Yang Y, Kühn O, Santambrogio G, Goebbert D J, Asmis K R
Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, D-14195 Berlin, Germany.
J Chem Phys. 2008 Dec 14;129(22):224302. doi: 10.1063/1.3028211.
The gas phase vibrational spectroscopy of the protonated ammonia dimer N(2)H(7)(+), a prototypical system for strong hydrogen bonding, is studied in the spectral region from 330 to 1650 cm(-1) by combining infrared multiple photon dissociation and multidimensional quantum mechanical simulations. The fundamental transition of the antisymmetric proton stretching vibration is observed at 374 cm(-1) and assigned on the basis of a six-dimensional model Hamiltonian, which predicts this transition at 471 cm(-1). Photodissociation spectra of the larger protonated ammonia clusters NH(4)(+)(NH(3))(n) with n=2-4 are also reported for the range from 1050 to 1575 cm(-1). The main absorption features can be assigned within the harmonic approximation, supporting earlier evidence that hydrogen bonding in these clusters is considerably weaker than for n=1.
质子化氨二聚体N₂H₇⁺是强氢键作用的典型体系,通过结合红外多光子解离和多维量子力学模拟,在330至1650 cm⁻¹光谱区域研究了其气相振动光谱。在374 cm⁻¹处观测到反对称质子伸缩振动的基频跃迁,并基于六维模型哈密顿量进行了归属,该模型哈密顿量预测此跃迁在471 cm⁻¹处。还报道了n = 2 - 4的较大质子化氨簇NH₄⁺(NH₃)ₙ在1050至1575 cm⁻¹范围内的光解离光谱。主要吸收特征可在简谐近似下进行归属,支持了早期的证据,即这些簇中的氢键作用比n = 1时弱得多。