Synthesis of organo-uranium(II) species in the gas-phase using reactions between [UH] and nitriles.

One challenge in the quest to map the intrinsic reactivity of model actinide species has been the controlled synthesis of organo-actinide ions in the gas phase. We report here evidence that a series of gas-phase, σ-bonded [U-R] species (where R = CH, CH, CH, CH, or CH) can be generated for subsequent study of ion-molecule chemistry by using preparative tandem mass spectrometry (PTMS) ion-molecule reactions between [UH] and a series of nitriles. Density functional theory calculations support the hypothesis that the [U-R] ions are created in a pathway that involves intramolecular hydride attack and the elimination of neutral HCN.

Reactions of gas-phase uranyl formate/acetate anions: reduction of carboxylate ligands to aldehydes by intra-complex hydride attack.

In a previous study, electrospray ionization, collision-induced dissociation (CID), and gas-phase ion-molecule reactions were used to create and characterize ions derived from homogeneous precursors composed of a uranyl cation (UO) coordinated by either formate or acetate ligands [E. Perez, C. Hanley, S.

Gas-phase synthesis of [OU-X] (X = Cl, Br and I) from a UO precursor using ion-molecule reactions and an [OUCH] intermediate.

Difficulty in the preparation of gas-phase ions that include U in middle oxidation states(III,IV) have hampered efforts to investigate intrinsic structure, bonding and reactivity of model species. Our group has used preparative tandem mass spectrometry (PTMS) to synthesize a gas-phase U-methylidyne species, [OUCH], by elimination of CO from [UO(CCH)] [M. J.

Conversion of a UO Precursor to UH and U Using Tandem Mass Spectrometry to Remove Both "yl" Oxo Ligands.

Multiple-stage collision-induced dissociation (CID) of a uranyl propiolate cation, [UO(OC-C≡CH)], can be used to prepare the U-methylidyne species [O═U≡CH] [ , , 796-805]. Here, we report that CID of [O═U≡CH] causes elimination of CO to create [UH], followed by a loss of H to generate U. A feasible, multiple-step pathway for the generation of [UH] was identified using DFT calculations.

Intrinsic reactivity of [OUCH] : Apparent synthesis of [OUS] by reaction with CS.

Rationale: Building on our report that collision-induced dissociation (CID) can be used to create the highly reactive U-alkylidyne species [O=U≡CH] , our goal was to determine whether the species could be as an intermediate for synthesis of [OUS] by reaction with carbon disulfide (CS ).

Methods: Cationic uranyl-propiolate precursor ions were generated by electrospray ionization, and multiple-stage CID in a linear trap instrument was used to prepare [O=U≡CH] . Neutral CS was admitted into the trap through a modified He inlet and precision leak valves.

Intrinsic chemistry of [OUCH]: reactions with HO, CHC[triple bond, length as m-dash]N and O.

We report the first experimental study of the intrinsic chemistry of a U-methylidyne species, focusing on reaction of [OUCH]+ with H2O, O2 and CH3C[triple bond, length as m-dash]N in the gas phase. DFT was also used to determine reaction pathways, and establish the mechanism by which [OUCH]+ is formed through collision-induced dissociation of [UO2(C[triple bond, length as m-dash]CH)]+.

Two-dimensional optical quasicrystal potentials for ultracold atom experiments.

Quasicrystals are nonperiodic structures having no translational symmetry but nonetheless possessing long-range order. The material properties of quasicrystals, particularly their low-temperature behavior, defy easy description. We present a compact optical setup for creating quasicrystal optical potentials with five-fold symmetry using interference of nearly co-propagating beams for use in ultracold atom quantum simulation experiments.

Isotope labeling and infrared multiple-photon photodissociation investigation of product ions generated by dissociation of [ZnNO(CHOH)]: Conversion of methanol to formaldehyde.

Electrospray ionization was used to generate species such as [ZnNO(CHOH)] from Zn(NO)•XHO dissolved in a mixture of CHOH and HO. Collision-induced dissociation of [ZnNO(CHOH)] causes elimination of CHOH to form [ZnNO(CHOH)]. Subsequent collision-induced dissociation of [ZnNO(CHOH)] causes elimination of 47 mass units (u), consistent with ejection of HNO.

Collision-induced dissociation of uranyl-methoxide and uranyl-ethoxide cations: Formation of UO2 H(+) and uranyl-alkyl product ions.

Rationale: The lower levels of adventitious H2 O in a linear ion trap allow the fragmentation reactions of [UO2 OCH3 ](+) and [UO2 OCH2 CH3 ](+) to be examined in detail.

Methods: Methanol- and ethanol-coordinated UO2 (2+) -alkoxide precursors were generated by electrospray ionization (ESI). Multiple-stage tandem mass spectrometry (MS(n) ) and collision-induced dissociation (CID) were performed using a linear ion trap mass spectrometer.

Coherent Addressing of Individual Neutral Atoms in a 3D Optical Lattice.

We demonstrate arbitrary coherent addressing of individual neutral atoms in a 5×5×5 array formed by an optical lattice. Addressing is accomplished using rapidly reconfigurable crossed laser beams to selectively ac Stark shift target atoms, so that only target atoms are resonant with state-changing microwaves. The effect of these targeted single qubit gates on the quantum information stored in nontargeted atoms is smaller than 3×10^{-3} in state fidelity.

3D projection sideband cooling.

We demonstrate 3D microwave projection sideband cooling of trapped, neutral atoms. The technique employs state-dependent potentials that enable microwave photons to drive vibration-number reducing transitions. The particular cooling sequence we employ uses minimal spontaneous emission, and works even for relatively weakly bound atoms.