Pseudorandom time-of-flight analysis with a time-of-flight mass spectrometer

Bewig, L.; Buck, U.; Gandhi, Suketu R.; Winter, M.

doi:10.1063/1.1146606

Cited by 15 publications

(23 citation statements)

References 23 publications

(17 reference statements)

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“…The scattered products were resolved and detected by a time-offlight mass spectrometer (TOF-MS) applying pulsed UV-laser photoionization. 17 mass spectrometer equipped with an electron bombardment ionizer was used for the mass and velocity analysis of the direct H 2 O cluster beam. Both detectors can be rotated in the plane defined by the sodium and water beams, enabling us to measure the product angular distributions in an angular range from -3°t o 92°with respect to the Na cluster beam.…”

Section: Methodsmentioning

confidence: 99%

Reactions of Sodium Clusters with Water Clusters

Bewig¹,

Buck²,

Rakowsky³

et al. 1998

J. Phys. Chem. A

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In a crossed molecular beam experiment, the reactive scattering of sodium clusters Na n (n E 21) with water clusters (H 2 O) m (m E 40) is investigated. By measuring the angular and the velocity distributions of the scattered reaction products, direct information on the reaction mechanisms is obtained. The sodium clusters are generated in a supersonic expansion of sodium vapor from an oven with a refilling system with argon carrier gas. The products are detected by photoionization at wavelengths of 308 and 355 nm and mass analyzed in a time-of-flight mass spectrometer (TOF-MS). In addition, a fast chopper with a pseudorandom sequence modulating the sodium cluster beam allows us to determine at the same time the velocity distributions of the products. The scattering of Na clusters with H 2 O clusters shows only one series of reaction products, that is, solvated sodium atoms Na(H 2 O) m (m E 32) with maximum intensities at m ) 4, 5, 6. For all products, the measured angular and velocity distributions exhibit the formation of a complex that is stabilized by isotropic evaporation of water molecules. The detected products have low translational energy. Products containing NaOH have not been observed.

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Section: Methodsmentioning

confidence: 99%

Reactions of Sodium Clusters with Water Clusters

Bewig¹,

Buck²,

Rakowsky³

et al. 1998

J. Phys. Chem. A

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“…Shifting of the sequence shown in Fig. 1͑c͒ by 3 1 2 elements to the right as indicated by the arrow and keeping in mind that the sequence is cyclic, meaning it flips around at the end, produces the sequence in Fig. 1͑b͒, vide infra.…”

Section: B Operational Modesmentioning

confidence: 99%

“…Time-of-flight ͑TOF͒ analysis has found widespread application because particle velocity, energy or momentum, and mass can be determined from such an experiment by constraining the appropriate parameters for the experiment. Examples of the application of the technique are found in neutron and molecular beam scattering of neutral particles, [1][2][3] where it is the method of choice for extracting the desired velocity information. This method has also be applied to charged particles, and examples are photoelectron spectroscopy 4 and time-of-flight mass spectrometry ͑TOFMS͒.…”

Section: Introductionmentioning

confidence: 99%

“…There the solution is known under the name of pseudorandom or crosscorrelation time-of-flight analysis and allows for duty cycles of 50%. [1][2][3] In the following we describe the implementation of this method in TOFMS. The name Hadamard transform time-of-flight mass spectrometry ͑HT-TOFMS͒ was chosen for this implementation for several reasons.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of a Hadamard transform time-of-flight mass spectrometer

Brock

Rodríguez

Zare

2000

Review of Scientific Instruments

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A pseudorandom time-of-flight method ͑also called the cross-correlation method͒ has been used to perform time-of-flight mass spectrometry with a duty cycle of 50%. Modulation of an ion beam is accomplished by deflecting the ion beam with an interleaved comb of oppositely charged elements. Maximum-length pseudorandom sequences based on Hadamard-type difference sets are produced by feedback shift register circuitry and used for ion beam modulation. The inverse transformation of the recorded signal is carried out speedily with the help of the fast Hadamard transform, which allows real-time monitoring of the mass spectrum. The components of the instrument are described, and its performance is characterized. Trajectory simulations are found to be in good agreement with experimental findings, which aids in understanding the modulation dynamics. It is found that the wire comb modulator can be modeled as a set of ideal deflection plates of length 0.875 l, where l is the spacing between oppositely charged wires.

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“…A new technique called delay-series correlation 18 employs correlation calculations to accurately detect and pinpoint peptide modifications, thus facilitating the interpretation of isotopically labelled peptide spectra. Finally, correlation analysis has been utilized in the development of new instrumentation, specifically Hadamard transform (HT) TOFMS (also called cross-correlation TOFMS) 19,20 and Hadamard transform ion mobility spectrometry (HT-IMS). 21 Based on the principles of correlation, HT-TOFMS instrumentation offers an improved duty cycle (up to 50%) compared with 20% obtained with traditional orthogonal TOFMS and similar duty-cycle capabilities have been reported with HT-IMS systems.…”

Section: Introductionmentioning

confidence: 99%