Laser-terahertz emission from the chemical sensing plate

Toshihiko Kiwa, Junichi Kondo, Shohei Oka, Iwao Kawayama, Hironobu Yamada, Masayoshi Tonouchi, Keiji Tsukada

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

A new type of sensing system to measure the concentration of the protons in the solutions by means of the laser-terahertz emission and detection was proposed and developed. The simple layered structures of SiO2/Si thin films on a sapphire substrate were prepared as a chemical sensing plate. The system measure the amplitude of the terahertz emission from the depletion layer of SiO2/Si interface by irradiating the femtosecond laser pulses with the center wavelength of 790 nm. The solution was contacted with the SiO 2 surface and the Si thin film layer was electrically grounded. An Ag/AgCl reference electrode was used to control the potential of the solution. When the proton was adsorbed on the surface of the plate, the surface electric dipole was formed at the surface, which changes the local field of the depletion layer. Thus the peak amplitude of terahertz emission was changed depending on the number of the proton adsorbed on the surface of the plate. Actually, we demonstrated that the peak amplitude of terahertz emission from the sensing plate increased by increasing the pH values of the test solution when the bias voltage of the solution was 0 V. (pH values indicate the concentration of the proton in the solution) and the sensitivity was about 31 μV/pH.

Original languageEnglish
Title of host publicationIRMMW-THz2007 - Conference Digest of the Joint 32nd International Conference on Infrared and Millimetre Waves, and 15th International Conference on Terahertz Electronics
Pages285-286
Number of pages2
Publication statusPublished - Dec 1 2007
EventJoint 32nd International Conference on Infrared and Millimetre Waves, and 15th International Conference on Terahertz Electronics, IRMMW-THz2007 - Cardiff, United Kingdom
Duration: Sep 3 2007Sep 7 2007

Publication series

NameIRMMW-THz2007 - Conference Digest of the Joint 32nd International Conference on Infrared and Millimetre Waves, and 15th International Conference on Terahertz Electronics

Other

OtherJoint 32nd International Conference on Infrared and Millimetre Waves, and 15th International Conference on Terahertz Electronics, IRMMW-THz2007
CountryUnited Kingdom
CityCardiff
Period9/3/079/7/07

Keywords

  • Chemical transducers
  • Submillimeter wave measurements
  • Terahertz
  • Ultrafast optics

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Electrical and Electronic Engineering

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  • Cite this

    Kiwa, T., Kondo, J., Oka, S., Kawayama, I., Yamada, H., Tonouchi, M., & Tsukada, K. (2007). Laser-terahertz emission from the chemical sensing plate. In IRMMW-THz2007 - Conference Digest of the Joint 32nd International Conference on Infrared and Millimetre Waves, and 15th International Conference on Terahertz Electronics (pp. 285-286). [4516500] (IRMMW-THz2007 - Conference Digest of the Joint 32nd International Conference on Infrared and Millimetre Waves, and 15th International Conference on Terahertz Electronics).