Major research fields
Solar Energy Conversion, Semiconductor Quantum Dots
Nanosized materials such as semiconductors and noble metals have several unique features such as size-dependent electronic and optical properties different from the bulk, which can be tuned simply by changing their size, shape, or their surface characteristics. These features turn them into promising materials for a number of optical and biological applications as well as solar energy conversion. Colloidal synthesis is a promising method to prepare these nanosized materials.
Professor TAMAI is interested in the optical and dynamical properties of various kinds of semiconductor quantum dots, nanorods, and nanowires as well as plasmonic nanomaterials such as Au and Ag. Various experimental techniques including ultrafast laser spectroscopy and microscopy allow us to examine how the optical and dynamical properties of semiconductor or metal nanoparticles depend on their size and shape. In addition, electron transfer dynamics and mechanisms using semiconductor nanomaterials and plasmonic systems are fundamental importance for solar energy conversion.
He is also focused on graphene, an atomically thin layer of sp2-hybridized carbon that possesses spectacular electronic, optical, magnetic, thermal and mechanical properties, thus making it an exciting material in a variety of important applications. Space-resolved Raman spectroscopy is used to examine the spatial and optical properties of graphene. Ultrafast laser spectroscopy of various nanomaterials on graphene is important for understanding the interaction between nanomaterials and graphene and for realizing nanoelectronics.
Major relevant publications
- Y. Kobayashi, T. Nishimura, H. Yamaguchi, and N. Tamai, Effect of Surface Defects on Auger Recombination in Colloidal CdS Quantum Dots, J. Phys. Chem. Lett., 2, 1051-1055 (2011).
- L. Wang, A. Kiya, Y. Okuno, Y. Niidome, and N. Tamai, Ultrafast Spectroscopy and Coherent Acoustic Phonon of Au-Ag Core-Shell Nanorods, J. Chem. Phys., 134, 054501-1-054501-6 (2011).
- L. Pan, Y. Kobayashi, and N. Tamai, Nonlinear Optical Properties and Single Particle Spectroscopy of CdTe Quantum Dots, in "Molecular Nano Dynamics", Eds. by H. Fukumura, M. Irie, Y. Iwasawa, H. Masuhara, K. Uosaki (Wiley-VCH, 2009), Vol. 1, Chap. 9, pp.155-169.