Papers by Keyword: Absorption Peak

Abstract: This paper researched the linear relationship between UV absorbance and concentrations of nitrobenzene. It used the UV-1700 UV/VIS spectroscopy to get the absorbance diagram and analyze it. Then it calculated the absorbance of maximum absorption peak and the absorbance integration in a wavelength interval. There is a linear relationship between absorbance and concentration, the correlation coefficient is 0.981 of the maximum absorption peaks and the concentrations, and the largest correlation coefficient between concentrations and the integration of absorbance is 0.995 with the wavelength interval of 235-245 nm, which is between the two absorption peaks of 210 nm and 270 nm. Therefore, it’s a good way to use integration of absorbance in the middle of two absorption peaks to measure the concentration of nitrobenzene, which is more accurate and reliable.

Abstract: Since spectral curves were obtained by experiment, on the basis of the fully use of the waveform characters, a new method for spectral matching pretreatment has been proposed in this paper. Corresponding to the spectral curve, we can accurately get the spectral absorption curve of the number of bands, it can effectively suppress the effects of the noise according to the times of fitting the points. Besides, it can also prominent the peak point of the material. This method can have an effective influence on the initial period of spectral match and detailed resolution; some numerical simulations have been made to test the validity and capability of the proposed method.

Abstract: THz spectral properties between 0.2-1.5THz of beta-endosulfan, one of the persistent organic pollutants (POPs), are investigated based on the THz time domain system. Part of the characteristic absorption peaks are theoretically analyzed by Dmol3 modular program. The experimental results show that the average refractive index of beta-endosulfan in the THz waveband is about 1.005 and characteristic absorption peaks exist at 0.67, 0.80, 1.03, 1.14, 1.26 and 1.46THz. The absorption peaks at 0.67THz and 1.03THz have a good match with the theoretic absorption peak positions which appear at 0.72THz and 1.07THz calculated by Dmol3. The peaks at 0.67THz and 1.03THz may be caused by the torsion in B and C direction of beta-endosulfan crystal lattice, along with the translation in A direction. Compared with the experimental results of alpha-endosulfan, it can be seen clearly that these two isomers have completely different absorption peaks. For further it indicates that terahertz time domain spectroscopy (THz-TDS) has great application value in identifying isomers.

Abstract: This paper reports on the effect of growth temperatures on optical properties of monodisperse CdSe QDs synthesized via wet chemical method. The growth temperature was varied from 260 – 310 °C while growth period was fixed at 60 s. The resulting colloidal was in strong quantum confinement regime and having yield as high as 53%. As the growth temperature increased, the monodispersed CdSe QDs with diameter in the range of 3-7 nm were obtained. Both absorption and PL spectra of the QDs revealed a strong red-shift with the increment of growth temperature. Thus, the size of QDs was enlarged with increment of the wavelength from both the spectra. Consequently, the energy gap of resulting QDs can be tuned by tuning the size of QDs. More importantly, the narrow widths of the PL emissions with different colors make these colloidal to be a potential candidate for different optical and optoelectronic devices.

Abstract: Microwave absorbing material is currently being more and more widely applied in the world. However, conventional absorbent coating material cannot fulfill the complex current requirements of science and technology to have a wide absorption frequency band, and high absorption. This paper describes composite material plates with a multi-layer absorbing structure designed according to impedance-matching and attenuation principles, producing two- and three-layer absorbing structures. Twelve samples were made, containing graphite powder and manganese dioxide at varying concentrations. The results show that in the frequency range 8-18 GHz, the peak absorption of double-layer samples is -12.3dB, the effective bandwidth (R < -10 dB) is 1.8GHz. The absorption peak of three-layer samples is -18 dB, and the effective bandwidth (R < -10 dB) is 8GHz. The findings of this research are useful in improving the absorption bandwidth of absorbing material.

Abstract: Using electro-optic sampling technique and THz time-domain spectroscopy-transmission equipment, the reference THz wave and the sample THz wave has been measured from 0.3 THz to 3.0 THz and the absorption index has been obtained. Absorption peaks of β-Zn₃BPO₇ crystal sample were found in four points. The important condition of direct interaction between lattice and light is that they must have the same frequency and wave vector, also lattice vibration mode should be transverse because the light is electromagnetic wave. The absorption peaks are found multiple of the optical phonon basically after calculation. The sample shows great resonance absorption.