Photo-induced Structural Change and the Relaxation in Liquid Sulfur

光致结构变化和液态硫的弛豫

• 批准号: 07454066
• 负责人: TAMURA Kozaburo
• 金额: $ 0.32万
• 依托单位: HIROSHIMA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07454066/
• 关键词: liquid sulfur; photo-induced polymerization; transient absorption spectra; photo-induced semiconductor-metal transition; 過度吸収スペクトル; 光誘起半導体一金属転移; 鎖状高分子

We have studied what happens in the structural and electronic properties of liquid chalcogens such as S and Se when we remove LP electrons by the photo-excitation.It is well known that liquid S forms a light yellow liquid consisting of S_8 molecules, which has the shape of puckered ring, between the melting point (113ﾟC) and the polymerization temperature Tp (159ﾟC). We have found that liquid S is very photo-sensitive and a distinct photo-induced structural change occurs when the pulsed laser with a wave length of 355 nm illuminates below Tp. With increasing intensity of laser we have observed three different structural changes : (1) A charge transfer complex is produced when the intensity is less than 10 mJ/pulse. (2) A polymer is produced when the intensity is more than 10 mJ/pulse. (3) When the intensity is more than 20 mJ/pulse we have observed another interesting phenomena, namely, the illuminated region appears in the visible light like rainbow. Studies using a microscope revealed an inhomogeneous region where a giant-molecule seems to be generated. It was found, furthermore, that the two-dimensional restriction of the optical cell less than 0.1 micron in which liquid S is contained plays an important role when the giant-molecules are generated. The geometrical restriction may force the giant-molecules to have an ordered structure.We have also found a strong photo-darkening for liquid Se, that is, an enormous reduction exceeding 50% in the transmittance when the pulsed laser with band gap energy illuminates. The results of the transient absorption spectra suggest the possibility that the illumination of laser induces the structural instability of liquid Se eventually causing the semiconductor-metal transition.

我们研究了用光激发去除LP电子对S、Se等液体硫族化合物的结构和电子性质的影响。众所周知，液体S在熔点(113ﾟC)和聚合温度Tp(159ﾟC)之间形成了由S_8分子组成的淡黄色液体，其形状为褶皱环状。我们发现，液体S是非常光敏的，当波长为355 nm的脉冲激光照射到Tp以下时，会发生明显的光致结构变化。随着激光强度的增加，我们观察到了三种不同的结构变化：(1)当激光强度小于10mJ/脉冲时，产生电荷转移络合物。(2)当激光强度大于10mJ/脉冲时，产生聚合物。(3)当激光强度大于20mJ/脉冲时，我们观察到了另一个有趣的现象，即被照亮的区域在可见光中出现彩虹。使用显微镜的研究揭示了一个不均匀的区域，在那里似乎产生了一个巨大的分子。此外，还发现，在产生大分子时，含有S液体的小于0.1微米的光学元件的二维限制起到了重要作用。几何限制可能会迫使大分子具有有序结构。我们还发现了对液体Se的强烈光致变暗，即当具有带隙能量的脉冲激光照射时，透过率大大降低超过50%。瞬时吸收光谱的结果表明，激光的照射可能导致液体Se的结构不稳定，最终导致半导体-金属相变。

项目成果

K. Tamura: "Semiconductor-metal Transition in Fluid Selenium" Proceedings of the First chinese Conference on Liguia physies, Beijing, 1996.(in press).

K. Tamura：“流体硒中的半导体-金属转变”第一届中国Liguia物理学会议论文集，北京，1996年。（正在出版）。

Y.Sakaguchi: "Photoinduced Polymerization and Relaxation in Liquid Sulphur" Journal of Physics : Condenced Matter. Vol.7. 4787-4801 (1995)

Y.Sakaguchi：“液态硫中的光致聚合和弛豫”物理学杂志：凝聚态物质。

坂口佳史: "液体イオウにおける光誘起重合化とその緩和" 広島大学総合科学部紀要IV理系編. 第20巻. 131-152 (1994)

Yoshifumi Sakaguchi：“液体硫中的光诱导聚合及其松弛”广岛大学综合艺术与科学学院通报 IV 科学版。第 20 卷 131-152（1994 年）。

K.Tamura: "Simiconductor-metal Transition in Fluid Selenium" Proceedings of the First Chinese Conference on Liquid Physics, Beijing. (in press). (1996)

K.Tamura：“流体硒中的半导体-金属转变”第一届中国液体物理学会议论文集，北京。

K.Tamura: "Semiconductor-metal Transition in Fluid Selenium" Proceedings of the First Chinese Conference on Liquid Physics,Beijing. in press. (1996)

K.Tamura：“流体硒中的半导体-金属转变”第一届中国液体物理学会议论文集，北京。