Raman spectrum and lattice parameters of MgB2 as a function of pressure - art. no. 100509

We report Raman spectra and synchrotron x-ray diffraction measurements of l attice parameters of polycrystalline MgB2 under hydrostatic pressure condit ions up to 15 GPa. An anomalously broadened Raman band at 620 cm(-1) is obs erved that exhibits a large linear pressure shift of its frequency. The lar ge mode damping and Gruneisen parameter indicate the vibration is highly an harmonic, broadly consistent with theoretical predictions for the E-2g in-p lane boron stretching mode. The results obtained may provide additional con straints on the electron-phonon coupling in the system.