Transcript Slide 1
Nano-spectroscopy of Individual Single Walled Carbon Nanotubes 1um AFM image • 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 incoming Lattice vibrations Stokes scattered outgoing Eii laser Energy and momentum conservation: L S phonon Anti- Stokes KL KS qphonon incoming Stokes Anti-Stokes -300 -200 -100 0 100 200 300 -1 Raman shift (cm ) BOSTON UNIVERSITY PHYSICS DEPARTMENT Raman Intensity Antistokes Eii Eii Stokes outgoing ERBM Elaser Resonant Raman Scattering from a single CNT AS RBM -258 cm-1 One nanotube, resonant with BOTH incoming and outgoing laser BOSTON UNIVERSITY PHYSICS DEPARTMENT 1 µm trench Stokes RBM 258 cm-1 Raman map of Radial Breathing Mode Raman intensity enhancement over trench AFM Induced Strain • Tubes are strained by pushing with AFM tip • Raman spectra measured before and after strain Cronin, et. al, PRL, 93 (2004) BOSTON UNIVERSITY PHYSICS DEPARTMENT Laser spot Metal Pads Comparison of Confocal to Tip-Enhanced in Raman Microscopy of Carbon Nanotubes Confocal image BOSTON UNIVERSITY PHYSICS DEPARTMENT Tip-enahnced image of same area