Effects of electron kinetic energy and ion-electron inelastic collisions in electron capture dissociation measured using ion nanocalorimetry.
Effects of electron kinetic energy and ion-electron inelastic collisions in electron capture dissociation measured using ion nanocalorimetry.
复制标题
使用离子纳量热法测量电子捕获解离中电子动能和离子-电子非弹性碰撞的影响。
DOI：
10.1016/j.jasms.2008.02.010
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发表时间：
2008
影响因子：
3.2
通讯作者：
Williams,EvanR
中科院分区：
文献类型：
--
作者：
O'Brien,JeremyT;Prell,JamesS;Holm,AnneIS;Williams,EvanR
离子纳米量热法用于测量电子捕获解离（ECD）中电子动能的影响。利用离子纳米量热法，在活化时沉积到水合簇中的内能可以从蒸发的水分子的数量来确定。在ECD过程中，将加热的阴极电位从−1.3 V变化到−2.0 V，对[Ca（H2O）15]2+或[Ca（H2O）32]2+还原簇中损失的水分子的平均数量没有影响，即使这些数据外推到零伏的阴极电位。这些结果表明，在ECD时，这些离子中的初始电子动能没有转化为内能。电子辐照时间高达200 ms，没有观察到非弹性离子-电子碰撞的离子加热效应，尽管[Ca（H2O）17]2+在较长的辐照时间下会发生一些加热。相比之下，这种效应对于[Ca（H2O）32]2+是可以忽略的，[Ca（H2O）32]2+是纳米量热实验中通常使用的团簇尺寸，这表明与这些较大团簇的辐射吸收和发射的效应相比，来自非弹性离子-电子碰撞的能量转移是可以忽略的。这些结果具有重要意义，建立准确的电化学氧化还原电位，在气相中使用离子纳米量热法的绝对基础上测量，可以与在溶液中测量的相对电位。
Ion nanocalorimetry is used to measure the effects of electron kinetic energy in electron capture dissociation (ECD). With ion nanocalorimetry, the internal energy deposited into a hydrated cluster upon activation can be determined from the number of water molecules that evaporate. Varying the heated cathode potential from −1.3 to −2.0 V during ECD has no effect on the average number of water molecules lost from the reduced clusters of either [Ca(H2O)15]2+or [Ca(H2O)32]2+, even when these data are extrapolated to a cathode potential of zero volts. These results indicate that the initial electron kinetic energy does not go into internal energy in these ions upon ECD. No effects of ion heating from inelastic ion-electron collisions are observed for electron irradiation times up to 200 ms, although some heating occurs for [Ca(H2O)17]2+at longer irradiation times. In contrast, this effect is negligible for [Ca(H2O)32]2+, a cluster size typically used in nanocalorimetry experiments, indicating that energy transfer from inelastic ion-electron collisions is negligible compared with effects of radiative absorption and emission for these larger clusters. These results have significance toward establishing the accuracy with which electrochemical redox potentials, measured on an absolute basis in the gas phase using ion nanocalorimetry, can be related to relative potentials measured in solution.