| Since 1999, A.H.Zewail won the Nobel Prize in Chemistry by using ultra-short laser flash technique to observe the atoms movement in chemical reactions.The time-resolved difference absorption spectra began to come into view. With this technology, the difference absorption spectroscopy has become one of the important ways of ultrafast phenomena research. Time-resolved difference absorption spectra the core of light source, light path and detector. By doing reasearching and correction of the light source, light path and detector.It is possible to improve the accuracy of difference absorption spectroscopy.The main work of this dissertation:Firstly, with the origin, development and measurement principles of time-resolved difference absorption spectra is pointed out the difference absorption spectra, together with the idea of correction composed by three parts:light source, light path and detection.Secondly, The comparison, the the structure, principle and characteristics of femtosecond and nanosecond laser pulse showed that the structure and principle of the nanosecond pulsed laser is more simple,as well as the interactions with matter, which makes for the convenience of the analysis of experimental results. Therefore, it is more suitable for calibration experiments.Thirdly, Through using dielectric film splitting devices with optical delay line for light split on time and opening screen for light split in space the differences absorption spectroscopy is corrected. The results show that(?)the idea of light split on time has big fluctuation,while the idea of light split in space doing a better calibration of the optical parts.Finally, the measurement principle, technical parameters and the characteristics of detection of PIN detector and CCD detector are well investigated and copmared.. It is founded that it is better to use CCD detectorwith a large photosensitive surface is more suitable for a light source system with large output spot and obvious spot drift... |
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