BOSTON UNIVERSITY PHYSICS DEPARTMENT

Nano-spectroscopy of Individual Single Walled Carbon Nanotubes

AFM image

1um

• Measure single, unperturbed nanotube• Determine fundamental optical property• Excitonic versus van Hove singularity• Contact to measure strain, conductivity

BOSTON UNIVERSITY PHYSICS DEPARTMENT

Resonant Raman Scattering from a single CNT

laser

scattered

-300 -200 -100 0 100 200 300

Raman shift (cm-1

)

StokesAnti-Stokes

phonon

phonon

L S

L S

K K q

Energy and momentum conservation:

Lattice vibrations

ERBM

outgoing

incoming Eii

Stokes

Elaser

RamanIntensity

Anti-stokes

incoming outgoing

StokesEii

Anti- StokesEii

BOSTON UNIVERSITY PHYSICS DEPARTMENT

Resonant Raman Scattering from a single CNT

Stokes RBM 258 cm-1AS RBM -258 cm-1

Raman intensity enhancement over trench

1 µmtrench

Raman map of Radial Breathing Mode

One nanotube, resonant with BOTH incoming and outgoing laser

BOSTON UNIVERSITY PHYSICS DEPARTMENT

AFM Induced Strain

• Tubes are strained by pushing with AFM tip

• Raman spectra measured before and after strain

3

m

m

before

after

AFM tip

Metal Pads

Laser spot

Cronin, et. al, PRL, 93 (2004)

BOSTON UNIVERSITY PHYSICS DEPARTMENT

Comparison of Confocal to Tip-Enhanced in Raman Microscopy of Carbon Nanotubes

Confocal imageTip-enahnced image of same area