Observation of Magic Number Clusters from Thermal Dissociation Molecular Dynamics Simulations of Lithium Formate Ionic Clusters

Molecular dynamics
(MD) simulations are well positioned to elucidate
the aspects of electrospray ionization (ESI) and high-energy collision
dissociation (HCD), as well as give insight into processes that involve
neutral species that cannot be observed experimentally in ESI, HCD,
and collision-induced dissociation (CID). Here, we utilize temperature
dissociation molecular dynamics (TDMD) to model the HCD/CID of lithium
formate clusters carrying a single positive charge. These simulations
successfully reproduce the experimental ESI HCD spectra of lithium
formate solutions and also support the existence of magic number clusters
(MNCs) that have been observed. The simulations also provide strong
evidence that the main fragmentation channel of such clusters involves
neutral (LiHCOO)2 dimers.

分子动力学（MD）模拟在阐明电喷雾电离（ESI）与高能碰撞解离（HCD）的相关机制方面具备显著优势，同时还可揭示那些无法通过ESI、HCD及碰撞诱导解离（CID）实验观测到的涉及中性物种的过程。本文采用温解分子动力学（TDMD）方法，对携带单个正电荷的甲酸锂团簇的HCD/CID过程进行建模。该模拟成功复现了甲酸锂溶液的实验ESI-HCD谱图，同时佐证了已观测到的幻数团簇（MNCs）的存在。此外，模拟结果还提供了有力证据，表明此类团簇的主要碎裂通道涉及中性(LiHCOO)₂二聚体。