Surface-enhanced infrared spectroscopy using nanometer-sized gaps.
We report on the near-field coupling of individual gold nanoantennas arranged in tip-to-tip dimer configuration, leading to strong electromagnetic field enhancements in the infrared, which is of great interest for sensing applications such as surface-enhanced infrared spectroscopy. We quantitatively evaluated the enhancement of vibrational excitations of a 5 nm thick test layer of 4,4'-bis(N-carbazolyl)-1,1'-biphenyl as a function of different gap sizes. The dimers with the smallest gaps under investigation (∼3 nm) lead to more than 1 order of magnitude higher signal enhancement with respect to gaps of 50 nm width. The comparison of experimental data and finite-difference time-domain simulations reveals a nonperfect filling of the gaps with sizes below 10 nm, which means that morphological information on the nanoscale is obtained additionally to chemical information.
Kirchhoff Institute for Physics, University of Heidelberg , Im Neuenheimer Feld 227, 69120 Heidelberg, Germany.
Christian
C
Huck
Frank
F
Neubrech
Jochen
J
Vogt
Andrea
A
Toma
David
D
Gerbert
Julia
J
Katzmann
Thomas
T
Härtling
Annemarie
A
Pucci