Dwyer C1, Aoki T2, Rez P1, Chang SL2, Lovejoy TC3, Krivanek OL1,3.
Phys Rev Lett. 2016 Dec 16;117(25):256101. doi: 10.1103/PhysRevLett.117.256101. Epub 2016 Dec 15.We demonstrate that a focused beam of high-energy electrons can be used to map the vibrational modes of a material with a spatial resolution of the order of one nanometer. Our demonstration is performed on boron nitride, a polar dielectric which gives rise to both localized and delocalized electron-vibrational scattering, either of which can be selected in our off-axial experimental geometry. Our experimental results are well supported by our calculations, and should reconcile current controversy regarding the spatial resolution achievable in vibrational mapping with focused electron beams.