Post on 04-Jan-2016
EII of plasma edge constituents, properties of BexHy molecules
S. Matejcik, P. Mach, J. Urban
Comenius UniversityBratislavaSlovakia
Bratislava
Overview
- Appearance energies of C2D6
- Cross section for EII to propane
- BeH and BeH2 – structure and energies
- Structure and energetics of BemHn 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>AEd=1.127
Threshold behaviour of the cross sections
dEUEfAdAEEAdAEEI w ),(),,,(),,,(0
f(E,U) - EEDF
Fitting function:
23,5 24,0 24,5 25,0 25,5
0
100
200
300
400
500
He+/He
Ion
yiel
d (a
rb.
units
)
E (eV)
d=1.127±0.01
Threshold behaviour of the cross sections
CH3D
AE (eV)293 K
CD4
AE (eV)293 K
CH4
AE (eV)293 K
CH3D+ 12.75 ± 0.03 12.89 ± 0.03 12.65 ± 0.04 CH4
+
CH2D+ + H–
CH2D+ + H
13.66 ± 0.07 14.42 ± 0.05
- 14.54 ± 0.05
13.58 ± 0.1 14.34 ± 0.1
CH3+ + H–
CH3+ + H
Isotopic effect on AE
Denifl et al. IJMS 248 (2005) 29
PresentmeV
a)meV
b)meV
(CH3D)+/CH3D 100 50
(CH2D)+/CH3D 80
(CH3)+/CH3D 200
(CHD)+/CH3D 110
(CD4)+/CD4 190 170 160
(CD3)+/CD4 200 130
(CD2)+/CD4 310 90
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 C2D6
e + C2D6 → C2D6+ + 2e
→ C2D5+ + D– + 2e
→ C2D2+ + 2D2 + e
EII to C2D6
11,0 11,5 12,0 12,5 13,0 13,5-1000
0
1000
2000
3000
4000
5000
6000
7000
8000Io
n S
igna
l (ar
b. u
nits
)
Electron energy (eV)
C2D
6
+ / C2D
6
11.46 eV
Izotopic effects in C2D6
aE. Vaseková, M. Stano, S. Matejcik, , J.D. Skalný, P. Mach, T.D. Märk, J. UrbanInt. J. of Mass Spect., 235 (2004) 155-162
e + C2D6 → AE (in eV)
Present Ethana
( C2D6 )+ 11.80 ± 0.05 11.46 ± 0.06
( C2D5 )+ 11.78 ± 0.07 ? 12.06± 0.03
( C2D4)+ 12.09 ± 0.08 11.9± 0.04
( C2D2)+ 15.06± 0.2 15.02± 0.2
Grill et al. ZPhysD 25 (1993) 217
EII to C3H8
10 11 12 13
0
2x10-19
4x10-19
6x10-19
8x10-19
Ion
yie
ld (
arb
. Un
its)
E (eV)
C2H
+ 5/C
3H
8
C3H
+ 8/C
3H
8
C2H
+ 4/C3H
8
C3H
+ 7/C
3H
8
Appearance energies C3H8
Denifl CPL 402 (2005) 80
EII to C3H8 cross sections
Exp: N. Duric, I. Čadež, M. Kurepa, Int. J. Mass Spectrom. & Ion Processes, 108 (1991) R1-R10.
9,5 10,0 10,5 11,0 11,5 12,0 12,5 13,0 13,5 14,0
0,0
2,0x10-17
4,0x10-17
6,0x10-17
C2H
+
5/C
3H
8
C3H+
7/C
3H
8
C2H+
4/C
3H
8
C3H
+
8/C
3H
8
Cro
ss S
ect
ion
[cm
2 ]
Electron Energy [eV]
Total cross sections
σBEB(12 eV) σPresent(12 eV) σExp(12 eV)
[10-16 cm2]
0.119 0.21 0.35
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 BexHy
Experimental problems
Vaporisation only at T>1000°C
Toxicity of Be
BeH dissoc. energy
Roo
sAT
Z
Best Theor.
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6D
e [e
V]
MP2(FC) MP2(Full)
CCSD(t,FC) CCSD(t,Full)
cc-pvXZ aug-cc-pvXZ cc-pCvXZ aug-cc-pCvXZ
CCSDT-R12
1exc. energy 2Σ – 2Π, experiment 17086 cm-1 , theory – 17116 cm-1
BeH bond lenght
X=3
X=2
X=3
X=4
X=5
Roo
sAT
Z
X=5X=4
X=3
X=2
X=2
X=5
X=4
X=5
X=4
X=3
X=2
R12-CCSD(T)
1.310
1.315
1.320
1.325
1.330
1.335
1.340
1.345
1.350
1.355
1.360
Be-
H [
A]
MP2(FC)
MP2(Full)
CCSD(t,FC)CCSD(t,Full)
aug-cc-pCvXZcc-pCvXZaug-cc-pvXZcc-pvXZ
BeH2
basis BeH2
Be-H [A]
TAEa)
[eV]DEBe+H2 [eV]
CCSD(T)-R12
Be:19s14p8d6f4gH: 9s,6p,4d,3f
1.3260 6.418 1.671
CCSD(T) Full
aug-cc-pCvDZ 1.3366 6.108 1.585
aug-cc-pCvTZ 1.3298 6.321 1.614
aug-cc-pCvQZ 1.3267 6.391 1.657
aug-cc-pCv5Z 1.3263 6.406 1.664
B3LYP6-311++G(3d,3p) 1.3248 6.741 1.965
aug-cc-pCv5Z 1.3239 6.748 1.964
BeH2 bond lenght
R12-CCSD(T)
1.315
1.320
1.325
1.330
1.335
1.340
1.345
Be-
H [
A]
MP2(FC)
MP2(Full)
CCSD(t,FC)
CCSD(t,Full)
aug-cc-pvXZ aug-cc-pCvXZcc-pvXZ cc-pCvXZ
BenH clusters – MP2
BenH1
0
2
4
6
8
10
12
1 2 3 4 5
Number of Beryllium Atoms
En
erg
y [e
V]
Energy Difference
Atomization Energy
Be3Hn
Be4Hn
Be4Hn
0
5
10
15
20
25
30
35
0 1 2 3 4 5 6 7 8 9
Number of Hydrogen Atoms
En
erg
y D
iffe
ren
ce
[e
V]
Energy Difference
Atomization Energy
Futher plans
Propane cross section at high T C2D6 – 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
Thank you for your attention