We present the data on ejection of molecules and emission of molecular ions caused by single impacts of 50 keV C₆₀²⁺ on a molecular layer of deuterated phenylalanine (D8Phe) deposited on free standing, 2-layer graphene. The projectile impacts on the graphene side stimulate the abundant ejection of intact molecules and the emission of molecular ions in the transmission direction. To gain insight into the mechanism of ejection, Molecular Dynamic simulations were performed. It was found that the projectile penetrates the thin layer of graphene, partially depositing the projectile’s kinetic energy, and molecules are ejected from the hot area around the hole that is made by the projectile. The yield, Y, of negative ions of deprotonated phenylalanine, (D8Phe-H)⁻, emitted in the transmission direction is 0.1 ions per projectile impact. To characterize the ejection and ionization of molecules, we have performed the experiments on emission of (D8Phe-H)⁻ from the surface of bulk D8Phe (Y = 0.13) and from the single molecular layer of D8Phe deposited on bulk pyrolytic graphite (Y = 0.15). We show that, despite the similar yields of molecular ions, the scenario of the energy deposition and ejection of molecules is different for the case of graphene due to the confined volume of projectile-analyte interaction. The projectile impact on the graphene-D8Phe sample stimulates the collective radial movement of analyte atoms, which compresses the D8Phe layer radially from the hole. At the same time, this compression bends and stretches the graphene membrane around the hole thus accumulating potential energy. The accumulated potential energy is transformed into the kinetic energy of correlated movement upward for membrane atoms, thus the membrane acts as a trampoline for the molecules. The ejected molecules are effectively ionized; the ionization probability is ∼30× higher compared to that obtained for the bulk D8Phe target. The proposed mechanism of ionization involves tunneling of electrons from the vibrationally excited area around the hole to the molecules. Another proposed mechanism is a direct proton transfer exchange, which is suitable for a bulk target: ions of molecular fragments (i.e., CN⁻) generated in the impact area interact with intact molecules from the rim of this area. There is a direct proton exchange process for the system D8Phe molecule + CN⁻.

中文翻译：

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通过keV簇离子从石墨烯和石墨中“蹦床”喷射有机分子

我们提出的数据是由50 keV C ₆₀ ²⁺对沉积在独立的2层石墨烯上的氘代苯丙氨酸（D8Phe）分子层的单次冲击所引起的分子喷射和分子离子发射的数据。在石墨烯侧的弹丸撞击刺激了完整分子的大量喷射以及分子离子在传输方向上的发射。为了深入了解喷射机理，进行了分子动力学模拟。已经发现，弹丸穿透了石墨烯的薄层，部分沉积了弹丸的动能，并且分子从由弹丸形成的孔周围的热区域射出。收量，ÿ，去质子化的苯丙氨酸的负离子，（D8Phe-H）^-，在发射方向发射的是每枚弹丸冲击0.1离子。为了表征分子的喷射和电离，我们进行了从本体D8Phe的表面（Y = 0.13）和沉积在本体热解石墨（Y上）的D8Phe单分子层发射（D8Phe-H）^-的实验。= 0.15）。我们表明，尽管分子离子的收率相近，但由于受射弹与分析物相互作用的空间有限，因此对于石墨烯来说，能量沉积和分子喷射的情况是不同的。弹丸对石墨烯-D8Phe样品的影响刺激了分析物原子的集体径向运动，这从孔中径向压缩了D8Phe层。同时，这种压缩使石墨烯膜在孔周围弯曲并拉伸，从而积累了势能。累积的势能转化为膜原子向上相关运动的动能，因此膜充当分子的蹦床。喷射出的分子被有效地电离；与大块D8Phe靶相比，电离几率高约30倍。提出的电离机理涉及电子从空穴周围的振动激发区到分子的隧穿。另一个提出的机制是直接质子转移交换，它适合于大量目标：分子碎片的离子（即CN在撞击区域产生的^-）与来自该区域边缘的完整分子相互作用。没有为系统D8Phe分子+ CN直接质子交换过程^- 。