			Home About us Contact

Trapped Ions (trapped + ion)

Distribution by Scientific Domains

Chemistry	60%

Selected Abstracts

Cavity QED with a trapped ion

FORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 2-3 2003
W. Vogel
A trapped ion in a leaky cavity is studied in the regime of strong atom-field coupling. Particular emphasis is paid on nonlinearities due to smooth localization of the ion's wavefunction and on decoherence effects caused by spontaneous emission and cavity losses. Possibilities of quantum-state preparation are analyzed and single-ion lasing is considered. [source]

Infrared multiple photon dissociation spectroscopy of ions in Penning traps

MASS SPECTROMETRY REVIEWS, Issue 3 2009
John R. Eyler
Abstract The ability of Paul and Penning traps to contain ions for time periods ranging from milliseconds to minutes allows the trapped ions to be subjected to laser irradiation for extended lengths of time. In this way, relatively low-powered tunable infrared lasers can be used to induce ion fragmentation when a sufficient number of infrared photons are absorbed, a process known as infrared multiple photon dissociation (IRMPD). If ion fragmentation is monitored as a function of laser wavelength, a photodissociation action spectrum can be obtained. The development of widely tunable infrared laser sources, in particular free electron lasers (FELs) and optical parametric oscillators/amplifiers (OPO/As), now allows spectra of trapped ions to be obtained for the entire "chemically relevant" infrared spectral region. This review describes experiments in which tunable infrared lasers have been used to irradiate ions in Penning traps. Early studies which utilized tunable carbon dioxide lasers with a limited output range are first reviewed. More recent studies with either FEL or OPO/A irradiation sources are then covered. The ionic systems examined have ranged from small hydrocarbons to multiply charged proteins, and they are discussed in approximate order of increasing complexity. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 28:448,467, 2009 [source]

A new linear ion trap mass spectrometer

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 6 2002
James W. Hager
Characteristics of mass selective axial ion ejection from a linear quadrupole ion trap in the presence of an auxiliary quadrupole field are described. Ion ejection is shown to occur through coupling of radial and axial motion in the exit fringing fields of the linear ion trap. The coupling is efficient and can result in extraction of as much as 20% of the trapped ions. This, together with the very high trapping efficiencies, can yield high sensitivity mass spectral responses. The experimental apparatus is based on the ion path of a triple quadrupole mass spectrometer allowing either the q2 collision cell or the final mass analysis quadrupole to be used as the linear trap. Space charge induced distortions of the mass resolved features while using the pressurized q2 linear ion trap occur at approximately the same ion density as reported for conventional three-dimensional ion traps. These distortions are, however, much reduced for the lower pressure linear trap possibly owing to the proposed axial ejection mechanism that leads to ion ejection only for ions of considerable radial amplitude. RF heating due to the high ejection q -value and the low collision frequency may also contribute. Two hybrid RF/DC quadrupole-linear ion trap instruments are described that provide high sensitivity product ion scanning while operated in the linear ion trap mode while also retaining all conventional triple quadrupole scan modes such as precursor ion and neutral loss scan modes. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Evaluation of axial DC offsets during scanning of a quadrupole ion trap for sensitivity improvements

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 9 2001
Timothy Vaden
In the normal operation of quadrupole ion trap mass spectrometers, approximately half of the trapped ions are ejected through the source endcap during a mass-selective instability scan. This reduces the sensitivity of the instrument by ,50%. In this preliminary study, a circuit was constructed that produced a dipolar DC offset on the axial modulation waveform to recover this lost ion current. A variable (0 to 10,V DC), positive and negative offset was applied to the source and detector endcap, respectively. This DC offset axially displaced the ion cloud toward the detector endcap increasing the probability of detection. Several compounds, including 11 pesticides, were evaluated. Sensitivity enhancements ranged from 13 to 97% (theoretical 100%). No spectral resolution problems were observed; however, a compound-dependent mass discrimination was observed in several cases. This mass discrimination problem is currently under investigation. Copyright © 2001 John Wiley & Sons, Ltd. [source]