Abstract-Development of a Novel Metal Grating and Its Applications of Terahertz Spectroscopic Detection of CuSO4 in Fruit

 

Yanqun Tong, Shiyan Wang, Kuiguo Han, Xiaoxian Song, Wen Zhang, Yunxia Ye,  Xudong Ren 

https://link.springer.com/article/10.1007/s12161-021-01999-1

As a novel detection method of CuSO4, terahertz (THz) spectroscopy detection has great application prospects, but the terahertz detection with the tablet method has low sensitivity, and with the metamaterials has complicated manufacture. This work has proposed a high-sensitivity pesticide THz spectroscopic detection method with a novel metal grating. The metal grating was composed of a circular hole array. It was made by laser micromachining technology to provide a simplified but improved measurement and had a strong transmission peak at the 0.4–1.0 THz band. The results indicated that the addition of copper sulfate (CuSO4) solutions to different concentrations caused the transmission peak frequency to shift red. The detection limit was about 103 times higher than that of CuSO4 measured on the polyethylene (PE) film substrate, which reached 0.375 mg/L. The method was applied for detecting CuSO4 in apple and grape, and the relative error was less than 5.8%. The metal grating combined with Terahertz time-domain spectroscopy (THz-TDS) can improve the sensitivity of sample detection and realize the detection and analysis of trace elements.

Abstract-Electron transfer from bi-isonicotinic acid emerges upon photodegradation of N3 sensitized TiO2 electrodes

Melike Karakus, Wen Zhang, Hans Joachim Räder, Mischa Bonn, Enrique Cánovas,

http://pubsdc3.acs.org/doi/10.1021/acsami.7b08986

The long-term stability of dye sensitized solar cells (DSSCs) is determined to a large extent by the photodegradation of their sensitizers. Understanding the mechanism of light induced decomposition of dyes sensitizing a mesoporous oxide matrix may therefore contribute to solutions to increase the life span of DSSCs. Here, we investigate, using ultrafast terahertz photoconductivity measurements, the evolution of interfacial electron transfer (ET) dynamics in N3 dye-sensitized mesoporous TiO2 electrodes upon dye photodegradation. Under inert environment, interfacial ET dynamics do not change over time, indicating that the dye is stable and photodegradation is absent; the associated ET dynamics are characterized by a sub-100 fs rise of the photo-conductivity, followed by long-lived (>>1 ns) electrons in the oxide electrode. When the N3-TiO2 sample is exposed to air under identical illumination conditions, dye photodegradation is evident from the disappearance of the optical absorption associated with the dye. Remarkably, approximately half of the sub-100 fs ET is observed to still occur, but is followed by very rapid (~10 ps) electron-hole recombination. Laser desorption/ionization mass spectrometry, attenuated total reflection FTIR and terahertz photoconductivity analyses reveal that the photo-degraded ET signal originates from the N3 dye photodegradation product as dcbpy (4,4’- dicarboxylic acid - 2,2’-bipyridine), which remains bonded to the TiO2 surface via either bidentate chelation or bridging type geometry.

A THz Superconducting Imaging Array Developed for the DATE5 Telescope

Sheng-Cai Shi, Wen Zhang, Jing Li, Wei Miao, Zhen-Hui Lin, Zheng Lou, Qi-Jun Yao

http://paperity.org/p/74626764/a-thz-superconducting-imaging-array-developed-for-the-date5-telescope

Dome A in Antarctica, located at an altitude of 4093 m and with very low temperature in winter down to −83∘C, is an exceptionally dry site. Measurements of the atmospheric transmission in the range of 0.75–15 THz by a Far-infrared/THz Fourier transform spectrometer (FTS) strongly suggest that Dome A is a unique site for ground-based THz observations, especially for the 200- and 350-micron windows. A 5-m THz telescope (DATE5) is therefore proposed for Chinese Antarctic Kunlun Observatory. We are currently developing a THz superconducting imaging array (TeSIA) for the DATE5. The TeSIA will be working at the 350-\upmum window, with a pixel number of 32×32 and a sensitivity (NEP) of ∼10−16 W/Hz0.5. Ti transition-edge sensors with time-domain multiplexing and TiN microwave kinetic inductance detectors with frequency-domain multiplexing are both developed for the TeSIA. In this paper, detailed system designs and some measurement results will be presented.