TY - JOUR
T1 - Excitation of long-wavelength surface optical vibrational modes in films, cubes and film/cube composite system using an atom-sized electron beam
AU - Lagos, Maureen J.
AU - Trügler, Andreas
AU - Amarasinghe, Voshadhi
AU - Feldman, Leonard C.
AU - Hohenester, Ulrich
AU - Batson, Philip E.
N1 - Funding Information:
M.J.L. and P.E.B. acknowledge the financial support of U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award #DE-SC0005132. U.H. and A.T. acknowledge the financial support by the Austrian Science Fund FWF under project P27299-N27 and the SFB F49 NextLite (F4906-N23). U.H. and A. T. also thank G. Unger for helpful discussions regarding BEM eigenmodes. V.P.A. and L.C.F. acknowledge the financial support of the II-VI foundation and the Army Research Laboratory (programme coordinator Dr Aivars J. Lelis).
PY - 2018/3/1
Y1 - 2018/3/1
N2 - Using spatially resolved Electron Energy-Loss Spectroscopy, we investigate the excitation of long-wavelength surface optical vibrational modes in elementary types of nanostructures: an amorphous SiO2 slab, an MgO cube, and in the composite cube/slab system. We find rich sets of optical vibrational modes strongly constrained by the nanoscale size and geometry. For slabs, we find two surface resonances resulting from the excitation of surface phonon polariton modes. For cubes, we obtain three main highly localized corner, edge, and face resonances. The response of those surface phonon resonances can be described in terms of eigenmodes of the cube and we show that the corresponding mode pattern is recovered in the spatially resolved EELS maps. For the composite cube/substrate system we find that interactions between the two basic structures are weak, producing minor spectral shifts and intensity variations (transparency behaviour), particularly for the MgO-derived modes.
AB - Using spatially resolved Electron Energy-Loss Spectroscopy, we investigate the excitation of long-wavelength surface optical vibrational modes in elementary types of nanostructures: an amorphous SiO2 slab, an MgO cube, and in the composite cube/slab system. We find rich sets of optical vibrational modes strongly constrained by the nanoscale size and geometry. For slabs, we find two surface resonances resulting from the excitation of surface phonon polariton modes. For cubes, we obtain three main highly localized corner, edge, and face resonances. The response of those surface phonon resonances can be described in terms of eigenmodes of the cube and we show that the corresponding mode pattern is recovered in the spatially resolved EELS maps. For the composite cube/substrate system we find that interactions between the two basic structures are weak, producing minor spectral shifts and intensity variations (transparency behaviour), particularly for the MgO-derived modes.
KW - Infrared terahertz
KW - Surface optical phonons
KW - Surface phonon polariton
KW - Vibrational EELS
KW - Vibrational scattering cross-section
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U2 - 10.1093/jmicro/dfx130
DO - 10.1093/jmicro/dfx130
M3 - Article
C2 - 29370423
AN - SCOPUS:85044526443
VL - 67
SP - i3-i13
JO - Microscopy (Oxford, England)
JF - Microscopy (Oxford, England)
SN - 2050-5698
ER -