Collision Cooling of Ions Stored in Quadrupole Radio-Frequency Trap

Moriwaki, Y.; Tachikawa, Masashi; Maeno, Yoshiharu; Shimizu, Tadao

doi:10.1143/jjap.31.l1640

Cited by 42 publications

(37 citation statements)

References 7 publications

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“…In such instances, although the kinetic energy associated with any individual collision is generally small, the cumulative effect of multiple collisions enables the collision-induced dissociation (CID) of a wide range of ions [16]. Consequently, many theoretical studies [17][18][19][20][21][22][23] and computer simulations [24 -29] of confined ion trajectories and the associated ion-neutral collision processes have accompanied analytical applications of RF multipoles.Rather than using relative kinetic energy and thermal energy in describing gaseous ion transport, it is often practical to consider two directly related quanti- ties, the ion effective temperature [30,31] and the buffer gas temperature, respectively. In the context of mass spectrometry, the effective temperature has often been viewed as the temperature characterizing a MaxwellBoltzmann energy distribution of ions that would produce a specified rate for a well-characterized, temperature-dependent ion process [32,33].…”

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Prediction of collective characteristics for ion ensembles in quadrupole ion traps without trajectory simulations

Goeringer

Viehland

Danailov

2006

J. Am. Soc. Mass Spectrom.

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Fundamental aspects are presented of a two-temperature moment theory for quadrupole ion traps developed via transformation of the Boltzmann equation. Solutions of the moment equations correspond to changes in the ensemble average for any function of ion velocity, because the Boltzmann equation reflects changes to an ion distribution as a whole. The function of primary interest in this paper is the ion effective temperature and its behavior during ion storage and resonance excitation. Calculations suggest that increases in ion effective temperature during resonance excitation are due primarily to power absorption from the main RF trapping field rather than from the dipolar excitation signal. The dipolar excitation signal apparently serves mainly to move ions into regions of the ion trap where the RF electric field, and thus ion RF heating, is greater than near the trap center. Both ideal and non-ideal ion trap configurations are accounted for in the moment equations by incorporating parameterized variables ã and q, which are modified versions of the commonly used forms for the DC and AC ring voltages, and b and d, which are new forms that account for the voltages applied to the endcaps. Besides extending the applicability of the moment equations to non-ideal quadrupole ion traps, the modified versions of the parameterized variables can have additional utility. T oday, a large number of analytical mass spectrometers depend exclusively upon electric fields for ion transport, manipulation, and mass analysis. The fields employed may be static (e.g., time-offlight) [1], dynamic (e.g., RF quadrupole [2][3][4][5]), or a combination of the two [6 -8]. Improvements in performance of RF devices have been realized by changes in the physical configuration and applied potentials [9 -12], which produce electric fields of increased complexity (e.g., hexapole, octapole, etc.). Furthermore, ion motion and physicochemical phenomena in such RF devices are influenced by the introduction of a buffer gas at substantial pressure. The high number of ionneutral collisions resulting from extended ion residence times and elevated buffer gas number density can prove beneficial for ion cooling and focusing [13,14]. In contrast, the average kinetic energy of the ions also can be increased significantly above the thermal energy of the neutrals via acceleration in an electric field. The most widely used approach for ion acceleration in electrodynamic ion traps, termed resonance excitation, uses a relatively low-amplitude AC signal at the fundamental frequency of ion axial oscillations applied to the endcaps [15]. An important application of that process in RF multipole devices is collisional activation (CA) [15], in which a portion of the ion-neutral relative (i.e., center-of-mass) kinetic energy is transferred into internal energy of the ions. In such instances, although the kinetic energy associated with any individual collision is generally small, the cumulative effect of multiple collisions enables the collision-induced dissociation (CID) o...

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Prediction of collective characteristics for ion ensembles in quadrupole ion traps without trajectory simulations

Goeringer

Viehland

Danailov

2006

J. Am. Soc. Mass Spectrom.

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“…The trap depth can be increased to 5.4 eV by setting V top = 15 V, at the cost of increased micromotion. As the stray field can rapidly reduce the trap depth, it required the use of the helium buffer gas to have sufficient signal and lifetimes to measure the field [91,92]. They used a helium pressure of 10 −5 Torr.…”

Section: Surface Ion Chipmentioning

confidence: 99%

Ion trapping for quantum information processing

2007

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In this paper we have reviewed the recent progresses on the ion trapping for quantum information processing and quantum computation. We have first discussed the basic principle of quantum information theory and then focused on ion trapping for quantum information processing. Many variations, especially the techniques of ion chips, have been investigated since the original ion trap quantum computation scheme was proposed. Full two-dimensional control of multiple ions on an ion chip is promising for the realization of scalable ion trap quantum computation and the implementation of quantum networks.

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“…͑19͒. 17 They approximated that rf heating represents an energy transfer per collision in the case of ion/neutral collisions in an rfq field. In order to apply this ion/neutral formula to the ion-ion collision case, they supposed that the charge density was a fitting parameter to reproduce ionion collision experiments, and the resulting is 100 times smaller than the calculated by Eq.…”

Section: E Rf Heating Ratementioning

confidence: 99%

Spectral shape of in situ mass spectra of sympathetically cooled molecular ions

Baba¹,

Waki²

2002

Journal of Applied Physics

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We formulated a model to reproduce the spectral shape of in situ mass spectra of sympathetically cooled molecular ions trapped in a linear radio-frequency-quadrupole. The molecular ions are sympathetically cooled by laser cooled ions. The mass spectrum is obtained by observing fluorescence emitted from the laser-cooled ions as we excite the resonant motion of the sympathetically cooled molecular ions in the trap. The model, which uses a pseudopotential and space-charge approach, reproduces the mass spectra of molecules. The model suggests that the variation of the space-charge density of the laser-cooled ions can produce in-trap kinetic excitation without the loss of the excited ions from the trap.

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Collision Cooling of Ions Stored in Quadrupole Radio-Frequency Trap

Cited by 42 publications

References 7 publications

Prediction of collective characteristics for ion ensembles in quadrupole ion traps without trajectory simulations

Prediction of collective characteristics for ion ensembles in quadrupole ion traps without trajectory simulations

Ion trapping for quantum information processing

Spectral shape of in situ mass spectra of sympathetically cooled molecular ions

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