Electron Attachment to Excited Molecules

  • Loucas G. Christophorou
  • Lal A. Pinnaduwage
  • Panos G. Datskos
Part of the NATO ASI Series book series (NSSB, volume 326)

Abstract

Studies on electron attachment to molecules rotationally/vibrationally excited thermally or via infrared-laser excitation showed that the effect of internal energy of a molecule on its electron attachment properties depends on the mode-dissociative or nondissociative-of electron attachment. They quantified the effect of the internal energy of the molecule on the rate of destruction (by autodissociation or by autodetachment) of its parent transient anion. Generally, increases in ro-vibrational molecular energy increase the cross section for dissociative electron attachment and decrease the effective cross section for parent anion formation due mainly to increased autodetachment. These findings and their understanding are discussed. A discussion is given, also, of recent investigations of electron attachment to electronically excited molecules, especially photoenhanced dissociative electron attachment to long- and short-lived excited electronic states of molecules produced directly or indirectly by laser irradiation. These studies showed that the cross sections for dissociative electron attachment to electronically excited molecules usually are many orders of magnitude larger than those for the ground-state molecules. The new techniques that have been developed for such studies are briefly described also.

Keywords

Microwave Polycyclic Aromatic Hydrocarbon Disulfide Benzoquinone Deuterium 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Christophorou, L. G., “Atomic and Molecular Radiation Physics,” Wiley-Interscience, New York (1971).Google Scholar
  2. 2.
    Massey, H.S.W., “Negative Ions,” Cambridge University Press, London (1976).Google Scholar
  3. 3.
    Smirnov, B. M., “Negative Ions,” McGraw-Hill New York (1982).Google Scholar
  4. 4.
    Christophorou, L. G., McCorkle, D. L., and Christodoulides, A. A., Electron Attachment Processes, in “Electron Molecule Interactions and Their Applications,” L. G. Christophorou (Ed.), Academic Press, New York, 1984, Vol. 1, Chapt. 6.Google Scholar
  5. 5.
    Klar, D., Ruf, M.-W., and Hotop, H., Attachment of Electrons to Molecules at meV Resolution, Austr. J. Phys. 45:263 (1992).ADSCrossRefGoogle Scholar
  6. 6.
    Illenberger, E., Electron-Attachment Reactions in Molecular Clusters, Chem. Rev. 92:1589 (1992).CrossRefGoogle Scholar
  7. 7.
    Christophorou, L.G., Electron Attachment and Detachment Processes in Electronegative Gases, Cotrib. Plasma Phys. 27:237 (1987).Google Scholar
  8. 8.
    Christophorou, L. G., Electron-Excited Molecule Interactions, in “Invited Papers, Proc. XXth Intern. Conf. Ionization Phenomena in Gases,” V. Palleschi, D. P. Singh, and M. Vaselli (Eds.), Institute of Atomic and Molecular Physics, CNR, Pisa, Italy, July 8–12, 1991, pp. 3–13.Google Scholar
  9. 9.
    Christophorou, L. G., The Lifetimes of Metastable Negative Ions, Adv. Electr. Electron Phys., 46:55 (1978).CrossRefGoogle Scholar
  10. 10.
    Allan, M. and Wong, S. F., Effect of Vibrational and Rotational Excitation on Dissociative Attachment to Hydrogen, Phys. Rev. Lett. 41:1791 (1978).ADSCrossRefGoogle Scholar
  11. (b).
    Dissociative Attachment from Vibrational and Rotationally Excited HCl and HF, J. Chem. Phys. 74:1687 (1981).ADSCrossRefGoogle Scholar
  12. 11.
    Spyrou, S. M., and Christophorou, L. G., Effect of Temperature on the Dissociative Electron Attachment to CClF3 and C2F6 J. Chem. Phys. 82:2620 (1985).ADSCrossRefGoogle Scholar
  13. 12.
    Chantry, P. J. and Chen, C. L., Ionization and Temperature Dependent Attachment Cross Section Measurements in C3F8 and C2H3C1, J. Chem. Phys. 90:2585 (1989).ADSCrossRefGoogle Scholar
  14. 13.
    Datskos, P. G. and Christophorou, L. G., Variation with Temperature of the Electron Attachment to SO2F2, J. Chem. Phys. 90:2626 (1989).ADSCrossRefGoogle Scholar
  15. 14.
    Datskos, P. G., Christophorou, L. G., and Carter, J. G., (a) Temperature Enhanced Electron Attachment to CH3C1, Chem. Phys. Lett. 168:324 (1990).ADSCrossRefGoogle Scholar
  16. (b).
    Effect of Temperature on the Attachment of Slow (≲ 1 eV) Electrons to CH3Br, J. Chem. Phys. 97:9031 (1992).ADSCrossRefGoogle Scholar
  17. 15.
    O’Malley, T. F., Calculation of Dissociative Attachment to Hot O2, Phys. Rev. 155:59 (1967).ADSCrossRefGoogle Scholar
  18. 16.
    Bardsley, J. N. and Wadehra, J. M., (a) Dissociative Attachment and Vibrational Excitation in Low- Energy Collisions of Electrons with H2 and D2, Phys. Rev. A 20:1398 (1979).ADSCrossRefGoogle Scholar
  19. (b).
    Dissociative Attachment to HCl, DCl, and F2, J. Chem. Phys. 78:7227 (1983).ADSCrossRefGoogle Scholar
  20. 17.
    Teillet-Billy, D. and Gauyacq, J. P., Dissociative Attachment in e-HCl, DCl Collisions, J. Phys. B 17:4041 (1984).ADSCrossRefGoogle Scholar
  21. 18.
    Hickman, A.P., Dissociative Attachment of Electrons to Vibrationally Excited H2, Phys. Rev. A 43:3495 (1991).ADSCrossRefGoogle Scholar
  22. 19.
    Spyrou, S. M. and Christophorou, L. G., (a) Effect of Temperature on Nondissociative Electron Attachment to Perfluorobenzene, J. Chem. Phys. 82:1048 (1985).ADSCrossRefGoogle Scholar
  23. (b).
    Effect of Temperature on the Dissociative and Nondissociative Electron Attachment to C3F8, J. Chem. Phys. 83:2829 (1985).ADSCrossRefGoogle Scholar
  24. 20.
    Adams, N. G., Smith, D., Alge, E., and Burdon, J., Anomalous Temperature Dependence of the Coefficient of Electron Attachment to Hexafluorobenzene, Chem. Phys. Lett. 116:460 (1985).ADSCrossRefGoogle Scholar
  25. 21.
    Christodoulides, A.A., Christophorou, L. G., and McCorkle, D. L., Effect of Temperature on the Low- Energy (≲ 1 eV) Electron Attachment to Perfluorobutane (c-C4F8), Chem. Phys. Lett. 139:350 (1987).ADSCrossRefGoogle Scholar
  26. 22.
    Datskos, P. G., Christophorou, L. G., and Carter, J. G., (a) Temperature Enhanced Electron Detachment From C6F6 Negative Ions, J. Chem. Phys. 98:7875 (1993).ADSCrossRefGoogle Scholar
  27. (b).
    Temperature Dependence of Electron Attachment and Detachment in SF6 and c-C4F6, J. Chem. Phys. (submitted).Google Scholar
  28. 23.
    (a) Alge, E., Adams, N. G., and Smith, D., Rate Coefficients for the Attachment Reactions of Electrons with c-C7F14, CH3Br, CF3Br, CH2Br2, and CH3I Determined Between 200 and 600 K Using the FALP Technique, J. Phys. B 17:3827 (1984).ADSCrossRefGoogle Scholar
  29. 24.
    Chen, C. L. and Chantry, P. J., Photon-Enhanced Dissociative Electron Attachment in SF6 and Its Isotopic Selectivity, J. Chem. Phys. 71:3897 (1979).ADSCrossRefGoogle Scholar
  30. 25.
    Hunter, S. R., Carter, J. G., and Christophorou, L. G., Electron Transport Measurements in Methane Using an Improved Townsend Technique, J. Appl. Phys. 60:24 (1986).ADSCrossRefGoogle Scholar
  31. 26.
    Wen, C. and Wetzer, J.M., Electron Avalanches Influenced by Detachment and Conversion Processes, IEEE Trans. Electr. Insul. 23:999 (1988).CrossRefGoogle Scholar
  32. (b).
    Time-Resolved Avalanches Current Waveforms in Octafluorocyclobutane, IEEE Trans. Electr. Insul. 24:143 (1989).CrossRefGoogle Scholar
  33. 27.
    Chowdhury, S., Grimsrud, E. P., Heinis, T., and Kebarle, P., Electron Affinities of Perfluorobenzene and Perfluorophenyl Compounds, J. Am. Chem. Soc. 108: 3630 (1986).CrossRefGoogle Scholar
  34. 28.
    Knighton, W. B., Bognar, J. A., and Grimsrud, E. P., Thermal Electron Detachment Rate Constants for the Molecular Anion of Perfluorobenzene, Chem. Phys. Lett. 192:522 (1992).ADSCrossRefGoogle Scholar
  35. 29.
    Rossi, M. J., Helm, H., and Lorents, D. C., Photoenhanced Electron Attachment to Vinylchloride and Trifluoroethylene at 193 nm, Appl. Phys. Lett. 47:576 (1985).ADSCrossRefGoogle Scholar
  36. 30.
    Schulz, G. J., Resonances in Electron Impact on Diatomic Molecules, Rev. Mod. Phys. 45:423 (1973).ADSCrossRefGoogle Scholar
  37. 31.
    (a) Christophorou, L. G., Carter, J. G., and Christodoulides, A. A., Long-Lived Parent Negative Ions in p-Benzoquinone Formed by Electron Capture in the Field of the Ground and Excited States, Chem. Phys. Lett. 3:237 (1969).ADSCrossRefGoogle Scholar
  38. (b).
    Collins, P. M., Christophorou, L.G., Chaney, E. L., and Carter, J. G., Energy Dependence of the Electron Attachment Cross Section and the Transient Negative Ion Lifetime for p-Benzoquinone and 1,4-Naphthoquinone, Chem. Phys. Lett. 4:646 (1970).ADSCrossRefGoogle Scholar
  39. 32.
    Tobita, S., Meinke, M., Illenberger, E., Christophorou, L. G., Baumgartel, H., and Leach, S., Polycyclic Aromatic Hydrocarbons: Negative Ion Formation Following Low Energy (0–15 eV) Electron Impact, Chem. Phys. 161:501 (1992).CrossRefADSGoogle Scholar
  40. 33.
    Pinnaduwage, L. A., Christophorou, L. G., and Bitouni, A. P., Enhanced Electron Attachment to Superexcited States of Saturated Tertiary Amines, J. Chem. Phys. 95:274 (1991).ADSCrossRefGoogle Scholar
  41. 34.
    Pinnaduwage, L. A., Christophorou, L. G., and Hunter, S. R., Optically Enhanced Electron Attachment to Thiophenol, J. Chem. Phys. 90:6275 (1989).ADSCrossRefGoogle Scholar
  42. 35.
    Pinnaduwage, L. A. and Christophorou, L. G., Verification of IT Formation in UV Laser Irradiated Hydrogen; Implication for Negative Ion and Neutral Beam Technology, J. Appl. Phys. (submitted, 1993).Google Scholar
  43. 36.
    Jaffke, T., Hashemi, R., Christophorou, L. G., Illenberger, E., Baumgartel, H., and Pinnaduwage, L. A., Photoenhanced Dissociative Electron Attachment to SO2, Chem. Phys. Lett. 203:21 (1993).ADSCrossRefGoogle Scholar
  44. 37.
    Pinnaduwage, L. A. and Christophorou, L. G., Enhanced Electron Attachment to Superexcited States of Nitric Oxide, Chem. Phys. Lett. 186:4 (1991); erratum 189:486 (1992).ADSCrossRefGoogle Scholar
  45. 38.
    Burrow, P. D., Dissociative Attachment From the O2(a 1Δg) State, J. Chem. Phys. 59:4922 (1973).ADSCrossRefGoogle Scholar
  46. 39.
    Belić, D. S. and Hall, R.I., Dissociative Electron Attachment to Metastable Oxygen (a 1Δg), J. Phys. B 14:365 (1981).ADSCrossRefGoogle Scholar
  47. 40.
    Jaffke, T., Meinke, M., Hashemi, R., Christophorou, L. G., and Illenberger, E., Dissociative Electron Attachment to Singlet Oxygen, Chem. Phys. Lett. 193:62 (1992).ADSCrossRefGoogle Scholar
  48. 41.
    Christophorou, L. G., Hunter, S. R., Pinnaduwage, L. A., Carter, J. G., Christodoulides, A. A., and Spyrou, S. M., Optically Enhanced Electron Attachment, Phys. Rev. Lett. 58:1316 (1987).ADSCrossRefGoogle Scholar
  49. 42.
    Kuo, C. T., Ono, Y., Hardwick, J. L., and Moseley, J. T., Dissociative Attachment of Electrons to the A 2+ State of Nitric Oxide, J. Phys. Chem. 92:5072 (1988).CrossRefGoogle Scholar
  50. 43.
    Mock, R. S. and Grimsrud, E. P., Optically Enhanced Electron Capture by p-Benzoquinone and Its Methylated Derivatives, J. Phys. Chem. 94:3550 (1990).CrossRefGoogle Scholar
  51. 44.
    Spyrou, S. M., Sauers, I., and Christophorou, L. G., Dissociative Electron Attachment to SO2, J. Chem. Phys. 84:239 (1986).ADSCrossRefGoogle Scholar
  52. 45.
    Okabe, H., “Photochemistry of Small Molecules,” Wiley, New York, (1978).Google Scholar
  53. 46.
    Miller, J. C. and Compton, R. N., Multiphoton Ionization Studies of Ultracold Nitric Oxide, J. Chem. Phys. 84:675 (1986).ADSCrossRefGoogle Scholar
  54. 47.
    Pinnaduwage, L. A. and Christophorou, L. G., H Formation in Laser-Excited Molecular Hydrogen, Phys. Rev. Lett. 70:754 (1993).ADSCrossRefGoogle Scholar
  55. 48.
    Christophorou, L. G. and Illenberger, E., Scattering of Slow Electrons From Excited Atoms: The Dominant Role of the Polarization Potential, Phys. Lett. A. 173:78 (1993).ADSCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 1994

Authors and Affiliations

  • Loucas G. Christophorou
    • 1
    • 2
  • Lal A. Pinnaduwage
    • 1
    • 2
  • Panos G. Datskos
    • 1
    • 2
  1. 1.Atomic, Molecular, and High Voltage Physics Group, Health and Safety Research DivisionOak Ridge National LaboratoryOak RidgeUSA
  2. 2.Department of PhysicsThe University of TennesseeKnoxvilleUSA

Personalised recommendations