SZÉN NANOCSÖVEK RAMAN -SPEKTROSZKÓPIÁJA (kis bevezetéssel)

1. SZÉN NANOCSÖVEK RAMAN-SPEKTROSZKÓPIÁJA(kis bevezetéssel) NANOSZEMINÁRIUM 2010. Mikulás Kürti Jenő ELTE Biológiai Fizika Tanszék e-mail: kurti@virag.elte.hu www: virag.elte.hu/~kurti

2. VÁZLAT • Bevezetés a Raman spektroszkópiáról • Lélegző módus (RBM) szén nanocsövekben • D (és D* = G´= 2D) sáv grafitban (grafénban) • D (és D* = G´= 2D) sáv szén nanocsövekben

3. Sir Chandrasekhara Venkata Raman (7 November 1888 – 21 November 1970) The Nobel Prize in Physics 1930 "for his work on the scattering of light and for the discovery of the effect named after him".

9. anti - Stokes Stokes

14. Tipikus infravörös és Raman-spektrum B. Schrader: Raman/Infrared Atlas of OrganicCompounds. VCH Publishers, 1989.

17. g = 120

21. Egyfalú szén nanocsövek keverékének Raman-spektruma (D* band)

22. 1

23. Radial Breathing Modeincarbon nanotubes

24. D band Radial Breathing Mode

26. RBM0 DFT (5,3) quadratic fit force constant RBM-frequency

27. RBM vs 1/d0 linear fit for large diameters Alarge_d= 233.1 ZZ AC CH n (cm-1) 1/d0 (nm-1) J.Kürti et al, NJP 5, art. no.-125, (2003)

28. RBM vs 1/ddeviation from linear fit 5,3 7,0 ZZ AC CH Dn (cm-1) d=0.5546 nm 1/d (nm-1)

29. Raman Stokes: w2=w1 – w (Anti-Stokes: w2=w1+w) b a 0 w, 0 w, w, w1 w w1 w2=w1 –w w1 w2=w1 +w w w1

30. hin hout hin hout hin hout (incoming) resonance Raman

31. (6,5) - DFT

32. 2D RBM Two-dimensional plot of the radial-breathing-mode range vs. laser excitation energy. Note the various laola-like resonance enhancements, from which we can determine both the optical transition energies and the approximate diameter of the nanotubes. The spectra were each calibrated against the Raman spectrum of CCl4.

33. Contour plot of 2D RBM 2n+m = constant „families”

36. AAC= 236 AZZ= 232 ZZ AC CH

37. COUPLING of TOTALLY SYMMETRIC MODES (RBM + G (HFM)) radial tangential 1 for achiral 2 for chiral

38. ZZ AC CH

39. Kataura plot 11 22 11

40. Lines of allowed k vectors for the three nanotube families on a contour plot of the electronic band structure of graphene (Kpoint at center). (a) metallic nanotube belonging to the ν = 0 family (b) semiconducting −1 family tube (c) semiconducting +1 family tube

41. (a) Kataura plot: transition energies of semiconducting (filled symbols) and metallic (open) nanotubes as a function of tube diameter. (Calculated from the Van-Hove singularities in the joint density of states within the third-order tight-binding approximation.) (b) Expanded view of the Kataura plot highlighting the systematics in (a). The optical transition energies follow roughly 1/d for semiconducting (black) and metallic nanotubes (grey). The V-shaped curves connect points from selected branches (2n+m = 22, 23 and 24). For each nanotube subband transition Eiiit is indicated whether the ν = −1 or the +1 family is below or above the 1/d average trend. Squares (circles) are zigzag (armchair) nanotubes.

42. Kísérleti Kataura-plot

43. Spectrofluorimetric measurements, Science 298, 2361 (2002) Cross-section model of a SWCNT in a cylindrical SDS micelle SDS: sodium dodecyl sulfate (SDS) surfactant.

44. Spectrofluorimetric measurements, Science 298, 2361 (2002) (A) Contour plot of fluorescence intensity versus excitationand emission wavelengths for a sample of SWNTs suspended in SDSand deuterium oxide. (B) Circles show spectral peak positions from (A); linesshow perceived patterns in the data.

45. Szén nanocsövek válogatása lehetséges (Hersam, Kataura) Fémes vagy félvezető, illetve átmérők szerint (Arnold et al, Nature Nanotech. 2006: density gradient ultracentrifugation, 270000 g)

46. Fluorescence: high selectivity