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Mar 2000

Volume 71, Issue 3, pp. 1243-1570

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back to top CHARGED PARTICLE SOURCES, OPTICS and ACCELERATION

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

Ansgar Brock, Nestor Rodriguez, and Richard N. Zare

Rev. Sci. Instrum. 71, 1306 (2000); http://dx.doi.org/10.1063/1.1150456 (13 pages) | Cited 22 times

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A pseudorandom time-of-flight method (also called the cross-correlation method) 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. © 2000 American Institute of Physics.
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07.75.+h Mass spectrometers
41.85.-p Beam optics
07.05.Hd Data acquisition: hardware and software

A pump-probe photoionization mass spectrometer utilizing tunable extreme ultraviolet laser-produced-plasma radiation

R. Flesch, M. C. Schürmann, M. Hunnekuhl, H. Meiss, J. Plenge, and E. Rühl

Rev. Sci. Instrum. 71, 1319 (2000); http://dx.doi.org/10.1063/1.1150457 (6 pages) | Cited 9 times

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An experimental device is reported that utilizes time-correlated nanosecond light pulses in combination with photoionization mass spectrometry. A primary light pulse is generated by a tunable dye laser in the ultraviolet regime, which photolyzes neutral gas targets under collision free conditions. Subsequently, a time-correlated extreme ultraviolet-light pulse comes from a laser-produced plasma that is monochromatized in the 10–25 eV regime. The photolysis products are ionized by one-photon absorption, so that the cations are finally detected by time-of-flight mass spectrometry. The performance of this experimental approach is characterized by investigating the primary photolysis products of chlorine dioxide. Finally, possible applications of this approach are briefly discussed. © 2000 American Institute of Physics.
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07.75.+h Mass spectrometers
07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment
07.60.-j Optical instruments and equipment
82.50.Bc Processes caused by infrared radiation
82.50.Hp Processes caused by visible and UV light
42.55.Vc X- and γ-ray lasers

Pulsed field ionization-photoion spectroscopy using two-bunch synchrotron radiation: Time-of-flight selection scheme

G. K. Jarvis, R. C. Shiell, J. W. Hepburn, Y. Song, and C. Y. Ng

Rev. Sci. Instrum. 71, 1325 (2000); http://dx.doi.org/10.1063/1.1150458 (7 pages) | Cited 8 times

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We have demonstrated that the time-of-flight (TOF) selection method for pulsed field ionization (PFI) photoelectron detection [Jarvis et al., Rev. Sci. Instrum. 70, 2615 (1999)] can also be applied for the detection of PFI-photoions (PFI-PIs) using the two-bunch synchrotron radiation at the Advanced Light Source. By employing the supersonic beam technique to lower the translational temperature of the sample gas, we show that background prompt ions formed in direct and spontaneous autoionization processes arrive at the ion detector in a pattern similar to that of the vacuum ultraviolet light bunches. The PFI-PIs formed at dark gaps can be designed to arrive at the detector in between adjacent prompt ion peaks, enabling the gating of the PFI-PI signal with only minor contamination from background prompt ions. This experiment has revealed important considerations for the design of a general TOF selection scheme for PFI-PI detection using synchrotron radiation. © 2000 American Institute of Physics.
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07.81.+a Electron and ion spectrometers
07.75.+h Mass spectrometers
07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment
07.60.-j Optical instruments and equipment

Development of a high precision quadrupole mass filter using the zero-method control circuit

O. Tsukakoshi, T. Hayashi, K. Yamamuro, and M. Nakamura

Rev. Sci. Instrum. 71, 1332 (2000); http://dx.doi.org/10.1063/1.1150459 (5 pages)

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A high precision quadrupole mass filter has been developed using the zero-method control circuit. With this method, peak values of a control voltage are compared with a high-precision reference voltage and detected by a diode and signal-producing resistance connected in series. The dc component of the signal is selectively amplified and fed back to a module in the amplifying system of the rf voltage so as to minimize the voltage in excess of the reference voltage. An instrument has been constructed and the doublet of 4He+–D2+ has been successfully separated. © 2000 American Institute of Physics.
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07.75.+h Mass spectrometers
84.30.Jc Power electronics; power supply circuits

Velocity imaging photoionization coincidence apparatus for the study of angular correlations between electrons and fragment ions

M. Takahashi, J. P. Cave, and J. H. D. Eland

Rev. Sci. Instrum. 71, 1337 (2000); http://dx.doi.org/10.1063/1.1150460 (8 pages) | Cited 50 times

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A new apparatus has been developed to detect and measure angular correlations between energy-selected photoelectrons and coincident mass-analyzed fragment ions from photoionization at selected wavelengths. It achieves velocity imaging for electrons and ions simultaneously and has high collection efficiency for both particles, with moderate mass and energy resolution. Angular and energy correlations between the two particles are measured, as are the angular distributions of each particle independently relative to the light polarization direction. Fixed-molecule electron angular distributions are deduced in cases of pure axial recoil. Examples of angular distributions from photoionization of diatomic molecules are reported. © 2000 American Institute of Physics.
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07.81.+a Electron and ion spectrometers
07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment
07.60.-j Optical instruments and equipment
07.75.+h Mass spectrometers

Measurement of mechanical vibrations excited in aluminum resonators by 0.6 GeV electrons

G. D. van Albada, E. Coccia, V. Fafone, H. van der Graaf, G. Heijboer, J. W. van Holten, W. J. Kasdorp, J. B. van der Laan, L. Lapikás, G. Mazzitelli, G. J. L. Nooren, C. W. J. Noteboom, J. E. J. Oberski, G. Pallottino, H. Z. Peek, et al.

Rev. Sci. Instrum. 71, 1345 (2000); http://dx.doi.org/10.1063/1.1150461 (10 pages) | Cited 6 times

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We present measurements of mechanical vibrations induced by 0.6 GeV electrons impinging on cylindrical and spherical aluminum resonators. To monitor the amplitude of the resonator’s vibrational modes we used piezoelectric ceramic sensors calibrated by standard accelerometers. Calculations using the thermo-acoustic conversion model agree well with the experimental data, as demonstrated by specific variations of the excitation strengths with the absorbed energy, and with the traversing particles’ track positions. For the first longitudinal mode of the cylindrical resonator we measured a conversion factor of 7.4±1.4 nm/J, confirming the model value of 10 nm/J. Also, for the spherical resonator, we found the model values for the L = 2 and L = 1 mode amplitudes to be consistent with our measurement. We thus have confirmed the applicability of the model, and we note that calculations based on the model have shown that next generation resonant mass gravitational wave detectors can only be expected to reach their intended ultrahigh sensitivity if they are shielded by an appreciable amount of rock, where a veto detector can reduce the background of remaining impinging cosmic rays effectively. © 2000 American Institute of Physics.
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04.80.Nn Gravitational wave detectors and experiments
95.55.Ym Gravitational radiation detectors; mass spectrometers; and other instrumentation and techniques
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
85.50.-n Dielectric, ferroelectric, and piezoelectric devices
06.20.F- Units and standards

Absolute calibration of a multichannel plate detector for low energy O, O−, and O+

T. M. Stephen and B. L. Peko

Rev. Sci. Instrum. 71, 1355 (2000); http://dx.doi.org/10.1063/1.1150462 (5 pages) | Cited 19 times

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Absolute detection efficiencies of a commercial multichannel plate detector have been measured for O, O+, and O−, impacting at normal incidence for energies ranging from 30–1000 eV. In addition, the detection efficiencies for O relative to its ions are presented, as they may have a more universal application. The absolute detection efficiencies are strongly energy dependent and significant differences are observed for the various charge states at lower energies. The detection efficiencies for the different charge states appear to converge at higher energies. The strongest energy dependence is for O+; the detection efficiency varies by three orders of magnitude across the energy range studied. The weakest dependence is for O−, which varies less than one order of magnitude. © 2000 American Institute of Physics.
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07.75.+h Mass spectrometers
06.20.F- Units and standards
29.40.Gx Tracking and position-sensitive detectors
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