Chemical sensing plate with a laser-terahertz monitoring system.

A new type of laser-terahertz emission system for noncontact investigations of chemical solutions has been developed. The system monitors terahertz emission from a sensing plate, which consists of silicon oxide and silicon thin film layers on a sapphire substrate. Sensing of chemical solutions with pH values between 1.68 and 10.01 was demonstrated. The amplitude of the terahertz emission from the sensing plate increased with increasing pH value. This change in the amplitude was caused by a change in the depletion layers of the silicon thin film when protons were adsorbed on the surface of the sensing plate. This study demonstrates that full noncontact monitoring of chemical solutions is possible using the laser-terahertz emission system.

[1]  A new pH-ISFET based dissolved oxygen sensor by employing electrolysis of oxygen , 1996 .

[2]  R. Blundell,et al.  A photomixer local oscillator for a 630-GHz heterodyne receiver , 1999, IEEE Microwave and Guided Wave Letters.

[3]  Daniel R. Grischkowsky,et al.  THz time-domain spectroscopy of high Tc substrates , 1990 .

[4]  Edmund H. Linfield,et al.  Applications of terahertz (THz) technology to medical imaging , 1999, Industrial Lasers and Inspection.

[5]  Maya R. Gupta,et al.  Recent advances in terahertz imaging , 1999 .

[6]  Masatsugu Yamashita,et al.  Laser terahertz-emission microscope for inspecting electrical faults in integrated circuits. , 2003 .

[7]  K. Cheung,et al.  Picosecond photoconducting Hertzian dipoles , 1984 .

[8]  K. Cheung,et al.  Coherent time-domain far-infrared spectroscopy , 1985 .

[9]  B. Ferguson,et al.  T-ray computed tomography. , 2002, Optics letters.

[10]  K. Kawase,et al.  Non-destructive terahertz imaging of illicit drugs using spectral fingerprints. , 2003, Optics express.

[11]  Xiang Zhang,et al.  Generation of femtosecond electromagnetic pulses from semiconductor surfaces , 1990 .

[12]  Masayoshi Tonouchi,et al.  Ultrashort Electromagnetic Pulse Radiation from YBCO Thin Films Excited by Femtosecond Optical Pulse , 1996 .

[13]  Masatsugu Yamashita,et al.  Imaging of large-scale integrated circuits using laser-terahertz emission microscopy. , 2005, Optics express.

[14]  M. Tonouchi,et al.  Laser terahertz emission system to investigate hydrogen gas sensors , 2005 .

[15]  M. Nuss,et al.  Imaging with terahertz waves. , 1995, Optics letters.

[16]  Daniel M. Mittleman,et al.  Metal wires for terahertz wave guiding , 2004, Nature.

[17]  D. Grischkowsky,et al.  Far-infrared time-domain spectroscopy with terahertz beams of dielectrics and semiconductors , 1990 .