  Understanding exotic solids is a difficult task as interactions are often
hidden by the symmetry of the system. Here, we study the electronic properties
of a noncentrosymmetric solid, BiPd, which is a rare material exhibiting both
superconductivity and topological phase of matter. Employing high resolution
photoemission spectroscopy with photon energies ranging from hard x-ray to
extreme ultraviolet regime, we show that hard x-ray spectroscopy alone is not
enough to reveal surface-bulk differences in the electronic structure. We
derived the escape depths close to the extreme surface sensitivity and find
that the photon energies used for high resolution measurements such as ARPES
fall in the surface sensitive regime. In addition, we discover deviation of the
branching ratio of Bi core level features derived from conventional quantum
theories of the core hole final states. Such paradigm shift in core level
spectroscopy can be attributed to the absence of center of symmetry and
spin-orbit interactions.
