Quantifying electron-phonon interactions for the surface states of
topological materials can provide key insights into surface-state transport,
topological superconductivity, and potentially how to manipulate the surface
state using a structural degree of freedom. We perform time-resolved x-ray
diffraction (XRD) and angle-resolved photoemission (ARPES) measurements on
Bi2Te3 and Bi2Se3, following the excitation of coherent A1g
optical phonons. We extract and compare the deformation potentials coupling the
surface electronic states to local A1g-like displacements in these two
materials using the experimentally determined atomic displacements from XRD and
electron band shifts from ARPES.We find the coupling in Bi2Te3 and
Bi2Se3 to be similar and in general in agreement with expectations from
density functional theory. We establish a methodology that quantifies the
mode-specific electron-phonon coupling experimentally, allowing detailed
comparison to theory. Our results shed light on fundamental processes in
topological insulators involving electron-phonon coupling