Efficiency of energy transfer in protonated diglycine and dialanine SID Effects of collision angle, peptide ion size, and intramolecular potential

摘要

Classical trajectory simulations are performed to study energy transfer in collisions of protonated diglycine, (gly)_2H~+, and dialanine, (ala)_2H~+, ions with the diamond {111} surface, for a collision energy E_i in the range of 5-110 eV and incident angles of 0 and 45°with respect to the surface normal. The distribution of energy transfer to vibrational/rotational degrees of freedom, ΔE_(int), and to the surface, ΔE_(surf), and of energy remaining in peptide ion translation, E_f, are very similar for (gly)_2H~+ and (ala)_2H~+. The average percent energy transferred to ΔE_(surf) and E_f increases and decreases, respectively, with increase in E_i. Average energy transfer to ΔE_(int) is less dependent on E_i, but does decrease with increase in E_i. The AMBER and AM1 models for the (gly)_2H~+ intramolecular potential give statistically identical energy transfer distributions in (gly)_2H~+ + diamond {111} collisions. A comparison of the current study with previous trajectory simulations of glyH~+, (gly)_3H~+, and (gly)_5H~+ collisions with diamond {111} shows that the energy transfer efficiencies to ΔE_(int), ΔE_(surf), and E_f are similar for (gly)_nH~+, n = 1-5. The energy transfer distributions for (gly)_2H~+ + diamond {111} collisions depend on the collision angle and do not scale in accord with the normal component of the collision energy E_i~n for collisions with θ_i of 0 and 45°.