Kim Hack-Sung, Stair Peter C
Department of Chemistry, Center for Catalysis and Surface Science and Institute for Catalysis and Energy Processes, Northwestern University, Evanston, Illinois 60208, USA.
J Phys Chem A. 2009 Apr 23;113(16):4346-55. doi: 10.1021/jp811019c.
We present detailed resonance Raman spectroscopic results excited at 220 and 287 nm for alumina-supported VO(x) catalysts. The anharmonic constant, harmonic wavenumber, anharmonic force constant, bond dissociation energy, and bond length change in the excited state for double bonded VO and single bonded V-O were obtained from fundamental and overtone frequencies. Totally symmetric and nontotally symmetric modes could be discerned and assigned on the basis of the overtone and combination progressions found in the resonance Raman spectra. Selective resonance enhancement of two different vibrational modes with two different excitation wavelengths was observed. This allowed us to establish a linear relationship between charge transfer energy and VO bond length and, consequently, to assign the higher-energy charge transfer band centered around 210-250 nm in the UV-vis spectra to the VO transition.
我们展示了在220和287nm激发下，用于氧化铝负载的VO(x)催化剂的详细共振拉曼光谱结果。通过基频和谐波频率获得了双键VO和单键V - O在激发态下的非谐常数、谐波波数、非谐力常数、键解离能和键长变化。基于共振拉曼光谱中发现的泛音和组合进展，可以辨别和归属完全对称和非完全对称模式。观察到两种不同激发波长对两种不同振动模式的选择性共振增强。这使我们能够建立电荷转移能量与VO键长之间的线性关系，从而将紫外可见光谱中以210 - 250nm为中心的高能电荷转移带归属于VO跃迁。
