Elementary Excitations in a Carbon Nanotube

概要

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A carbon nanottrbe exhibits the decoupled rc Pl21SlIl0IlS of difl'erent angtrlar mornenta (L's).The magnetic fltrx is expected to be ttseftrl in identifying thena. All the L-decoupled Pl2lSIl1Ol1Shave strong dispersion relations with naouaaenttttn (q). The L / O plasrnons belong to opticalplasmons, while the L : O plasmon cotrld not exist at q -* O. The f'ornner, respectively, behave asthe plasmons in three- and two-dimensional electron gases at srnall and large q's. The plasmonfrequencies would be affected by radius, chiral angle, and interttrbe inter'action. To obtainthe actual plasmon frequencies of a multi-shell nanottrbe, the interttrbe interactions frona theneighboring shells have to be taken into accotrnt. The calcvrl?tted results are consistent wmth theexperimental measurennents. A detailed counparisorr between a carbon nanotube and a grapluitelayer is also made. These txvo related systems znay exhiTcit sitnilar 7T plasrnorrs, when L : O iraa nanottmbe. Furtlaerrnore, the chirality effect of the ['ormer cor'r'esponds to the anisotropy effectof the latter. The predicted q-, L-, and geotnetry-dependence of' the 'x plasmons needs f'urtherexperimental verifications.
1997-03-15