TY - JOUR
T1 - Phase analysis of coherent radial-breathing-mode phonons in carbon nanotubes
T2 - Implications for generation and detection processes
AU - Shimura, Akihiko
AU - Yanagi, Kazuhiro
AU - Yoshizawa, Masayuki
N1 - Funding Information:
We thank T. Kobayashi and R. Saito for valuable comments. K.Y. acknowledges support by JSPS KAKENHI through Grant No. JP16H00919, and JST CREST Grant No. JPMJCR17I5. M.Y. acknowledges support by JSPS KAKENHI through Grants-in-Aid for Scientific Research on Innovative Areas “Soft Molecular Systems”.
Publisher Copyright:
© 2018 American Physical Society.
PY - 2018/1/30
Y1 - 2018/1/30
N2 - In time-resolved pump-probe spectroscopy of carbon nanotubes, the fundamental understanding of the optical generation and detection processes of radial-breathing-mode (RBM) phonons has been inconsistent among the previous reports. In this study, the tunable-pumping/broadband-probing scheme was used to fully reveal the amplitude and phase of the phonon-modulated signals. We observed that signals detected off resonantly to excitonic transitions are delayed by π/2 radians with respect to resonantly detected signals, which demonstrates that RBM phonons are detected through dynamically modulating the linear response, not through adiabatically modulating the light absorption. Furthermore, we found that the initial phases are independent of the pump detuning across the first (E11) and the second (E22) excitonic resonances, evidencing that the RBM phonons are generated by the displacive excitation rather than stimulated Raman process.
AB - In time-resolved pump-probe spectroscopy of carbon nanotubes, the fundamental understanding of the optical generation and detection processes of radial-breathing-mode (RBM) phonons has been inconsistent among the previous reports. In this study, the tunable-pumping/broadband-probing scheme was used to fully reveal the amplitude and phase of the phonon-modulated signals. We observed that signals detected off resonantly to excitonic transitions are delayed by π/2 radians with respect to resonantly detected signals, which demonstrates that RBM phonons are detected through dynamically modulating the linear response, not through adiabatically modulating the light absorption. Furthermore, we found that the initial phases are independent of the pump detuning across the first (E11) and the second (E22) excitonic resonances, evidencing that the RBM phonons are generated by the displacive excitation rather than stimulated Raman process.
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U2 - 10.1103/PhysRevB.97.035441
DO - 10.1103/PhysRevB.97.035441
M3 - Article
AN - SCOPUS:85042094550
VL - 97
JO - Physical Review B
JF - Physical Review B
SN - 2469-9950
IS - 3
M1 - 035441
ER -