Reduction of nitric acid on Ag in ultrahigh vacuum: A Raman spectroscopic investigation

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• 作者：Christopher D. Zangmeister ; Robert J. Davis ; Pawel Mrozek ; Jeanne E. Pemberton
• 关键词：Surface chemical reaction ; Nitrogen oxides ; Raman scattering spectroscopy
• 刊名：Surface Science
• 出版年：2008
• 出版时间：15 July 2008
• 年：2008
• 卷：602
• 期：14
• 页码：2395-2401
• 全文大小：338 K

文摘

The reduction of HNO₃ on Ag as a function of temperature in ultrahigh vacuum (UHV) is studied using Raman spectroscopy and thermal desorption-mass spectrometry (TDMS). Thin layers of molecular HNO₃ are stable on the surface below 150 K, but are spontaneously reduced above 150 K with concomitant time-dependent partial desorption of products. The asymmetric nitric oxide dimer, NONO, is observed as the sole reduction product that remains on the surface based on its distinctive Raman spectral signature. The mechanism of NONO formation from HNO₃ is proposed to occur through a multistep reduction of HNO₃ on the Ag surface starting from and proceeding stepwise through NO₂ and to NO, followed by combination to form NONO in a process catalyzed by a Lewis acid, oxidized Ag species. Desorption of the majority of surface species is largely complete by 210 K.