title: Observation of terahertz-radiation-induced ionization in a single nano island.
abstract: Terahertz (THz) electromagnetic wave has been widely used as a spectroscopic probe to detect the collective vibrational mode in vast molecular systems and investigate dielectric properties of various materials. Recent technological advances in generating intense THz radiation and the emergence of THz plasmonics operating with nanoscale structures have opened up new pathways toward THz applications. Here, we present a new opportunity in engineering the state of matter at the atomic scale using THz wave and a metallic nanostructure. We show that a medium strength THz radiation of 22 kV/cm can induce ionization of ambient carbon atoms through interaction with a metallic nanostructure. The prepared structure, made of a nano slot antenna and a nano island located at the center, acts as a nanogap capacitor and enhances the local electric field by two orders of magnitudes thereby causing the ionization of ambient carbon atoms. Ionization and accumulation of carbon atoms are also observed through the change of the resonant condition of the nano slot antenna and the shift of the characteristic mode in the spectrum of the transmitted THz waves.
authors.affiliation: Sensor System Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea.
authors.forename: Minah
authors.initials: M
authors.lastname: Seo
authors.affiliation: Department of Physics, Korea University, Seoul 136-701, Republic of Korea.
authors.forename: Ji-Hun
authors.initials: JH
authors.lastname: Kang
authors.affiliation: Sensor System Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea.
authors.forename: Hyo-Suk
authors.initials: HS
authors.lastname: Kim
authors.affiliation: Sensor System Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea.
authors.forename: Joon
authors.initials: J
authors.lastname: Hyong Cho
authors.affiliation: Sensor System Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea.
authors.forename: Jaebin
authors.initials: J
authors.lastname: Choi
authors.affiliation: Sensor System Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea.
authors.forename: Young
authors.initials: Y
authors.lastname: Min Jhon
authors.affiliation: Sensor System Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea.
authors.forename: Seok
authors.initials: S
authors.lastname: Lee
authors.affiliation: Sensor System Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea.
authors.forename: Jae
authors.initials: J
authors.lastname: Hun Kim
authors.affiliation: Sensor System Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea.
authors.forename: Taikjin
authors.initials: T
authors.lastname: Lee
authors.affiliation: Department of Physics, Korea University, Seoul 136-701, Republic of Korea.
authors.forename: Q-Han
authors.initials: QH
authors.lastname: Park
authors.affiliation: Sensor System Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea.
authors.forename: Chulki
authors.initials: C
authors.lastname: Kim