Development of an Near-infrared and Visible Time-resolved Spectrophotometer System

本研究的目的是建立一个方便的分光光度计系统，可以测量近红外区域不稳定中间体如自由基和三重态的吸收和发射光谱。由于该区域缺乏良好的探测器，难以对其进行定量测量，因此在近红外区域的光谱研究还处于不发达阶段。在本研究中，我们试图结合Nd^<3+>: YAG激光系统，构建一个能够测量可见光和近红外吸收光谱和发射光谱的分光光度计系统。光电倍增管和锗二极管分别作为可见光和近红外区的探测器。通过对一些激光染料的光谱研究，证实了所构建的分光光度计可以得到预期的数据。本系统的功能如下：(1)光谱波长范围为可见光至近红外（400nm-1800nm）。(2)时间分辨率-20ns。(3)对分光光度计系统进行控制，并用微机对实验数据进行处理。利用我们的近红外分光光度计系统，对γ辐照聚乙烯醇薄膜中生产的口山酮、苯甲酰萘酮、二苯并啶丙酮和黄酮的半醌自由基进行了吸收光谱和荧光光谱研究。首先，这些自由基的几个吸收带和荧光带都在近红外区。长波长的位置是这些自由基的荧光光谱直到最近才被测量的原因。我们首次成功地测量了这些自由基的荧光光谱。还发现这些自由基的荧光寿命短于激光激发激光的脉宽（8ns）。

The purpose of this research is to construct a convenient spectrophotometer system which is able to measure the absorption and emission spectra of unstable intermediates such as radicals and triplet states in near-infrared region. Because of lack of a good detector in this region, it has been difficult to measure them quantitatively and therefore the spectroscopic study in near-infrared region has stayed in an undeveloped stage.In this research, we tried to construct a spectrophotometer system which is able to measure absorption spectro and emission specctra in visible and near-infrared region, in combination with a Nd^<3+> : YAG laser system. A photomultiplier and a germanium diode were used as the detectors in visible and near infrared region, respectively. By studying the spectra of some laser dyes, it was confirmed that the expected data were obtained by the constructed spectrophotometer.The ability of our system is as follows ;(1) Spectral wavelength region is from visible to near infrared (400nm-1800nm).(2) Time resolution is -20ns.(3) The spectrophotometer system is controlled and the experimental data are processed by a microcomputer.By use of our near-infrared spectrophotometer system, absorption and fluorescence spectra, and fluorescence lifetimes of semiquinone radicals of xanthone, benzoylnaphthone, dibenzilidene acetone and flavone produced in poly (vinyl alcohol) films by gamma-irraidation. Fist several absorption bands and therefore the fluorescence bands of these radicals are in near-infrared region. The long wavelength location is the reason why the fluorescence spectra of these radicals have not been measured until very recently.We succeeded in measuring the fluorescence spectra of these radicals for the first time. It was also found that the fluorescence lifetimes of these radicals are shorter than the pulse width of laser excitation laser (8ns).