EII of plasma edge constituents, properties of Be x H y molecules S. Matejcik, P. Mach, J. Urban Comenius University Bratislava Slovakia

Bratislava

Overview - Appearance energies of C 2 D 6 - Cross section for EII to propane - BeH and BeH 2 – structure and energies - Structure and energetics of Be m H n clusters

Electron impact ionization cross sections (total, partial) ionization energies appearance energies kinetic energy release gas temperature dependencies products of the reactions

Experimental setup

Cross section measurements Absolute measurement of the pressure Relative flow technique Ar as a calibration gas

Atoms: Wannier theory:  w (E,AE,A,d) = 0 E<AE A(E-IE) d E>AE d=1.127 Threshold behaviour of the cross sections f(E,U) - EEDF Fitting function:

d=1.127±0.01 Threshold behaviour of the cross sections

CH 3 D AE (eV) 293 K CD 4 AE (eV) 293 K CH 4 AE (eV) 293 K CH 3 D ± ± ± 0.04CH 4 + CH 2 D + + H – CH 2 D + + H ± ± ± ± ± 0.1 CH H – CH H Isotopic effect on AE Denifl et al. IJMS 248 (2005) 29

Present meV a) meV b) meV (CH 3 D) + /CH 3 D10050 (CH 2 D) + /CH 3 D80 (CH 3 ) + /CH 3 D200 (CHD) + /CH 3 D110 (CD 4 ) + /CD (CD 3 ) + /CD (CD 2 ) + /CD a) F. P. Lossing, A. W. Tickner, W. A. Bryce, J. Chem. Phys. 19, 1254 (1951). b) V. H. Dibeler, M. Krauss, R. M. Reese, F. N. Harlee J. Chem. Phys. 42, 3791 (1965). Isotopic shift Denifl et al. IJMS 248 (2005) 29

EII of C 2 D 6 e + C 2 D 6 → C 2 D e → C 2 D D – + 2e → C 2 D D 2 + e

EII to C 2 D 6

Izotopic effects in C 2 D 6 a E. Vaseková, M. Stano, S. Matejcik,, J.D. Skalný, P. Mach, T.D. Märk, J. Urban Int. J. of Mass Spect., 235 (2004) e + C 2 D 6 →AE (in eV) PresentEthan a ( C 2 D 6 ) ± ± 0.06 ( C 2 D 5 ) ± 0.07 ?12.06± 0.03 ( C 2 D 4 ) ± ± 0.04 ( C 2 D 2 ) ± ± 0.2

Grill et al. ZPhysD 25 (1993) 217

EII to C 3 H 8

Appearance energies C 3 H 8 Denifl CPL 402 (2005) 80

EII to C 3 H 8 cross sections Exp: N. Duric, I. Čadež, M. Kurepa, Int. J. Mass Spectrom. & Ion Processes, 108 (1991) R1-R10.

Total cross sections σ BEB (12 eV)σ Present (12 eV)σ Exp (12 eV) [ cm 2 ] Exp: N. Duric, I. Čadež, M. Kurepa, Int. J. Mass Spectrom. & Ion Processes, 108 (1991) R1-R10. BEB: W. Hwang, Y.-K. Kim and M.E. Rudd, J. Chem. Phys., 104 (1996) 2956

Cross sections at 700 K Not finnished yet Problems with contamination

EII to Be x H y Experimental problems Vaporisation only at T>1000°C Toxicity of Be

BeH dissoc. energy CCSDT-R12 1exc. energy 2 Σ – 2 Π, experiment cm -1, theory – cm -1

BeH bond lenght

BeH 2 basisBeH 2 Be-H [A] TAE a) [eV] DE Be+H2 [eV] CCSD(T)- R12 Be:19s14p8d6f4g H: 9s,6p,4d,3f CCSD(T) Full aug-cc-pCvDZ aug-cc-pCvTZ aug-cc-pCvQZ aug-cc-pCv5Z B3LYP G(3d,3p) aug-cc-pCv5Z

BeH 2 bond lenght

Be n H clusters – MP2

Be n H 1

Be 3 H n Be 4 H n

Futher plans Propane cross section at high T C 2 D 6 – high T, cross sections Ionization energies of the Be compounds Appearance energies of the fragments Simulation of the Be surface Chemistry on the Be surface

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