Temperature Dependent Absorption Spectra of Br鈭?/sup>, Br2鈥⑩垝, and Br3鈭?/sup> in Aqueous Solutions
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- 作者：Mingzhang Lin ; Pierre Archirel ; Nguyen Thi Van-Oanh ; Yusa Muroya ; Haiying Fu ; Yu Yan ; Ryuji Nagaishi ; Yuta Kumagai ; Yosuke Katsumura ; Mehran Mostafavi
- 刊名：Journal of Physical Chemistry A
- 出版年：2011
- 出版时间：May 5, 2011
- 年：2011
- 卷：115
- 期：17
- 页码：4241-4247
- 全文大小：951K
- 年卷期：v.115,no.17(May 5, 2011)
- ISSN：1520-5215
文摘
The absorption spectra of Br2鈥⑩垝 and Br3鈭?/sup> in aqueous solutions are investigated by pulse radiolysis techniques from room temperature to 380 and 350 掳C, respectively. Br2鈥⑩垝 can be observed even in supercritical conditions, showing that this species could be used as a probe in pulse radiolysis at high temperature and even under supercritical conditions. The weak temperature effect on the absorption spectra of Br2鈥⑩垝 and Br3鈭?/sup> is because, in these two systems, the transition occurs between two valence states; for example, for Br2鈭?/sup> we have 2危u 鈫?2危g transition. These valence transitions involve no diffuse final state. However, the absorption band of Br鈭?/sup> undergoes an important red shift to longer wavelengths. We performed classical dynamics of hydrated Br鈭?/sup> system at 20 and 300 掳C under pressure of 25 MPa. The radial distribution functions (rdf's) show that the strong temperature increase (from 20 to 300 掳C) does not change the radius of the solvent first shell. On the other hand, it shifts dramatically (by 1 脜) the second maximum of the Br鈭扥 rdf and introduces much disorder. This shows that the first water shell is strongly bound to the anion whatever the temperature. The first two water shells form a cavity of a roughly spherical shape around the anion. By TDDFT method, we calculated the absorption spectra of hydrated Br鈭?/sup> at two temperatures and we compared the results with the experimental data.