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The paper summarizes the research progress of analytical method of sulfur element in iron-base alloys as of 2012. Major analytical methods for sulfur element in iron-base alloys include infrared absorption, photoelectric direct reading spectrometry, inductively coupled plasma atomic emission spectrometry, ion chromatography method, mass-spectrography, and electrochemical method. The paper also predicts the future trend of the analytical methods for sulfur element in iron-base alloys.

This paper focuses on discussing the principle of detecting carbon and sulphur by using infrared absorption method, characteristics of high-frequency heating, system blank value, and method for detecting trace carbon and sulphur.

The detection of carbon with the contents ranging from 0. 000 5 % to 0.010%, and of sulfur with the contents ranging from 0.000 2% to 0.010%, has become an inevitable requirement for steelmaking process control. Due to the extreme low carbon and sulfur contents, using infrared carbon sulfur technical analysis has lower peak value than the background value of the instrument, and it is difficult to control the best analysis conditions of obtained valid signal; in addition, the small errors brought by crucible blank, sample weight, and uniformity of the samples may have great impact on the detection results. To solve this technical problem, this study gives up the single point calibration applied by infrared absorption method, but uses linear calibration method to detect ultra low carbon and sulfur contents in steel, which effectively meets the demand of manufacturers on the development of high-value-added products, and provides reliable data for production.

We theoretically analyze the steady state emission spectrum and transient temporal dynamics in a coupled biexciton quantum dot (QD)—cavity system. For steady state, a phonon-assisted biexciton—exciton cascade model under continuous wave (CW) excitation is presented to explain the asymmetric QD—cavity emission spectrum intensities (intensities of cavity, exciton, and biexciton emission peak) in off-resonance condition. Results demonstrate that the electron—phonon process is crucial to the asymmetry of emission spectrum intensity. Moreover the transient characteristics of the biexciton—exciton cascade system under pulse excitation show abundant nonlinear temporal dynamic behaviors, including complicated oscillations which are caused by the four-level structure of QD model. We also reveal that under off-resonance condition the cavity outputs are slightly reduced due to the electron—phonon interaction.