Abstract
The internal energy distributions, P(ɛ), of a millisecond pulsed radio frequency glow discharge plasma were investigated using tungsten hexcarbonyl W(CO)6 as a “thermometer molecule”. Vapor of the probe molecule, W(CO)6, was introduced into the plasma and subjected to various ionization and excitation processes therein. The resultant molecular and fragment ions were monitored using a Time-of-Flight mass spectrometer. Ion abundance data were utilized in combination with the known energetics of W(CO)6 to construct the P(ɛ) plots. The P(ɛ) of W(CO)6 exhibited strong temporal dependence over the pulse cycle: Distinct internal energy distributions were found at the discharge breakdown period (prepeak), the steady state period (plateau), and the post-pulse period (afterpeak). Spatial variation in P(ɛ) was also observed, especially during the plateau regime. The observations suggest that this pulsed glow discharge affords excellent energy tunability that can be used to perform selective ionization and fragmentation for molecular, structural, and elemental information. Parametric studies were performed to evaluate the effects of discharge pressure and operating power on P(ɛ). These studies also provided insight into the correlation of the observed P(ɛ)s with the fundamental ionization and excitation mechanisms in the plasma. The temporal and spatial variations in P(ɛ) were hence attributed to changes in the dominant energy transfer processes at specific times in specific regions of the plasma. These data will be useful in future efforts to optimize the analytical performance of this source for chemical speciation.
Similar content being viewed by others
References
Majidi, V.; Moser, M.; Lewis, C.; Hang, W.; King, F. L. Explicit Chemical Seperation by Microsecond Glow Discharge Time-of-Flight Mass Spectrometry: Concurrent Acquisition of Structural, Molecular, and Elemental Information. J. Anal. At. Spectrom. 2000, 15, 19–25.
Marcus, R. K.; Evans, E. H.; Caruso, J. A. Tunable Plasma Sources in Analytical Spectroscopy. Current Status and Projections. J. Anal. At. Spectrom. 2000, 15, 1–5.
Houk, R. S.; Thompson, Joseph J. Inductively Coupled Plasma Mass Spectrometry. Mass Spectrom. Rev. 1988, 7, 425–461.
Levsen, K. Fundamental Aspects of Organic Mass Spectrometry; Verlag Chemie: New York, 1978, Chap II.
Faubert, D.; Giroux, G. J. C.; Bertrand, M. J. Selective Fragmentation and Ionization of Organic Compounds Using an Energy-Tunable Rare-Gas Metastable Source. Int. J. Mass Spectrom. Ion Processes 1993, 124, 69–77.
O’Connor, G.; Ebdon, L.; Evans, E. H. Low Pressure Inductively Coupled Plasma Ion Source for Molecular and Atomic Mass Spectrometry: The Effect of Reagent Gases. J. Anal. At. Spectrom. 1997, 12, 1263–1269.
Chapman, B. N. Glow Discharge Processes; John Wiley and Sons: New York, 1980.
Klingler, J. A.; Barshick, C. M.; Harrison, W. W. Factors Influencing Ion Signal Profiles in Pulsed Glow Discharge Mass Spectrometry. Anal. Chem. 1991, 63, 2571–2576.
Harrison, W. W.; Yang, C.; Oxley, Eric Pulsed Glow Discharge: Temporal Resolution in Analytical Spectroscopy. Anal. Chem. 2001, 73, 480A-487A.
Steiner, R. E.; Lewis, C. L.; King, F. L. Time-of-Flight Mass Spectrometry with a Pulsed Glow Discharge Ionization Source. Anal. Chem. 1997, 69, 1715–1721.
Jackson, G. P.; Lewis, C. L.; Doorn, S. K.; Majidi, V.; King, F. L. Spectral, Spatial, and Temporal Characteristics of a Milliosecond Glow Discharge: Metastable Argon Atom Production. Spectrochim. Acta 2001, 56B, 2449–2464.
Lewis, C. L.; Jackson, G. P.; Doorn, S. K.; Majidi, V.; King, F. L. Spectral, Spatial, and Temporal Characterization of a Millisecond Pulsed Glow Discharge: Analyte Emission and Ionization. Spectrochim. Acta 2001, 56B, 487–501.
Lewis, C. L.; Qxley, E. S.; Pan, C.; King, F. L. Determination of Ca+ in the Presence of Ar+: An illustration of the Utility of Time-Gated Detection in Pulsed Glow Dischage Mass Spectrometry. Anal. Chem. 1999, 71, 230–234.
Steiner, R. E.; Lewis, C. L.; Majidi, V. Consideration of a Millisecond Pulsed Glow Discharge Time-of-Flight Mass Spectrometer for Concurrent Elemental and Molecular Analysis. J. Anal. At. Spectrom. 1999, 14, 1537–1541.
Lewis, C. L.; Moser, M. A.; Dale, D. E., Jr.; Hang, W.; Hassell, C.; King, F. L.; Majidi, V. Time-Gated Pulsed Glow Discharge: Real-Time Chemical Speciation at the Elemental, Structural, and Molecular Level for Gas Chromatography Time-of-Flight Mass Spectrometry. Anal. Chem. 2003, 75, 1983–1996.
Wysocki, V. H.; Kenttamaa, H. I.; Cooks, R. Graham Internal Energy Distributions of Isolated Ions after Activation by Various Methods. Int. J. Mass Spectrom. Ion Processes 1987, 75, 181–208.
Kenttamaa, H. I.; Cooks, R. Graham Internal Energy Distributions Acquired Through Collisional Activation at Low and High Energies. Int. J. Mass Spectrom. Ion Processes 1985, 64, 79–83.
Hayakawa, S.; Harada, K. Study of Dissociation of Neutral Intermediates Using Charge Inversion Mass Spectrometry. J. Chem. Phys. 2000, 112, 8432–8435.
Turner, D. W.; Baker, C.; Baker, A. D.; Brundle, C. R. Molecular Photoelectron Spectroscopy; Interscience: New York, 1969, Chap III.
Horning, S. R.; Kotiaho, T.; Cooks, R. Graham Dissociative Charge Transfer of Singly- and Doubly-Charged Rare Gas Ions with W(CO)6. Int. J. Mass Spectrom. Ion Processes 1991, 110, 1–29.
Smith, R. L.; Serxner, D.; Hess, K. R. Assessment of Relative Role of Penning Ionization in Low-Pressure Glow Discharge. Anal. Chem. 1989, 61, 1103–1108.
Jager, R.; Becker, J. S.; Dietze, H.-J.; Boekaert, J. A. C. Investigation on the Ions Energy Distribution in an Analytical Radiofrequency Glow Discharge and its Mass Spectrometric Application. Int. J. Mass Spectrom. Ion Processes 1997, 171, 183–189.
Olthoff, J. K.; Brunt, R. J. Van Radovanov, S. B. Ion Kinetic-Energy Distribution in Argon rf Glow Discharge. J. Appl. Phys. 1992, 72, 4566–4574.
Busch, K. L.; Glish, G. L.; McLuckey, S. A. Mass Spectrometry/Mass Spectrometry: Techniques and Applications of Tandem Mass Spectromerty; VCH Publishers: New York, 1988, Chap III.
McLuckey, S. A.; Glish, G. L.; Asano, K. G.; Grant, B. C. Atmospheric Sampling Glow Discharge Ionization Source for the Determination of Trace Organic Compounds in Ambient Air. Anal. Chem. 1988, 60, 2220–2227.
Biondi, M. A. Diffusion, De-excitation, and Ionization Cross Sections for Metastable Atoms. I. Phys. Rev. 1952, 88, 660.
King, F. L.; Pan, C. Temporal Signal Profiles of Analytical Species in Modulated Glow Discharge Plasma. Anal. Chem. 1993, 65, 735–739.
Stedman, D. H.; Setser, D. W. Chemical Applications of Metastable Rare Gas Atoms. Prog. React. Kinet. 1971, 6, 193–238.
Smith, R. D.; Futrell, J. H. Reaxtions of Rear-Gas Hydride Ions with Ethylene. Int. J. Mass Spectrom. Ion Phys. 1976, 20, 71–76.
Hang, W.; Harrison, W. W. Diffusion Ionization and Sampling Processes in the Glow Discharge Source for Mass Spectrometry. Anal. Chem. 1997, 69, 4957–4962.
Ye, Y.; Marcus, R. K. Langmuir Probe Study of the Charged Particle Characteristics in an Analytical Radio Frequency Glow Discharge. Role of Discharge Conditions and Sample Conductivity. Spectrochim. Acta Part B 1996, 51, 509–531.
Lewis, C. L.; Li, L.; Millay, J. T.; Downey, S.; Warrick, J.; King, F. L. Temporal Emission Characteristics of Millisecond Pulsed Radiofrequency and Direct Current Glow Discharges. J. Anal. At. Spectrom. 2003, 18, 1–7.
Jackson, G. P.; King, F. L. Probing Excitation/Ionization Processes in Millisecond-Pulsed Glow Discharge in Argon Through the Addition of Nitrogen. Spectrochim. Acta 2003, 58B, 185–209.
King, F. L.; McCormack, A. L.; Harrison, W. W. Study of Molecular Interferences in Glow Discharge Mass Spectrometry. J. Anal. At. Spectrom. 1988, 3, 883–886.
Duckworth, D. C.; Marcus, R. K. Direct Insertion Probe for Radio Frequency Powered Glow Discharge Mass Spectrometry. J. Anal. At. Spectrom. 1992, 7, 711–715.
Guzowski, J. P.; Hieftje, G. M. Development of a Direct Current Gas Sampling Glow Discharge Ionization Source for the Time-of-Flight Mass Spectrometer. J. Anal. At. Spectrom. 1999, 14, 1121–1127.
Steers, E. B. M.; Fielding, R. J. Charge Transfer Excitation Processes in the Grimm Lamp. J. Anal. At. Spectrom. 1987, 2, 239–244.
Coburn, J. W.; Kay, E. Plasma Diagnostic of an rf-Sputtering Glow Discharge. Appl. Phys. Lett. 1971, 18, 435–438.
Author information
Authors and Affiliations
Corresponding author
Additional information
Published online November 19, 2003
Rights and permissions
About this article
Cite this article
Li, L., Millay, J.T., Turner, J.P. et al. Millisecond pulsed radio frequency glow discharge time of flight mass spectrometry: Temporal and spatial variations in molecular energetics. J Am Soc Mass Spectrom 15, 87–102 (2004). https://doi.org/10.1016/j.jasms.2003.09.004
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1016/j.jasms.2003.09.004