticles (Al NPs). By themselves, Al NPs react vigorously and completely with water at ambient temperatures to produce H2. While pure μAl particles are unreactive toward water, mixtures of the μAl particles comprising 10 to 90% (by mass) of Al NPs, demonstrated appreciable hydrolytic activation. This activation is attributed to the reaction of the Al NPs present with water to produce a basic solution. Speciation modelling, pH studies, and powder X-ray diffraction analysis of the hydrolysis product confirm that the pH change is the key driver for the activation of μAl rather than residual heat from the exothermicity of Al NP hydrolysis. A mechanism is proposed by which the nonreactive aluminum oxide layer of the μAl is eroded under basic conditions. Mixtures 10% by mass of Al NPs can be used to produce the optimal quantity of H2. [ABSTRACT FROM AUTHOR]

A new method of analysis employing the time-dependent response of long-period-grating (LPG) fiber-optic sensors is introduced. The current kinetic approach allows analysis of the time-dependent wavelength shift of the sensor, in contrast to previous studies, in which the LPG sensing element has been operated in an equilibrium mode and modeled with Langmuir adsorption behavior. A detailed kinetic model presented is based on diffusion of the analyte through the outer protective membrane coating into the affinity coating, which is bound to the fiber cladding. A simpler phenomenological approach presented is based on measurement of the slope of the time-dependent response of the LPG sensor. We demonstrate the principles of the kinetic methods by employing a commercial [Cu.sup.+2] sensor with a carboxymethylcellulose sensing element. The detailed mathematical model fits the time-dependent behavior well and provides a means of calibrating the concentration-dependent time response. In the current approach, copper concentrations below parts per [10.sup.6] are reliably analyzed. The kinetic model allows early-time measurement for low concentrations of the analyte, where equilibration times are long. This kinetic model should be generally applicable to other affinity-coated LPG fiber-optic sensors. OCIS codes: 060.2370, 000.1570.

Terminal dinuclear anion, Fe2(CO)4-, is formed on constant irradiation of gas phase Fe2(CO)7- at 1064 nanometers and undergoes electron detachment on further photoexcitation. The dinuclear anions are in the form of asymmetrical coordinated dimers and one of the metal atom behaves as a ligand. Terminal Cr2(CO)5- and Co2(CO)4- were also studied. Fourier transform ion cyclotron resonance mass spectrometer was used in the studies. Potential of the vibrationally-induced electron detachment theory for collision activation studies is discussed.

A synthesis of [7,10-mu-H-7-CO-7, 7-(PPh3) 2-isonido-7,8,9-Re[C.sub.2][B.sub.2][H.sub.9]] complex by treatment of the complex salt [NHMe3][3,3-Cl2-3,3-([CO.sub.2])-closo-3,1,2-Re[C.sub.2][B.sub.9][H.sub.11]] with PPh3 in refluxing tetrahydrofuran and isolated as intensely colored orange-red microcrystals is described. Spectroscopic NMR and IR data suggest that the product has a highly asymmetric structure with two inequivalent PPh3 ligands and a single CO ligand.

Laser desorption from ZnO and AgO produces small bare metal cluster ions. Laser desorption from a ZnO/AgO mixture produces an enhancement of the silver cluster ion signal with complete suppression of the zinc signal. The chemistry of Zn+2 indicates IP(Zn2)=9.0±0.2 eV and D0(Zn+–Zn)=0.56±0.2 eV. The reactivity of Zn+2 with alkenes and alcohols is characterized by displacement of a zinc atom and formation of Zn+–B (B=alcohol, alkene). The silver cluster ions are produced with excess kinetic energy; however, collisional cooling is achieved by trapping the cluster ions in a static pressure of argon. Charge transfer reactions indicate IP(Agn)<7.0 eV (n=3,5). Ag+3 and Ag+5 are unreactive with small alkanes, alkenes, and alcohols, but AgnL+2 (n=3,5; L=sec-butylamine) reacts with sec-butylamine via deamination and dehydrogenation indicating D0 (AgnL+2–butadiene) >1.73 eV. [ABSTRACT FROM AUTHOR]

We have adapted the techniques originally developed to measure ion kinetic energies in ion cyclotron resonance (ICR) spectrometry to study the single charge–transfer reaction of Nb2+ with benzene under thermal conditions in a Fourier transform ion cyclotron resonance mass spectrometer (FTICRMS). The partitioning of reaction exothermicity among the internal and translational modes available is consistent with a long-distance electron-transfer mechanism, in which the reactants approach on an ion-induced dipole attractive potential and cross to a repulsive potential at a critical separation of ∼7.5 Å when electron transfer occurs. The reaction exothermicity, 5.08 eV, is partitioned to translation of Nb+ , 0.81±0.25 eV, translation of C6 H6+, 1.22±0.25 eV, and internal excitation of C6 H6+ to produce the la2u electronic state, which is ∼3 eV above the ground state of the ion. We have also studied the kinetics of the reaction of Nb2+ with benzene and determined the rate constant, k = 1.4×10-9 cm3 molecule-1 s-1, and the efficiency, 0.60, of the process. These also support the proposed charge–transfer mechanism. In addition to the charge–transfer pathway, which accounts for 95% of the reaction products, Nb2+ is observed to dehydrogenate benzene to form Nb2+ (benzyne). This process implies D(Nb2+ –benzyne)≥79 kcal/mol. [ABSTRACT FROM AUTHOR]

The gas-phase reactions of Nb2+ with small alkanes at thermal energies are reported. For methane and ethane, dehydrogenation is a prominent reaction pathway. For propane and butane, charge transfer is virtually the only reaction pathway observed (>99%). NbCH2+2 and NbC2H2+2 formed in the reactions of Nb2+ with methane and ethane are thermodynamically stable with D(Nb2+–CH2)=197±10 kcal/mol, D(Nb+–CH+2)=107±10 kcal/mol, D(Nb2+–C2H2)≥74 kcal/mol, and D(Nb+–C2H+2)≥7 kcal/mol. The stability of these ions is most likely due to the charge-stabilizing effect of the metal center. Collision-induced dissociation of these ions results in charge-splitting reactions as well as reactions in which both charges remain on the metal center. Hydride transfer is observed to be competitive in the primary reactions of Nb2+ with alkanes. The hydride- and charge-transfer results are in qualitative agreement with a simple curve-crossing model. [ABSTRACT FROM AUTHOR]