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研究目的

Research Center for Advanced Laser Spectroscopy and Nanoscience is one of the highlighted Research Centers to advance new science and technology, which are authorized by YNU. The aim of this research center is to develop new laser spectroscopic techniques applicable to nano- and materials sciences. The techniques contain

Recent topics / What's new

  • We have demonstrated that single-cycle THz fields provide control over electrons in a scanning tunneling microscope (STM) with a single tunnel junction. For more detail, see Nature Photonics 10, 796 (2016). (DOI: 10.1038/nphoton.2016.205)

  • We have demonstrated novel single-shot high-repetition-rate measurements of ultrafast and terahertz waveforms by only using a long optical fiber, a single photodiode, and an oscilloscope. For more information, see Scientific Reports. 6, 37614 (2016). (DOI: 10.1038/srep37614)

  • We have demonstrated accurate observations of THz dielectric response due to photoexcited carriers in via single-shot optical-pump and THz-probe spectroscopy. For more information, see Appl. Phys. Lett. 107, 171104: pp. 1-4 (2015). (DOI: http://dx.doi.org/10.1063/1.4934697)

  • We have demonstrated that an intense THz electric field transient accelerates the massive Dirac-like fermions in Bi from classical Newtonian to the relativistic regime; the electrons are accelerated approaching the effective "speed of light" with the "relativistic" beta β = 0.89 along the asymptotic linear band structure. For more information, see Scientific Reports. 5, 15870 (2015). (DOI: 10.1038/srep15870)

  • We have demonstrated real-time observation of phonon-polariton propagation in ferroelectric LiNbO3 using a single-shot spectroscopy with an echelon mirror. For more information, see Appl. Phys. Lett. 107, 062901: pp. 1-5 (2015). (http://dx.doi.org/10.1063/1.4928480)

  • We have demonstrated non-thermal amorphization dynamics of phase-change chalcogenide alloys via ultrafast electron diffraction as well as single-shot pump-probe technique. For more information, see Scientific Reports 5, 13530: pp. 1-9 (2015). (DOI: 10.1038/srep13530)

  • Our review article, describing a description on single-shot imaging spectroscopy using a reflective echelon mirror, has been published in Rev. Laser Eng. 43, pp. 208-212 (2015) (in Japanese).

  • Nonlinear response of localized electrons driven by intense THz electric field transients has been demonstrated in ultrathin Au films with percolated Au nanostructures. *For more information, see Nano Letters 15, pp. 1036-1040 (2015). (DOI: 10.1021/nl503916t)

  • High-frequency coherent phonons resonantly excited in metallic single-walled CNT are examined via spectrally resolved pump-probe spectroscopy. *For more information, see Phys. Rev. B 90, 235435 (2014). (DOI: 10.1103/PhysRevB.90.235435)

  • Linear and nonlinear electron dynamics of polycrystalline Au thin films are revealed via transmittance THz spectroscopy with intense electric field transients. *For more information, see Appl. Phys. Lett. 105, 241107 (2014). (http://dx.doi.org/10.1063/1.4904883)

  • Coherent phonon and surface-enhanced Raman scattering dynamics in solids are reviewed in one of our recent papers. Those include vibrational spectroscopy on graphite-Au nanostructure composite and benzenethiol monolayer film on Au. *For more information, see J. Lumin., 152, pp. 23-27 (2014). (DOI: 10.1016/j.jlumin.2014.01.058)

  • Ultrafast crystalline-to-amorphous phase transition in phase-change chalcogenide alloys has been revealed using broadband single-shot imaging spectroscopy. *For more information, see Appl. Phys. Lett. 104, 261903, 2014 (http://dx.doi.org/10.1063/1.4886969).

  • Ultra-broadband IR and THz generation and detection with ultrashort pulses are approaching the telecommunication frequency of 200 THz has been demonstrated under collaboration with prof. Ashida's group in Osaka University. *see, Proc. SPIE 8964, 896409(1-15), 2014 (doi:10.1117/12.2042829).

  • Broadband pump-probe imaging spectroscopy applicable to ultrafast single-shot events has been developed. Using this new methodology, we present time-frequency 2D images of the transient absorption of photosynthesis organic materials, beta-carotene. *see, Appl. Phys. Exp. 7, 022402, 2014 (doi:10.7567/APEX.7.022402).

  • Intermolecular vibrations relevant to optically and thermally induced magnetic phase transitions in the strongly correlated organic radical TTTA have been revealed using THz time-domain spectroscopy. *see, J. Phys. Soc. Jpn. 83, 014713: pp. 1-6, 2014 (doi: 10.7566/JPSJ.83.014713)

  • Congratulations! Prof. Katayama has been received Young Scientist Award of the Physical Society of Japan in 2014. Please *see http://www.jps.or.jp/activities/awards/jusyosya/wakate2014.html

  • Coherent nanoscale optical-phonon wavepacket in graphene layers has been observed for the first time.* see Phys. Rev. B, 88, 245406: pp. 1-5 (2013). For more details, *see http://journals.aps.org/prb/abstract/10.1103/PhysRevB.88.245406

  • Electronic excited states in strongly correlated organic radical TTTA adsorbed on Si(001) surface have been revealed by means of precise two-photon emission spectroscopy. For more details,* see Phys. Chem. Chem. Phys., 15, 19213 (2013) or *see http://dx.doi.org/10.1039/C3CP52919C

  • Single-shot measurements of terahertz (THz) electric-field waveforms are demonstrated using a reflective echelon mirror, which produces multiple probe pulses with different time-delays. For more information, see Appl. Phys. Lett. 103 051103 (2013), or *see http://dx.doi.org/10.1063/1.4817011.

  • We have demonstrated that a photoconductive antenna gated with 5-fs ultrashort laser pulses can detect electric field transients of near-infrared pulses up to 180 THz.For more information, see Opt. Exp. 21, 16248 (2013) or *see http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-21-14-16248. (IF=3.546)

  • We presented the two invited talks about "surface-enhanced Raman scattering dynamics of solids" at 8th Conference on Ultrafast Surface Dynamics (May 28-31 2013, Colorado, USA) and at 18th Internal Conference on Dynamical Processes in Excited States of Solids (August 4-9 2013, Fuzhou, China).

  • Dynamics of coherent G-mode and D-mode phonons in Ar+-ion implanted graphite has been revealed using transient reflectivity measurement. *see J. Ceramic Society of Japan, 121, 291, 2013.

  • Our invited paper about single-shot imaging spectroscopy is issued in The Review of Laser Engineering (in Japanese). *see The Review of Laser Engineering, 40, 598, 2012.

  • The dynamics of photoluminescence due to biexcitons and exciton-exciton scattering has been revealed in the layered-type semiconductor PbI2 by using the optical Kerr gate method.
    *see http://dx.doi.org/10.1103/PhysRevB.86.155206

  • Surface metallic state in single crystalline ultrathin Bi(001) films on Si(111) 7x7 surface has been clarified with terahertz time-domain spectroscopy. (Y. Yokota et al., Appl. Phys. Lett., 100, 251605, 2012)
    *see http://dx.doi.org/10.1063/1.4729149

  • Using an electro-optic sampling method, the electric field of coherent synchrotron radiation (CSR) generated by laser bunch slicing in a storage ring has been successfully detected. (I. Katayama et al., Appl. Phys. Lett., 100, 111112, 2012)
    *see http://dx.doi.org/10.1063/1.3694049

  • Using intense picosecond THz pulses, we could successfully drive the ferroelectric soft mode in SrTiO3 thin films to the anharmonic region with large amplitude. This research result will appear in Physical Review Letters (APS journal) with a high impact factor. (I. Katayama et al., Phys. Rev. Lett. 108, 097401, 2012.)
    *see http://link.aps.org/doi/10.1103/PhysRevLett.108.097401

  • Using an echelon mirror having a micro-step structure, we have successfully demonstrated single-shot time-frequency imaging spectroscopy for measuring ultrashort laser pulses as well as ultrafast responses of materials. This result will be published in Optics Letters (OSA journal) with a high impact factor. A part of the results for the single-shot imaging spectroscopy was also published in JJAP.(H. Sakaibara et al., Opt. Lett. 37, pp. 1118-1120 (2012); I. Katayama et al., Jpn. J. Appl. Phys. 50, 102701, 2011)
    *see http://jjap.jsap.jp/spotlights/index.html

  • We have demonstrated ultrafast dynamics of surface-enhanced Raman scattering (SERS) at cleaved graphite surfaces bearing deposited Au nanostructures using sensitive pump-probe reflectivity spectroscopy with ultrashort (7.5 fs) laser pulses. The result appeared in Nano Letters (ACS journal) with a high impact factor.(I. Katayama et al., Nano Letters, 11, 2648, 2011)
    *see http://pubs.acs.org/doi/abs/10.1021/nl200667t#citing

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