Consecutive photodissociation of a single complex molecular ion

Højbjerre, Klaus; Offenberg, D.; Bisgaard, Christer Z.; Stapelfeldt, Henrik; Staanum, Peter; Mortensen, Anders; Drewsen, Michael

doi:10.1103/physreva.77.030702

Cited by 43 publications

(35 citation statements)

References 26 publications

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“…6,29 Drewsen and co-workers 30 circumvented this problem by using just a single nonfluorescing ion, which is sympathetically cooled by a single laser-cooled ion, allowing a relative mass resolution of m / ⌬m Ϸ 10 4 . 18,28,31 With optimizations, the technique is expected to be able to achieve a resolution of m / ⌬m Ϸ 10 5 -10 6 . 30 For the harmonic potential at the center of the linear Paul trap, it can be shown that the two eigenfrequencies for the low-amplitude axial motion of two equally charged ions are given by 28,32…”

Section: Single-ion Mass Spectrometrymentioning

confidence: 99%

Cold chemistry with electronically excited Ca+ Coulomb crystals

Gingell

Bell

Oldham

et al. 2010

The Journal of Chemical Physics

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Rate constants for chemical reactions of laser-cooled Ca(+) ions and neutral polar molecules (CH(3)F, CH(2)F(2), or CH(3)Cl) have been measured at low collision energies (/k(B)=5-243 K). Low kinetic energy ensembles of (40)Ca(+) ions are prepared through Doppler laser cooling to form "Coulomb crystals" in which the ions form a latticelike arrangement in the trapping potential. The trapped ions react with translationally cold beams of polar molecules produced by a quadrupole guide velocity selector or with room-temperature gas admitted into the vacuum chamber. Imaging of the Ca(+) ion fluorescence allows the progress of the reaction to be monitored. Product ions are sympathetically cooled into the crystal structure and are unambiguously identified through resonance-excitation mass spectrometry using just two trapped ions. Variations of the laser-cooling parameters are shown to result in different steady-state populations of the electronic states of (40)Ca(+) involved in the laser-cooling cycle, and these are modeled by solving the optical Bloch equations for the eight-level system. Systematic variation of the steady-state populations over a series of reaction experiments allows the extraction of bimolecular rate constants for reactions of the ground state ((2)S(1/2)) and the combined excited states ((2)D(3/2) and (2)P(1/2)) of (40)Ca(+). These results are analyzed in the context of capture theories and ab initio electronic structure calculations of the reaction profiles. In each case, suppression of the ground state rate constant is explained by the presence of a submerged or real barrier on the ground state potential surface. Rate constants for the excited states are generally found to be in line with capture theories.

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Section: Single-ion Mass Spectrometrymentioning

confidence: 99%

Cold chemistry with electronically excited Ca+ Coulomb crystals

Gingell

Bell

Oldham

et al. 2010

The Journal of Chemical Physics

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“…14. Sympathetic cooling of 20 M + ions by 60 40 Ca + , 24 Mg + , or 9 Be + cooled ions, respectively. The graphs show temperatures of (a) coolant ions and (b) sympathetically cooled ions versus the mass number of sympathetically cooled ions.…”

Section: MD Simulation Of Sympathetic Coolingmentioning

confidence: 99%

“…Translationally cold molecular samples are easily produced by sympathetic cooling and photochemical reactions. Photodissociation processes can be studied in detail with single-ion spectroscopy [8,9]. Recently, rovibrational spectroscopy of sympathetically cooled HD + ions in Coulomb crystals has been demonstrated at very low temperatures, when combining Coulomb crystals with a resonance-enhanced multiphoton dissociation technique [10].…”

Section: Introductionmentioning

confidence: 99%

Characterization of ion Coulomb crystals in a linear Paul trap

Okada¹,

Wada²,

Takayanagi³

et al. 2010

Phys. Rev. A

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We describe a simple and fast method for simulating observed images of ion Coulomb crystals. In doing so, cold elastic collisions between Coulomb crystals and virtual very light atoms are implemented in a molecular dynamics (MD) simulation code. Such an approach reproduces the observed images of Coulomb crystals by obtaining density plots of the statistics of existence of each ion. The simple method has the advantage of short computing time in comparison with previous calculation methods. As a demonstration of the simulation, the formation of a planar Coulomb crystal with a small number of ions has been investigated in detail in a linear ion trap both experimentally and by simulation. However, also large Coulomb crystals including up to 1400 ions have been photographed and simulated to extract the secular temperature and the number of ions. For mediumsized crystals, a comparison between experiments and calculations has been performed. Moreover, an MD simulation of the sympathetic cooling of small molecular ions was performed in order to test the possibility of extracting the temperature and the number of refrigerated molecular ions from crystal images of laser-cooled ions. Such information is basic to studying ultracold ion-molecule reactions using ion Coulomb crystals including sympathetically cooled molecular ions.

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“…11,12 With the long ion storage times that are reached in them in combination with laser cooling, 13,14 they are ideal tools for research with small particle numbers at very low translational temperatures. [15][16][17][18][19][20] High-resolution laser spectroscopy benefits from these advantages, and thus currently the most accurate optical frequency measurements and comparisons are based on such traps. 12,21 By applying sympathetic cooling [22][23][24][25] via a co-trapped cooling ion, and with the recent introduction of quantum logic based detection schemes, 26,27 it has become possible to detect the internal state of the spectroscopy ion after probing without resorting to a fast cycling transition in the spectroscopy ion.…”

Section: Introductionmentioning

confidence: 99%

Cryogenic linear Paul trap for cold highly charged ion experiments

Schwarz

Versolato

Windberger

et al. 2012

Review of Scientific Instruments

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Storage and cooling of highly charged ions require ultra-high vacuum levels obtainable by means of cryogenic methods. We have developed a linear Paul trap operating at 4 K capable of very long ion storage times of about 30 h. A conservative upper bound of the H(2) partial pressure of about 10(-15) mbar (at 4 K) is obtained from this. External ion injection is possible and optimized optical access for lasers is provided, while exposure to black body radiation is minimized. First results of its operation with atomic and molecular ions are presented. An all-solid state laser system at 313 nm has been set up to provide cold Be(+) ions for sympathetic cooling of highly charged ions.

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Consecutive photodissociation of a single complex molecular ion

Cited by 43 publications

References 26 publications

Cold chemistry with electronically excited Ca+ Coulomb crystals

Cold chemistry with electronically excited Ca+ Coulomb crystals

Characterization of ion Coulomb crystals in a linear Paul trap

Cryogenic linear Paul trap for cold highly charged ion experiments

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