Rahaman Asif, Collins Othalene, Scott Chavell, Wang Jiangping, Hase William L
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, USA.
J Phys Chem A. 2006 Jul 13;110(27):8418-22. doi: 10.1021/jp057159o.
The effects of temperature on energy transfer during collisions of protonated diglycine ions, Gly(2)-H(+), with a diamond {111} surface were investigated by chemical dynamics simulations. The simulations were performed for a collision energy of 70 eV and angle of 0 degrees with respect to the surface normal. In one set of simulations the initial surface temperature, T(surf), was varied from 300 to 2000 K, while the Gly(2)-H(+) vibrational and rotational temperatures were maintained at 300 K. For the second set of simulations the Gly(2)-H(+) vibrational temperature, T(vib), was varied from 300 to 2000 K, keeping both the Gly(2)-H(+) rotational and surface temperatures at 300 K. Increasing either the surface temperature or Gly(2)-H(+) vibrational temperature to values as high as 2000 K has, at most, only a negligible effect on the partitioning of the incident collision energy to the surface and to the vibrational and rotational modes of Gly(2)-H(+). To a good approximation, the initial surface and peptide ion energies are nearly adiabatic during the collisional energy transfer. This adiabaticity of the initial peptide ion energy agrees with experiments (J. Phys. Chem. A 2004, 108, 1). A more quantitative analysis of the effects of T(vib) and T(surf) shows there are small, but noticeable, effects on the energy transfer efficiencies. Namely, increasing the vibrational or surface temperature results in a near-linear decrease in the energy transfer to the degrees of freedom associated with this temperature.
通过化学动力学模拟研究了质子化双甘氨酸离子Gly(2)-H(+)与金刚石{111}表面碰撞过程中温度对能量转移的影响。模拟是在相对于表面法线的碰撞能量为70 eV且角度为0度的条件下进行的。在一组模拟中，初始表面温度T(surf)在300至2000 K之间变化，而Gly(2)-H(+)的振动和转动温度保持在300 K。在第二组模拟中，Gly(2)-H(+)的振动温度T(vib)在300至2000 K之间变化，同时将Gly(2)-H(+)的转动温度和表面温度都保持在300 K。将表面温度或Gly(2)-H(+)的振动温度提高到高达2000 K，对入射碰撞能量分配到表面以及Gly(2)-H(+)的振动和转动模式上，至多只有可忽略不计的影响。在碰撞能量转移过程中，初始表面和肽离子能量在很好的近似下几乎是绝热的。初始肽离子能量的这种绝热性与实验结果相符（《物理化学杂志A》2004年，第108卷，第1期）。对T(vib)和T(surf)影响的更定量分析表明，对能量转移效率存在小但明显的影响。也就是说，提高振动或表面温度会导致与此温度相关的自由度的能量转移几乎呈线性下降。
