About the Cover

Vol. 85 No. 10 (2009)

  In 1963 Jun-ichi Nishizawa predicted coherent terahertz electromagnetic wave generation via the resonance of phonons and molecular vibrations. In 1980 Nishizawa and Suto, following this proposal, developed and realized a semiconductor Raman laser using a GaP crystal, from which a terahertz (THz) wave was actually generated. Recently, they constructed a THz generator with automatic scanning control, which made it possible to measure spectral shapes of various organic molecules in a very wide frequency range (0.8 – 5.4 THz). The illustration shows absorption spectra of five nucleobases which constitute DNA and RNA. Marked differences are revealed among these molecules in the wide frequency range. Taken from a review article of J. Nishizawa in this issue pp. 454-465.