We report the nanometer scale mapping of a single Ge nanowire (NW) using tip-enhanced Raman scattering (TERS). The Raman spectra of a single Ge NW show downshift and asymmetric broadening, depending on the diameter, due to the phonon confinement effect. A Raman peak attributed to amorphous Ge has also been observed. Assuming the crystalline core/amorphous shell structure, we estimate the amorphous shell thickness to be 2–6 monolayers from the integrated Raman intensities of crystalline and amorphous Ge.
Molecular vibration of several modes in blue-phase polydiacetylene-3-butoxycarbonylmethylurethane (PDA-3BCMU) was real-time observed by 5-fs pump-probe measurement. The contribution of the vibrational wave packets in the ground state and in the excited state in the signal were separated by multichannel measurement. The C v C stretching mode in the ground state starts to oscillate -out-of-phase with the C w C stretching mode. The structure of PDA-3BCMU in the geometrically relaxed state is not pure butatriene type but more like acetylene type. The frequencies of C v C and C w C stretching modes there were determined by singular value decomposition method to be 1472± 6 cm −1 and 2092± 6 cm −1 , respectively. The double and triple bond stretching frequencies in the ground state are 1463± 6 cm −1 and 2083± 6 cm −1 , respectively.
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