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Direct observation of bond formations

Date:
February 19, 2015
Source:
High Energy Accelerator Research Organization/KEK
Summary:
Direct "observation" of the bond making, through a chemical reaction, has been longstanding dream for chemists. However, the distance between atoms is very small, at about 100 picometer, and the bonding is completed very quickly, taking less than one picosecond (ps). Hence, previously, one could only imagine the bond formation between atoms while looking at the chemical reaction progressing in the test-tube. In this research, scientists directly observed a very fast chemical reaction, induced by photo-excitation.
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This chart outlines observed changes in the molecular structure of the gold complex.
Credit: KEK

A collaboration between researchers from KEK, the Institute for Basic Science (IBS), the Korea Advanced Institute of Science and Technology (KAIST), RIKEN, and the Japan Synchrotron Radiation Research Institute (JASRI) used the SACLA X-ray free electron laser (XFEL) facility for a real time visualization of the birth of a molecule that occurs via photo-induced formation of a chemical bonds. This achievement was published in the online version of the scientific journal Nature (published on 19 February 2015).

Direct "observation" of the bond making, through a chemical reaction, has been longstanding dream for chemists. However, the distance between atoms is very small, at about 100 picometer, and the bonding is completed very quickly, taking less than one picosecond (ps). Hence, previously, one could only imagine the bond formation between atoms while looking at the chemical reaction progressing in the test-tube.

In this study, the research group focused on the process of photoinduced bond formation between gold (Au) ions dissolved in water. In the ground state  Au ions that are weakly bound to each other by an electron affinity and aligned in a bent geometry. Upon a photoexcitation, the S0 state rapidly converts into an excited state where Au-Au covalent bonds are formed among Au ions aligned in a linear geometry. Subsequently, the S1 state transforms to a triplet state  in 1.6 ps while accompanying further contraction of Au-Au bonds by 0.1 Å. Later, the T1 state of the trimer converts to a tetramer on nanosecond time scale. Finally, the Au ions returned to their original loosely interacting bent structure.

In this research, scientists directly observed a very fast chemical reaction, induced by the photo-excitation. Therefore, this method is expected to be a fundamental technology for understanding the light energy conversion reaction. The research group is actively working to apply this method to the development of viable renewable energy resources, such as a photocatalysts for artificial photosynthesis using sunlight.


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Materials provided by High Energy Accelerator Research Organization/KEK. Note: Content may be edited for style and length.


Journal Reference:

  1. Kyung Hwan Kim, Jong Goo Kim, Shunsuke Nozawa, Tokushi Sato, Key Young Oang, Tae Wu Kim, Hosung Ki, Junbeom Jo, Sungjun Park, Changyong Song, Takahiro Sato, Kanade Ogawa, Tadashi Togashi, Kensuke Tono, Makina Yabashi, Tetsuya Ishikawa, Joonghan Kim, Ryong Ryoo, Jeongho Kim, Hyotcherl Ihee, Shin-ichi Adachi. Direct observation of bond formation in solution with femtosecond X-ray scattering. Nature, 2015; 518 (7539): 385 DOI: 10.1038/nature14163

Cite This Page:

High Energy Accelerator Research Organization/KEK. "Direct observation of bond formations." ScienceDaily. ScienceDaily, 19 February 2015. <www.sciencedaily.com/releases/2015/02/150219115815.htm>.
High Energy Accelerator Research Organization/KEK. (2015, February 19). Direct observation of bond formations. ScienceDaily. Retrieved May 23, 2017 from www.sciencedaily.com/releases/2015/02/150219115815.htm
High Energy Accelerator Research Organization/KEK. "Direct observation of bond formations." ScienceDaily. www.sciencedaily.com/releases/2015/02/150219115815.htm (accessed May 23, 2017).

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