Spin Exchange In Elastic E-o2 Collisions

Recent experiments using polarized electron beams have shown that spin-exchange effects for elastic collisions with O2 and NO are much smaller than for Na atoms. We report calculated spin-flip differential cross sections for elastic collisions of polarized electrons with O2 in agreement with experiment. In general, we can attribute large variations of the spin-flip differential cross sections to resonances and interference effects. Such features arising from interference, however, may be washed out in the molecular case due to the average over orientations. Calculations with oriented O2 show strong exchange effects as for Na.68111698170

Superelastic Cross Sections In E--h2 Scattering

We present superelastic cross sections of H2 by electron impact. Our results, obtained with the Schwinger multichannel method, include cross sections for the c 3Πu→ X 1Σg (+), c 3Πu→ b 1Σu (+), c 3Πu→ a 3Σg (+), and elastic c 3Πu→ c 3Πu transitions. The calculated cross sections are very large, indicating their importance in the modeling of discharge environments. We also investigate the dependence of these cross sections on the internuclear separation of the H atoms and on different approximations of the target wave function. To assess the role of the exchange potential in these processes, we also present the corresponding polarization fractions.55432433246Garscadden, A., (1992) Z. Phys. D, 24, p. 97Pinnaduwage, L.A., Christoforou, L.G., (1993) Phys. Rev. Lett., 70, p. 754Pinnaduwage, L.A., Christoforou, L.G., (1994) J. Appl. Phys., 76, p. 46Allan, M., Wong, S.F., (1978) Phys. Rev. Lett., 41, p. 1791Wadehra, J.M., Bardsley, J.N., (1978) Phys. Rev. Lett., 41, p. 1795Buckman, S.J., Elford, M.T., Newman, D.S., (1987) J. Phys. B, 20, p. 5175Christoforou, L.G., Datskos, P.G., Carter, J.G., (1991) Chem. Phys. Lett., 186, p. 11Burrow, P.D., Davidovits, P., (1968) Phys. Rev. Lett., 21, p. 1789Hall, R.I., Trajmar, S., (1975) J. Phys. B, 8, pp. L293Christoforou, L.G., Illenberger, E., (1993) Phys. Lett. A, 173, p. 78Capitelli, M., Colonna, G., Hassouni, K., Gicquel, A., (1994) Chem. Phys. Lett., 228, p. 687Takatsuka, K., McKoy, V., (1981) Phys. Rev. A, 24, p. 2473Beutler, H., Deubner, A., Junger, H.O., (1935) Z. Phys., 98, p. 181Gillan, C.J., Nagy, O., Burke, P.G., Morgan, L.A., Noble, C.J., (1987) J. Phys. B, 20, p. 4585Rescigno, T.N., McCurdy, C.W., Schneider, B.I., (1989) Phys. Rev. Lett., 63, p. 248Da Paixão, F.J., Lima, M.A.P., McKoy, V., (1992) Phys. Rev. Lett., 68, p. 1698Da Paixão, F.J., Lima, M.A.P., McKoy, V., (1996) Phys. Rev. A, 53, p. 1400Ferreira, L.G., private communicationBettega, M.H.F., Natalense, A.P.P., Lima, M.A.P., Ferreira, L.G., (1996) Int. J. Quantum Chem., 60, p. 821Goddard III, W.A., Hunt, W.J., (1974) Chem. Phys. Lett., 24, p. 464Lima, M.A.P., Gibson, T.L., McKoy, V., Huo, W.M., (1988) Phys. Rev. A, 38, p. 4527Steven, D., Parker, C., McCurdy, W., Rescigno, T.N., Lengsfield III, B.H., (1991) Phys. Rev. A, 43, p. 3514Linder, F., Schmidt, H., (1971) Z. Naturforsch. Teil A, 26, p. 1603Srivastava, S.K., Chatujian, A., Trajmar, S., (1975) J. Chem. Phys., 63, p. 2659Hegeman, T., Oberste-Vorth, M., Vogts, R., Hanne, G.F., (1991) Phys. Rev. Lett., 66, p. 2968Nordbeck, R.-P., Fullerton, C.M., Woeste, G., Thompson, D.G., Blum, K., (1994) J. Phys. B, 27, p. 537

Immobilization And Photoacoustic Spectroscopy Of N-(2-pyridyl)acetamide Cation Complexes Bonded To Silica Gel

N-(2-Pyridyl)acetamide was covalently immobilized onto silica gel giving 1.57×10-4 mol of this molecule per gram of silica. This new bidentate chelate extracts MCl2 (M = Ni, Co, Cu) from ethanol and acetone solutions. The photoacoustic spectra of the solid complexed samples were obtained in the visible and near-infrared spectral regions and were analysed using ligand field theory. The calculated Racah parameters indicate a tetrahedral geometry for nickel and cobalt and a highly distorted octahedral geometry for the copper complex.3547948213SDG16840035; AHA; American Heart Associatio

Electron Impact Excitation Of The Metastable He(2 3s)

The first-order many-body theory is applied to study the inelastic collision of unpolarized electrons with helium in the 2 3S excited state. The authors calculate differential cross sections (DCS) and integral cross sections (ICS) for 2 3S → 2 3P, 3 3S, 3 3P transitions and the alignment and orientation parameters for the 2 3S to 2 3P, 3 3P transitions. The calculated DCS for the transition 2 3S→ 2 3P is in good agreement with published theoretical and experimental results. The general behaviour of the alignment and orientation parameters for He 2 3S→ 2 3P transition is compared with that of the Na 3 2S → 3 2P transition. © 1994 IOP Publishing Ltd.2781577158

Electron-impact Excitation Of H2: Minimal Orbital Basis For Single Configuration Interaction

We report theoretical differential excitation cross sections for scattering of electrons by H2 molecules using the Schwinger multichannel approach (SMC). This study differs from previous applications of the SMC method in the description of the excited states (which are now obtained through the single configuration interaction technique) and in the level of the multichannel coupling. The calculation is performed with singlet and triplet states present in the manifold. The results given by this strategy show a significant improvement to experimental data in comparison with earlier two-state close coupling calculations.376L129L135Trajmar, S., Cartwright, D.C., Rice, J.K., Brinkmann, R.T., Kupperman, A., (1968) J. Chem. Phys., 49, p. 5464Weingartshofer, A., Ehrhardt, H., Hermann, V., Linder, F., (1970) Phys. Rev. A, 2, p. 294Hall, R.I., Andric, L., (1984) J. Phys. B: At. Mol. Phys., 17, p. 3815Nishimura, H., Danjo, A., (1986) J. Phys. Soc. Japan, 55, p. 3031Khakoo, M.A., Trajmar, S., McAdams, K., Shyn, T.W., (1987) Phys. Rev. A, 35, p. 2832Khakoo, M.A., Segura, J., (1994) J. Phys. B: At. Mol. Opt. Phys., 27, p. 2355Khakoo, M.A., Trajmar, S., (1986) Phys. Rev. A, 34, p. 138Srivastava, S., Jansen, S., (1977) J. Phys. B: At. Mol. Phys., 10, p. 3341Khakoo, M.A., Trajmar, S., (1986) Phys. Rev. A, 34, p. 146Wrkich, J., Mathews, D., Kanik, I., Trajmar, S., Khakoo, M.A., (2002) J. Phys. B: At. Mol. Opt. Phys., 35, p. 4695Baluja, K.L., Noble, C.J., Tennyson, J., (1985) J. Phys. B: At. Mol. Phys., 18, pp. L851Schneider, B.I., Collins, L., (1985) J. Phys. B: At. Mol. Phys., 18, pp. L857Lima, M.A.P., Gibson, T.L., Takatsuka, K., McKoy, V., (1985) J. Phys. B: At. Mol. Phys., 18, pp. L865Gibson, T.L., Lima, M.A.P., McKoy, V., Huo, W.M., (1987) Phys. Rev. A, 35, p. 2473Rescigno, T.N., Schneider, B.I., (1988) J. Phys. B: At. Mol. Opt. Phys., 21, pp. L961Lima, M.A.P., Gibson, T.L., McKoy, V., Huo, W., (1988) Phys. Rev. A, 38, p. 4527Parker, S.D., McCurdy, C.W., Rescigno, T.N., Lengsfield III, B.H., (1991) Phys. Rev. A, 43, p. 3514Machado, A.M., Fujimoto, M.M., Taveira, A.M.A., Brescansin, L.M., Lee, M.T., (2001) Phys. Rev. A, 63, p. 0032707Goddard III, W.A., Hunt, W.J., (1974) Chem. Phys. Lett., 24, p. 464Machado, A.M., Taveira, A.M.A., Brescansin, L.M., Lee, M.T., (2001) J. Mol. Struct., 574, p. 133Branchett, S.E., Tennyson, J., Morgan, L.A., (1991) J. Phys. B: At. Mol. Opt. Phys., 24, p. 3479Trevisan, C.S., Tennyson, J., (2001) J. Phys. B: At. Mol. Opt. Phys., 34, p. 2935Takatsuka, K., McKoy, V., (1981) Phys. Rev. A, 24, p. 2473Lippmann, B.A., Schwinger, J., (1950) Phys. Rev., 79, p. 469Lima, M.A.P., McKoy, V., (1988) Phys. Rev. A, 38, p. 501Rodberg, L.S., Thaler, R.M., (1970) Introduction of Quantum Theory of Scattering, p. 299. , New York: AcademicKolos, W., Wolniewicz, L., (1965) J. Chem. Phys., 43, p. 2429Kolos, W., Wolniewicz, L., (1968) J. Chem. Phys., 48, p. 3672Kolos, W., Rychlewski, J., (1977) J. Mol. Spectrosc., 66, p. 428Kolos, W., Dresser, K., (1985) J. Chem. Phys., 82, p. 3292Rothenberg, S., Davidson, E.R., (1966) J. Chem. Phys., 44, p. 730Sharp, T.E., (1971) At. Data, 2, p. 119Lee, M.T., Taveira, A.M.A., Fujimoto, M.M., Machado, L.E., Brescansin, L.M., (1997) J. Mol. Struct., 394, p. 12

Unitarized First-order Many-body Approximation For The Electron Impact Excitation Of Triplet States Of Helium

We use unitarized first-order many-body theory (UFMB) to obtain differential cross sections for the electron impact excitation of the 2 3S and 2 3P states of helium in the intermediate energy range. Our results are in much better agreement with experiment than previous calculations using the weak-coupling approach. © 1994 1OP Publishing Ltd.2711L265L26

Frame Transformation Relations And Multipole Transitions In Symmetric Polyatomic Molecules

The theory of transformation relations between states of Born Oppenheimer and weak coupling approximations is developed for polyatomic molecules. The relations are a generalization of frame transformation relations used by Chang and Fano for symmetric-top molecules, and they lead to a more convenient symmetry labeling system than was previously available. A key internal symmetry label (named "soul") is defined so that it remains a constant label for frame transformation relations, and is conserved during vibronic transitions, ionization, and even dissociation provided the nuclear spin-rotation interaction is relatively small. Various nomograms, graphs, and tableaus associated with the soul label make it easy to predict and visualize the form of many types of complex high-resolution spectra. Simplified procedures are given for obtaining selection rules, statistical weights, and matrix elements of multipole operators for common molecules having various point symmetries. Simplifications of computational theory using the new level cluster bases for high J are discussed. © 1978 American Physical Society.501378

Transitions Between Excited Electronic States Of H2 Molecules By Electron Impact

We present theoretical integral and differential cross sections for transitions produced by electron collision with an excited H2 molecule (c3Πμ and a3Σg (+)) obtained with the Schwinger multichannel method in a four-state approximation. We also present the transition rates obtained with these cross sections. The results indicate the importance of these scattering processes in modeling H2 discharge

Superelastic Collisions Of Electrons With The C 3Πu Metastable State In Hydrogen Dc Positive Column

We investigated the effect of superelastic electronic collisions of electrons, with the c 3Πu state of the H2 molecule, on the electron energy distribution function (eedf) of a dc positive column. We use a recently calculated set of electronic superelastic collision cross-sections [C.S. Sartori, F.J. da Paixão, M.A.P. Lima, Phys. Rev. A 55 (1997) 3243] to study the effect of these collisions on the eedf, the transport parameters, ionization and dissociation rates. We include two possible pathways, c 3Πu → b 3Σ+ u and c 3Πu → X 1Σ+ g, for superelastic collisions of electrons with molecules in the metastable state. Cross-sections of the order of 10-14 cm2 at low energy enhance the eedf tail by superelastic electronic collisions, in particular for low reduced electric field E/N. This result changes considerably the dissociation and ionization rates by six orders of magnitude in the region from 10 to 50 Td.2461-3275282Grill, A., (1994) Cold Plasma in Materials Fabrication, , IEEE Press, New YorkCapitelli, M., Dilonardo, M., (1979) Z. Naturforsch., 34, p. 585Capitelli, M., Colonna, G., Hassouni, K., Gicquel, A., (1994) Chem. Phys. Lett., 228, p. 687Sartori, C.S., Da Paixão, F.J., Lima, M.A.P., (1997) Phys. Rev. a, 55, p. 3243Freis, R.P., Hishes, J.R., (1970) Phys. Rev. a, 2, p. 573Weeding, A.B., Phelps, A.V., (1988) J. Chem. Phys., 89, p. 2965Bonnie, J.H.M., Eenshuistra, P.J., Hopman, H.J., (1986) Phys. Rev. Lett., 26, p. 3265Catherinot, A., Dubreil, B., Gand, M., (1978) Phys. Rev. a, 18, p. 1097Takatsuka, K., McKoy, V., (1981) Phys. Rev. a, 24, p. 2473Amorim, J., Loureiro, J., Baravian, G., Touzeau, M., (1997) J. Appl. Phys., 82, p. 2795Rapp, D., Englander-Golden, P., (1965) J. Chem. Phys., 43, p. 1464Phelps, A.V., (1990) J. Phys. Chem. Ref. Data, 19, p. 653Frost, L.S., Phelps, A.V., (1962) Phys. Rev., 127, p. 1621Loureiro, J., Ferreira, C.M., (1989) J. Phys. D: Appl. Phys., 22, p. 1680Hishes, J.R., (1980) J. Appl. Phys., 51, p. 4592Wadehra, J.M., Bardsley, J.N., (1978) Phys. Rev. Lett., 41, p. 1795Bardsley, J.N., Wadehra, J.M., (1979) Phys. Rev. a, 20, p. 1398Peart, B., Walton, D.S., Dolder, K.T., (1970) J. Phys. B, 3, p. 1346Peart, B., Dolder, K.T., (1974) J. Phys. B, 7, p. 236Gorse, C., Capitelli, M., Bretagne, J., Bacal, M., (1985) Chem. Phys., 93, p. 1Loureiro, J., Amorim, J., (1998) Chem. Phys., 232, p. 141Gorse, C., Capitelli, M., Bacal, M., Bretagne, J., Laganà, A., (1987) Chem. Phys., 117, p. 177Amorim, J., (1994), Ph.D. Thesis, University of Paris, Orsa