Thermal Desorption and Reaction of NO Adsorbed on Rhodium Cluster Ions Studied by Thermal Desorption Spectroscopy

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• 作者：Yuki Tawaraya ; Satoshi Kudoh ; Ken Miyajima ; Fumitaka Mafun茅
• 刊名：Journal of Physical Chemistry A
• 出版年：2015
• 出版时间：August 6, 2015
• 年：2015
• 卷：119
• 期：31
• 页码：8461-8468
• 全文大小：463K
• ISSN：1520-5215

文摘

Cationic rhodium clusters, Rh_n⁺ (n = 4鈥?), were prepared in the gas phase by the laser ablation of a Rh rod. The Rh_n⁺ clusters were introduced into a reaction gas cell filled with nitric oxide (NO) diluted with He, where they were subjected to collisions with NO and He in a thermal equilibrium at 300 K. The NO molecules were found to adsorb sequentially on the Rh_n⁺ clusters forming Rh_n⁺(NO)_m. To examine the adsorption form and the reaction of NO, we heated Rh_n⁺(NO)_m in an extension tube located after the reaction gas cell and the thermal response of the clusters, desorption of the fragments, was recorded as a function of temperature (300鈥?000 K). The desorption of NO molecules was predominantly observed below 500 K, giving either Rh_n⁺(NO)_n+1 or Rh_n⁺(NO)_n+2, which indicates that there were NO molecules loosely adsorbed on the Rh_n⁺ clusters. Further desorption was found to proceed at higher temperatures (500鈥?000 K), whereby NO was released from the smaller clusters, Rh_n⁺ (n 鈮?5). In contrast, for the larger clusters (n 鈮?6), N₂ release was clearly observed at high temperatures (>800 K). Thus, the reduction of NO occurred for larger clusters at higher temperatures.