Hydrogen Doppler spectroscopy using N-15 ions

The energy spread of atomic and molecular ion beams from the 4 MV Dynamitro n tandem accelerator at the Ruhr-Universitat Bochum has been studied and in part minimized. Using the E-R = 6.40 MeV narrow resonance in H-1(N-15,alph a gamma)C-12 with an N-15 energy spread of 4.55 keV, the Doppler broadening for several hydrogen-bearing gases was found to be in good agreement with expectation: e.g. for NH3 gas a rotational-vibrational Doppler width of 10. 41 +/- 0.25 keV was observed (theory = 10.4 keV). Studies of the vibrationa l Doppler widths of H-bonds on a Si < 100 > surface were performed using a 4 pi gamma-ray detection system together with UHV-chambers for sample prepa ration, transport, and analysis. The results showed that further improvemen ts in the experimental set-ups are needed for such investigations.