Europhys. Lett., 57 (5), pp. 677–682 (2002) EUROPHYSICS LETTERS 1 March 2002 Tunable synchrotron radiation used to induce γ -emission from the 31 year isomer of 178 Hf C. B. Collins 1 , N. C. Zoita 1 , A. C. Rusu 1 , M. C. Iosif 1 , D. T. Camase 1 , F. Davanloo 1 , S. Emura 2 , T. Uruga 3 , R. Dussart 4 , J. M. Pouvesle 4 , C. A. Ur 5,6 , I. I. Popescu 6 , V. I. Kirischuk 7 , N. V. Strilchuk 7 and F. J. Agee 8 1 Center for Quantum Electronics, University of Texas at Dallas Richardson, TX 75083-0688, USA 2 The Institute of Scientific and Industrial Research, University of Osaka Osaka 567-0047, Japan 3 SPring-8 / JASRI - Sayo-gun, Hyogo 679-5198, Japan 4 GREMI, CNRS, Universit´ e d’Orl´ eans - Orl´ eans, France 5 H. Hulubei National Institute of Physics and Nuclear Engineering Bucharest, Romania 6 IGE Foundation - Bucharest, Romania 7 Scientific Center ”Institute for Nuclear Research” - Kiev, Ukraine 8 Air Force Office of Scientific Research, AFOSR/NE 801 Randolph St., Arlington, VA 22203-1977, USA (received 28 September 2001; accepted in final form 5 December 2001) PACS. 23.20.Nx – Internal conversion and extranuclear effects. PACS. 25.20.Dc – Photon absorption and scattering. PACS. 27.70.+q – 150 ≤ A ≤ 189. Abstract. – A process for transferring energy from electron shells into nuclear excitation, NEET, has offered the promise for modulating nuclear properties at accessible levels of power. It had been proven recently by exciting a nuclear level of 197 Au with synchrotron radiation, but measured couplings were far below theoretical objectives. Reported here is an extension of that approach for excitation to 178 Hf m2 isomeric nuclei. Isomeric targets were irradiated with X-rays in the beamline BL01B1 at the synchrotron radiation source SPring-8. Energies were tuned from 9 to 13 keV. In this range an excitation branch attributed to NEET was found to have a probability of 2 × 10 -3 relative to L-shell photoionization. The resulting emission of exoergic γ-photons was observed from the target at a rate approaching the theoretical maximum. In 1993, Ho et al. [1] described how higher-order processes for non-resonant excitation (NEET) could couple energy into nuclei from the surrounding electronic shells. “Satellites” on absorption transitions between nuclear levels were predicted. Kishimoto et al. [2] have recently proven such NEET phenomenology by exciting the ground state of 197 Au with synchrotron radiation (SR). They observed the excitation and decay of the (1/2 + → 3/2 + ) (M¨ ossbauer) transition of 197 Au at 77.351 keV by resonant absorption of SR at 80.989 keV. Although the absorption satellite for exciting the nuclear transition was not explored by tuning the SR c  EDP Sciences