Abstract
The dependence of the Na2 electron impact ionization rate is measured as a function of vibrational excitation in a crossed molecule-electron beamm arrangement at collision energiesE coll ≤ 3 eV above the ionization threshold. Specific vibrational distributions in theX 1∑ + g state with average vibrational energies of 0.17 eV, 0.276 eV, and 0.349 eV, are prepared via Franck-Condon pumping using a narrow-band cw laser. Enhancement of the ionization rate is observed only at impact energies near the ionization threshold where the ionization rate increases linearly as a function of vibrational excitation. Analysis of the experimental data is based on three model calculations. The first of these calculations equates vibrational energy with kinetic energy and agrees well with the experimental data. A second, more refined model allows for differences in state-to-state ionization rates and uses Franck-Condon factors to estimate transition probabilities, but leads to a less favorable agreement. The third one employs a semi-classical formulation of the Franck-Condon principle. It provides the best agreement with the experimental data. In contrast with an earlier study of electron impact ionization of diatomic molecules [20], we find no evidence of dynamical modification of the ionization rate, due to vibrational motion of the nuclei, at the present level of accuracy of our data and analysis.
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Schlemmer, P., Rösel, T., Jung, K., Ehrhardt, H.: Phys. Rev. Lett.63, 252 (1989)
Schlemmer, P., Srivastava, M.K., Rösel, T., Ehrhardt, H.: J. Phys. B24, 2719 (1991)
Funk, H.: Ann. Phys.4, 140 (1930); Take J.T., Smith, P.T.: Phys. Rev.46, 773 (1934)
Brink, G.O.: Phys. Rev.134, A345 (1964)
McFarland, R.H., Kinney, J.D.: Phys. Rev.137, A1058 (1965)
Bushaw, B.A., Cannon, B.D., Gerke, G.K., Whitaker, T.J.: Opt. Lett.11, 422 (1986)
Trajmar, S., Nickel, J.C., Antoni, T.: Phys. Rev. A34, 5154 (1986)
Park, S.M., Diebold, G.J.: Opt. Commun.69, 253 (1989)
Jung, K., Schubert, E., Paul, D.A.L., Ehrhardt, H.: Phys. B: At. Mol. Phys.8, 1330 (1975)
McDaniel, E.W.: Atomic collisions: electron and photon projectiles, pp. 422–436, New York: Wiley 1989
Cacciatore, M., Capitelli, M. Dilonardo, M.: Chem. Phys.34, 193 (1978)
Fox, R.E., Hipple, J.A.: J. Chem. Phys.15, 208 (1947)
Foner, S.N., Hudson, R.L.: Chem. Phys. Lett.100, 559 (1983)
Jackson, W.M., Brackmann, R.T., Fite, W.L.: J. Mass Spectr.13, 237 (1974)
Bartoszek, F.E., Manos, D.M., Polanyi, J.C.: J. Chem. Phys.67, 3395 (1977)
Foner, S.N., Hudson, R.L.: J. Chem. Phys.80, 518 (1984)
Rubahn, H.-G., Toennies, J.P., Wilde, M.: Chem. Phys. Lett.120, 11 (1985)
Akulin, V.M., Vurdov, V.D., Esadze, G.G., Karlov, N.V., Prokhorov, A.M., Susanin, A.A., Khokhlov, E.M.: JETP Lett.40, 783 (1984)
Bergmann, K., Hefter, U., Witt, J.: J. Chem. Phys.72, 4777 (1980); Bergmann, K.: In: Atomic and molecular beam methods. Scoles, G. (ed.) Chap. 12. Oxford: Oxford University Press 1988
Fuchs, M. Toennies, J.P.: J. Phys. B20, 605 (1987)
Thomson, J.J.: Philos. Mag.23, 449 (1912)
Henriet, A., Masnou-Seeuws, F.: J. Phys. B23, 219 (1990)
Henriet, A.: J. Phys. B18, 3085 (1985)
Bergman, K., Hefter, U., Hering, P.: Chem. Phys.32, 329 (1978)
Collins, R.E., Aubrey, B.B., Eisner, P.N., Celotta, R.J.: Rev. Sci. Instrum.41, 1403 (1970)
Wiley, W.C., McLaren, I.H.: Rev. Sci. Instrum.26, 1150 (1955)
Wannier, G.H.: Phys. Rev.90, 817 (1953)
Bordas, C., Labastie, P., Chevaleyre, J., Broyer, M.: Chem. Phys.129, 21 (1989)
Barrow, R., Verges, J., Effantin, C., Hussein, K., d'Incon, J.: Chem. Phys. Lett.104, 179 (1984)
Korsch, H.J., Laurent, H.: J. Phys. B14, 4213 (1981); J. Stoer, Numerische Mathematik, 3rd edn., Vol. 2., Berlin, Heidelberg, New York: Springer 1980
Kusch, P., Hessel, M.M.: J. Chem. Phys68, 2591 (1978)
Gerber, G., Möller, R.: Chem. Phys. Lett.113, 546 (1985)
Schmidt, I.: Dissertation, p. 133. Chemistry Dept., Universität Kaiserslautern, 1987
McDaniel, E.W.: Atomic collisions: electron and photon projectiles, pp. 556–557, New York: Wiley 1989
Kaminsky, M.: J. Chem. Phys.66, 4951 (1977);73, 3520 (1980)
Bähring, A., Hertel, I.V., Meyer, E., Meyer, W., Spies, N., Schmidt, H.: J. Phys. B17, 2859 (1984)
Noda, C., Zare, R.N.: J. Mol. Spectrosc.95, 254 (1982)
Mulliken, R.S.: J. Chem. Phys.55, 309 (1971)
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Külz, M., Kortyna, A., Keil, M. et al. On the vibrational dependence of electron impact ionization of diatomic molecules. Z Phys D - Atoms, Molecules and Clusters 33, 109–117 (1995). https://doi.org/10.1007/BF01437429
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DOI: https://doi.org/10.1007/BF01437429