FundingOTKA T 049338Alexander von

Humboldt Foundation

References

[1]: F. Borondics, E. Jakab, S. Pekker: Journal of Nanoscience and Nanotechnology 7, 1551 (2007)[2]: H. Kataura, Y. Kumazawa, Y. Maniwa, I. Umezu, S. Suzuki, Y. Ohtsuka, Y. Achiba: Synth. Metals 103, 2555 (1999)[3]: C. Fantini, M. L. Usrey, M. S. Strano: J. Phys. Chem. C 111, 17941 (2007)[4]: Á. Pekker, D. Wunderlich, K. Kamarás, A. Hirsch: Phys. Stat. Sol. B 245, 1954 (2008)[5]: K. Németh, F. Borondics, E. Jakab, Á. Pekker, K. Kamarás, S. Pekker: Poster #5 on SIWAN 2008[6]: M. Müller, J. Maultzsch, D. Wunderlich, A. Hirsch, C. Thomsen: Phys. Stat. Sol. B 244, 4056 (2007)[7]: K. Kamarás, Á. Pekker: Handbook of Nanoscience and Technology, Editors: A. V. Narlikar, Y. Y. Fu, Oxford University Press, 2009[8]: M. S. Strano: J. Am. Chem. Soc. 125, 16148 (2003)[9]: S. Kazaoui, N. Minami, R. Jacquemin, H. Kataura, Y. Achiba: Phys. Rev. B 69, 13339 (1999)

Most of the functionalization reactions are primarily selective to metallic tubes [7], as these tubes have the nonzero DOS at the Fermi level [8].Birch-type alkylation begins with doping by excess Li, which fills both S11, S22 and M11[9]. The selectivity for metallic tubes is masked

The charged nanotubes are dispersed in the liquid NH3 solution. The size of the cavity in the bundle does not play a role.

Carbanions having greater s-character are more stable. Smaller diameter tubes are more reactive

Selectivity on tube diameter

0 2 4 6 80.2

0.3

0.4

0.5

0.6

0.7

0.8

I(sm

all d

RB

M)

/ I(s

um R

BM

)

(R+H)/100C

According to the RBM spectrum the small diameter semiconducting nanotubes react more readily.This is in accordance with NIR[4, 5] and Raman[6] spectroscopic measurements on alkylated HiPCO tubes. In the case of 531 nm and 676 nm laser excitation the change was obscured by the error.

Explanation of the selectivity

150 200 250

40

60

80

150 200 250

Raman shift (cm-1)

I (ar

b. u

.)

SWNTMe-,H-SWNT 468 nm

S33+S44

S33

M11

The samples

Tubes@Rice:Pulsed laser vaporization SWCNT + Ni/Co catalyst Refluxing with HNO3 SWCNT-COOH Heating to 800 ºC SWCNT

Functionalization by modified Birch reduction [1]:Li + n NH3 Li+ + e- (NH3)n

e- (NH3)n + C C- + nNH3

C- + BzBr BzC + Br-

C- + BuI BuC + I- C- + MeI MeC + I-

C- + HX HC + X-

(HX = H2O, NH3, CH3OH)

The degree of functionalization (R+H)/100C was determined from TG-MS.

The samples are inhomogeneous average spectra selected for comparison with TG-MS

Depth sampling

1300 1400 1500 1600 1700

0

70

140

1300 1400 1500 1600 1700

Bz-, H-SWNT531 nm laser

Inte

nsity

(co

unts

/s)

Raman shift (cm-1)

1300 1400 1500 1600 1700

40

80

120

1300 1400 1500 1600 1700

Bu-, H-SWNT531 nm laser

Inte

nsity

(co

unts

/s)

Raman shift (cm-1)

Resonant Raman scattering

[2]

676 nm

531 nm

468 nm

Raman spectra of functionalized carbon nanotubes

G. Klupp, F. Borondics, R. Hackl*, K. Kamarás, E. Jakab**, S. Pekker Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences,

Budapest, Hungary, e-mail: klupp@szfki.hu*Walther Meissner Institute, Bavarian Academy of Sciences and Humanities, Garching, Germany

**Institute of Materials and Environmental Chemistry, Budapest, Hungary

A complete spectrum

No functional groups are visible and nanotubes are still in resonance. Electronic structure is not collapsed due to functionalization.The same degree of functionalization leads to smaller changes in the electronic structure in the case of apolar alkyl groups than in the case of polar substituted phenyl groups [3].

Lorentzian

Gaussian

Selectivity on tube type

ID/IG and ID/ID* increase with the degree of functionalization, as the change of the electronic structure is only minor. The ratio depends on the wavelength of the exciting laser, as in Ref. 3. If we substract the value measured in the pristine sample (arising from the defects of the pristine nanotube) the change is similar for both metallic and semiconducting nanotubes. The reaction is not selective for tube type

0 2 4 6 80.00

0.01

0.02

0.03

0.04

0.05

I D/I G

- I D

0/I G0

(R+H)/100C

Bz Bu Me

676 nm

531 nm

468 nm

0 2 4 6 8

-0.10

-0.05

0.00

0.05

0.10

0.15

I D/I D

* - I D

0/I D* 0

(R+H)/100C

Bz Bu Me

676 nm

531 nm

468 nm