[LED illuminant-based detection of trace NO2 gases].

Light-emitting diode was used as illuminant in the present paper. The light-emitting diode was chosen according to the high absorption in the range of absorption spectrum of NO2. The pollutant concentration can be calculated by measuring the absorption spectrum, and fitting the experimental absorption spectrum and normal absorption spectrum by means of least square fitting method. The method of measuring nitrogen dioxide concentration making use of absorption spectra was studied, the basic principle was analyzed, the process of data analysis was studied including the fitting of experimental spectrum and standard spectrum, wiping off the slow change, using least-square fitting in reverse calculating of concentration etc. The detecting precision was improved by the method of absorption spectrum. In this experiment the light emitting diode was used as illuminant, which made the detecting become not only convenient but also fast, and online real time supervising can be realized. Taking advantage of the characteristic that NO2 has strong absorption in the range of 300-500nm, the NO2 concentration of sample was measured.

[FTIR spectroscopic studies of inner stress on boron carbon nitride thin films].

Boron carbon nitride thin films were deposited by radio frequency (RF) magnetron sputtering technique using a 50 mm-diameter composite target consisting of h-BN and graphite in an Ar-N2 gas mixture. The composite target was composed of two semi disks: one of h-BN and the other one of graphite. The distance between the target and the substrate was kept at 50 mm. The chamber base pressure was below 5 x 10(-4) Pa. During the deposition, the mixture of Ar (80%) and N2 (20%) was injected into the vacuum chamber and the total pressure was 1.3 Pa. The films were grown on silicon substrates at different deposition parameters, including sputtering power of 80-130 W, deposition temperature of 300-500 degrees C and deposition time of 1-4 h. The chemical bonding state of the samples was characterized by Fourier transform infrared absorption spectroscopy (FTIR). The results suggested that all of the films deposited at these deposition parameters are atomic-level hybrids composed of B, C and N atoms. Besides BN and carbons bonds, the boron carbide and carbon nitride bonds were formed in the BCN thin films. And the deposition parameters have important influences on the growth and inner stress of BCN thin films. That is the higher the sputtering power, the larger the inner stress; the higher or lower the deposition temperature, the larger the inner stress; the longer the deposition time, the larger the inner stress. So changing deposition parameters properly is a feasible method to relax the inner stress between the films and substrate. In the conditions of changing one parameter each time, the optimum deposition parameters to prepare BCN thin films with lower inner stress were obtained: sputtering power of 80 W, deposition temperature of 400 degrees C and deposition time of 2 h.

[The study of infrared absorption spectrum of diamond during growth by FTIR].

The diamond thin films were deposited on silicon substrates under invariable conditions of process pressure, substrate temperature negative direct-current (dc) bias of substrate and microwave power while the rations of methane (CH4) to hydrogen (H2) changing from 3% to 5% and 9% using electron-cyclotron-resonance microwave plasma-assisted chemical vapor deposition technique (ECRCVD). In situ Fourier transform infrared spectroscopy (FTIR) have been used to study the plasma species absorbed on the substrate surfaces as well as the species above the substrates surfaces both before and during the nucleation and film growth. It is demonstrated that these techniques can provide useful information on the early stages of diamond growth. When correlated with film properties measured by Raman spectroscopy and scanning electron microscopy, the results from FTIR indicate that the absorption of the graphitic and diamond phases are related to the ratio of CH4 to H2 and can be identified at the early stages of film growth.

[Study on spectral property of phase transition of PcNi-VO2 films].

Highly oriented VO2 thin films were deposited on sapphire substrate and [C8H17O]8 PcNi thin films were spin-coated onto VO2 thin films. The microstructure of VO2 thin films was studied with XRD. The phase transition was observed and the change in the optical properties of the PcNi/VO2 multilayer-films were investigated with infrared spectrometer. It was found that the mid-infrared transmittance of the complex films in the wavelength range 1.5 to 5.5 mm raised with PcNi coating. The thermochromism of PcNi/VO2 films did not changed compared with VO2 films and the transition temperature was the same as that of VO2. It can be anticipated that the optical limiting property of PcNi/VO2 films will be superior to that of VO2 thin films or PcNi thin films.

[Study on temperature character of stimulated Raman scattering spectrum in silica fiber].

Stimulated Raman scattering (SRS) spectrum of silica fiber was studied under different temperatures. The influence of temperature on feature of SRS spectra was analyzed theoretically and experimentally. The laws of how the Raman frequency-shift, bandwidth and intensity of the first order Stokes light change with the temperature were obtained using a pulsed Q-switched doubled frequency laser. The experiments indicate that the frequency-shift becomes bigger with the increasing the temperature. Raman frequency-shift has a linear relationship with the temperature. Under the same pump power, when the temperature is lower, the order of SRS spectrum is lower. Lower temperature has high order Stokes light. For higher order Stokes lights, the lower the temperature, the higher the threshold. But the changes in spectrum bandwidth show no linear relationship with the temperature, and there is a maximum of bandwidth. Theory and experiments indicate that temperature has direct effect on the SRS of fiber.

[Ultraviolet transmission spectra of BC(x)N thin films].

BCN, BC2N and BC3N thin films with transmission increasing properties in the ultraviolet region were deposited by RF magnetron sputtering with different sputtering power (80-130 W). Fourier transform infrared absorption and X-ray photoelectron spectroscopy results suggested that the films were atomnic-level hybrids composed of B, 'C and N atoms. The compositions and transmission increasing properties of samples in the ultraviolet region were strongly influenced by sputtering power, which determined the transmission increasing properties in the ultraviolet region by changing compositions. And the lower the atomic number of C in the thin films, the better the transmission increasing properties in the ultraviolet region. The BCN thin films deposited at the sputtering power of 110 W possessed the lowest atonic number of C and the best transmission increasing properties in the ultraviolet region. And the increase in average transmissivity from 200 to 350 nm was about 40% compared with glass.

[Study of Raman scattering of plastic optical fiber].

The first order stimulated Raman scattering (SRS) spectrum of PMMA plastic optical fiber was given, and the characteristic of the first order Stokes spectrum was studied. The threshold and the spectrum width were measured. The formation mechanism of SRS was analyzed, and then the first order Stokes spectrum of plastic optical fiber and that of silica fiber were compared.