eels analysis of carbon structures nanotube seminar 2005. 05. 09. gergely kovách mta mfa
TRANSCRIPT
EELS analysis of carbon structures
Nanotube seminar2005. 05. 09.
Gergely KováchMTA MFA
Electron spectroscopy
-EELS, electron energy loss is characteristical to the material-XPS, binding energy of C1s (284.6eV, 285.4eV) core level electron, energy loss of core level electron
Electron energy loss in solids
a – zero loss
b – fonons
c – band transitions
d – surface plasmons
e – bulk plasmons
f – inner shell absorption edge
Hybridization of C atoms
-Energy difference in hybridized orbitals
-Broadening of bonds
-Also valid for amorphous structure
-Pre edge feature in C1s-2p absorption 1s-2p(*)
Core level absorption spectra of C samples
DLC
Graphite
Evap. C
J. Yuan, Micron 515 (2000)
STEM at 100 kV
sp2/sp3 obtained from peak intensity
Polarization of 1s-2pz transition
Anisotropic response of 1s-2p dipole transition -> difficulties in quantitative analysis
sp2/sp3 ratio:Plasmon energy shift
sp2/sp3 ratio:using reference material
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 5 10 15 20 25 30 35 40 45 50 55 60
energy loss [eV]
no
rmal
ized
in
ten
sity
[cp
s]
(c) Ar bomb.
(b) He bomb.
Polycristallinediamond
(a)
sp2/sp3 ratio:C1s binding energy
Own measurementsEELS of 500eV electrons
0
1000
2000
3000
4000
5000
6000
7000
0 10 20 30 40 50 60
Energy loss [eV]
inte
nsity
[arb
. uni
t]
Nanotube
HOPG
HOPG impl.
References
• J. Robertson, Mat. Sci. and Eng. R 37 (2002) 129-281• P. J. Fallon, V. S. Veerasamy, C. A. Davis, J. Robertson, G. A. J. Amaratunga, W. I.
Milne, J. Koskinen Phys. Rev. B 48, 4777–4782 (1993) Phys. Rev. B 48, 4777 (1993)
• R.F.Egerton, Electron Energy-Loss Spectroscopy in the Electron Microscope (1986)• J. Bruley, L.M. Brown and S.D. Berger. Inst. Phys. Conf. Ser. 78 (1985), p. 561.• S. D. Berger, D. R. McKenzie, and P. J. Martin, Philos. Mag. Lett. 57, 285 (1988) [
CAS][INSPEC].• J. Kulik et. al. Phys. Rev. B Vol. 52, No. 22. 15812 (1995)• J. Yuan, L.M. Brown, Micron 31 (2000) 515• G. Kovach, H. Csorbai, G.Z. Radnoczi, et al., Mat. Sci. Forum 414-4: 127-132, 2003
Properties of high-density amorphous carbon films deposited by laser ablation • S. Rey et. al. Appl. Phys. A 71 433 (2000)• [14] Y. Lifshitz, Diam. Rel. Mat. 8, 1659 (1999) Phys. Rev. B 48, 4777–4782 (1993)
http://prola.aps.org/abstract/PRB/v48/i7/p4777_1• D. L. Pappas, K. L. Saenger, J. Bruley, W. Krakow and J. J. Cuomo, J. Appl. Phys. 71
, 5675 (1992) [ADS][ SPIN][ INSPEC];• J. J. Cuomo et al., Appl. Phys. Lett. 58, 466 (1991) [ADS][CAS][ SPIN][ INSPEC].• J. Kulik et al., J. Appl. Phys. 76, 5063 (1994) [ADS][CAS][ SPIN][INSPEC].