Sarma Manabendra, Adhikari S, Mishra Manoj K
Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.
J Chem Phys. 2007 Jan 28;126(4):044309. doi: 10.1063/1.2431652.
Vibrational excitation (nu(f)<--nu(i)) cross-sections sigma(nu(f)<--nu(i) )(E) in resonant e-N(2) and e-H(2) scattering are calculated from transition matrix elements T(nu(f),nu(i) )(E) obtained using Fourier transform of the cross correlation function <phi(nu(f) )(R)|psi(nu(i))(R,t)>, where psi(nu(i))(R,t) approximately =e(-iH(A(2))-(R)t/h phi(nu(i))(R) with time evolution under the influence of the resonance anionic Hamiltonian H(A(2) (-))(A(2) (-)=N(2)(-)/H(2) (-)) implemented using Lanczos and fast Fourier transforms. The target (A(2)) vibrational eigenfunctions phi(nu(i))(R) and phi(nu(f))(R) are calculated using Fourier grid Hamiltonian method applied to potential energy (PE) curves of the neutral target. Application of this simple systematization to calculate vibrational structure in e-N(2) and e-H(2) scattering cross-sections provides mechanistic insights into features underlying presence/absence of structure in e-N(2) and e-H(2) scattering cross-sections. The results obtained with approximate PE curves are in reasonable agreement with experimental/calculated cross-section profiles, and cross correlation functions provide a simple demarcation between the boomerang and impulse models.
在共振电子与N₂和电子与H₂散射中，振动激发（ν(f)←ν(i)）截面σ(ν(f)←ν(i))(E)是根据跃迁矩阵元T(ν(f),ν(i))(E)计算得出的，而跃迁矩阵元T(ν(f),ν(i))(E)是通过互相关函数〈φ(ν(f))(R)|ψ(ν(i))(R,t)〉的傅里叶变换得到的，其中ψ(ν(i))(R,t)≈e^(-iH(A₂)(R)t/ħ)φ(ν(i))(R)，在共振阴离子哈密顿量H(A₂⁻)(A₂⁻ = N₂⁻/H₂⁻)的影响下随时间演化，这是使用兰索斯算法和快速傅里叶变换实现的。目标（A₂）的振动本征函数φ(ν(i))(R)和φ(ν(f))(R)是使用傅里叶网格哈密顿量方法计算得到的，该方法应用于中性目标的势能（PE）曲线。将这种简单的系统化方法应用于计算电子与N₂和电子与H₂散射截面中的振动结构，为电子与N₂和电子与H₂散射截面中结构存在/不存在的潜在特征提供了机理见解。用近似PE曲线得到的结果与实验/计算的截面轮廓合理吻合，并且互相关函数在回飞镖模型和脉冲模型之间提供了一个简单的划分。
