Efficiency of energy transfer in protonated diglycine and dialanine SID

Classical trajectory simulations are performed to study energy transfer in collisions of protonated diglycine, (gly) 2 H + , and dialanine, (ala) 2 H + , ions with the diamond {1 1 1} 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, Δ E int , and to the surface, Δ E surf , and of energy remaining in peptide ion translation, E f , are very similar for (gly) 2 H + and (ala) 2 H + . The average percent energy transferred to Δ E surf and E f increases and decreases, respectively, with increase in E i . Average energy transfer to Δ E int is less dependent on E i , but does decrease with increase in E i . The AMBER and AM1 models for the (gly) 2 H + intramolecular potential give statistically identical energy transfer distributions in (gly) 2 H + + diamond {1 1 1} collisions. A comparison of the current study with previous trajectory simulations of glyH + , (gly) 3 H + , and (gly) 5 H + collisions with diamond {1 1 1} shows that the energy transfer efficiencies to Δ E int , Δ E surf , and E f are similar for (gly) n H + , n =1–5. The energy transfer distributions for (gly) 2 H + + diamond {1 1 1} 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°.