Details of coherent phonon motion in tellurium

We study impulsively excited coherent phonons in tellurium at various lattice temperatures and excitation densities. From a comparison with temperature-dependent reflectivity and X-ray scattering data, we infer the direction and estimate the amplitude of the coherent ionic motion. In addition, we show quantitatively that electronic weakening of the crystal forms the dominant contribution to a density-dependent red-shift of the phonon frequency.