Ultrafast Generation of Fundamental and Multiple-Order Phonon Excitations in Highly Enriched (6,5) Single-Wall Carbon Nanotubes

Abstract

Using a macroscopic ensemble of highly-enriched (6,5) single-wall carbon nanotubes, combined with high signal-to-noise ratio, time-dependent differential transmission spectroscopy, we have generated vibrational modes in an ultrawide spectral range (10-3000 cm −1 ). A total of fourteen modes were clearly resolved and identified, including fundamental modes of A, E1, and E2 symmetries and their combinational modes involving two and three phonons. Through comparison with CW Raman spectra as well as calculations based on an extended tight-binding model, we were able to identify all the observed peaks and determine the frequencies of the individual and combined modes. We provide a full summary of phonon frequencies for (6,5) nanotubes that can serve as a basic reference with which to refine our understanding of nanotube phonon spectra as well as a testbed for new theoretical models.

NanoJapan: international research experience for undergraduates program: fostering U.S.-Japan research collaborations in terahertz science and technology of nanostructures

“…Some of the ongoing research projects include active and/or plasmonic THz sources and detectors based on graphene, [8][9][10] development of THz polarizers 11,12 and detectors [13][14][15] based on aligned single-wall carbon nanotubes, ultrafast optical spectroscopy of coherent THz phonons in carbon nanomaterials, [16][17][18] and 3D micro-fabrication of single-wall carbon nanotube/polymer composites by two-photon polymerization lithography. 19 The electromagnetic spectrum from 0.1 to 10 THz offers many opportunities to study physical phenomena, with potential payoff in numerous technologies.…”

Coherent optical phonon oscillation and possible electronic softening in WTe2 crystals

“…Time-resolved study can probe the dynamics of anharmonic phonons due to the electronic softening 37 38 39 with anomaly variations of phonon frequency and phonon spectra under high density photoexcitation, providing key knowledge for light-induced structure modification 32 33 . Time-resolved spectroscopy has been adopted to study the coherent lattice dynamics in 1D 40 41 and 2D materials 42 43 44 45 46 47 , providing key information on the electron/exciton-phonon interaction, the interlayer coupling, and nonlinear lattice dynamics.…”

Origin of coherentG-band phonon spectra in single-wall carbon nanotubes

“…For example, a pump-probe measurement by Lim et al gave the RBM intensity of about eight times larger than the LO intensity. 9 Although this discrepancy is not significant in our present discussion, we expect that it might come from the additional effect of the selection of laser pulse width τ p as we will discuss below.…”

“…8 Lim et al showed that even the low-frequency acoustic phonon signals can be observed in purified (6,5) SWNTs by coherent phonon spectroscopy because of its ultrafine spectral resolution. 9 Moreover, ultrafast spectroscopy techniques allow us to directly measure phonon dynamics, including phase information, or life time of phonons, in the time domain.…”