Below is a short discussion of what has been done computationally on cluster impact
phenomenon. It needs to be rearranged/rewritten if we decide to incorporate this into the
proposal.
Molecular dynamics technique has been successfully applied to study cluster-surface
collisions for a range of cluster and surface materials and cluster energies (Refs. 1,2,3,4,5
are just a few examples out of numerous computational studies). The focus of the most
simulations, however, has been on the processes induced in the target (surface
modification, implantation, phase transitions) [1,2,4], film growth [3], sputtering of the
target material [1,2,4], or desorption of the surface adlayer [5]. The number of atoms or
molecules in the clusters typically varies from a few to several thousands.
In a few studies, that are closer related to the proposed work, the collision-induced
disintegration of molecular clusters and the parameters of the disintegration products has
been addressed
[6,7,8,9,10,11,12,13,14,15,16,17].
Cleveland and Landman [6]
performed calculations for 561-atomic cluster impacting on sodium chloride surface with
a velocity of 3000 m/s and discussed the results in terms of shock wave phenomenon
similar to continuum analysis by Mahoney et al. []. Similar phenomenon was observed
for clusters of up to 555 inert gas atoms scattered from a Pt surface by Even et al. [7] and
Schek and Jortner [16]. Svanberg, Marković, and Pettersson studied fragmentation of
larger, up to 4400 atoms, inert gas clusters for impact velocities of 50-300 m/s [6], 100700 m/s [7] and …[10] and different temperatures of Pt(111) surface [9,10]. It has been
discussed that at high incident velocities the formation of intra-clusteral shock wave
dominates the fragmentation and leads to the efficient non-thermal ejection of fast
particles parallel to the surface [6,7,10,14]. Levine et al. performed simulations for
smaller inert gas [11,12] and molecular clusters [13,15] and studied collision-induced
chemical reactions [13,14]. Recently, MD simulation of collision between a water cluster
composed of 4094 molecules and a graphite surface was simulated for the incident
velocity of 470 m/s [17]. Although the simulations listed above are not directly
applicable to the analysis of IDEC, they demonstrate the ability of MD simulation
technique to provide microscopic insight into the complex processes occurring under the
high velocity cluster impact.
In the present work much larger clusters (hundreds of thousands molecules) will be
considered and simulations will be performed under conditions directly relevant to IDEC
experiments. The focus of the proposed computational work will be on the mechanisms
of cluster disintegration, ejection of secondary clusters and molecules, survivability and
desolvation of analyte molecules... – this need to be changed.
Ref. 18
[1] M. H. Shapiro and T. A. Tombrello, Simulation of sputtering induced by high energy gold clusters,
Nucl. Instrum. Methods Phys. Res. B 152, 221 (1999)
[2] H.-P. Cheng, Cluster-surface collisions: Characteristics of Xe55- and C20–Si[111] surface
bombardment, J. Chem. Phys. 111, 7583 (1999).
[3] L. F. Qi, S. B. Sinnott, Generation of 3D hydrocarbon thin films via organic molecular cluster
collisions, Surf. Sci. 398, 195 (1998).
[4] R. Aderjan and H. M. Urbassek, Molecular-dynamics study of craters formed by energetic Cu cluster
impact on Cu, Nucl. Instrum. Methods Phys. Res. B 164-165, 697 (2000).
[5] T. C. Nguyen, D. W. Ward, J. A. Townes, A. K. White, K. D. Krantzman, and B. J. Garrison, A
theoretical investigation of the yield-to-damage enhancement with polyatomic projectiles in organic
SIMS, J. Phys. Chem. B 104, 8221 (2000).
[6] C. L. Cleveland and U. Landman, Dynamics of Cluster-Surface Collisions, Science 257, 297 (1991).
[7] U. Even, I. Schek, and J. Jortner, Chem. Phys. Lett. 202, 303 (1993).
[8] N. Marković and J. B. C. Pettersson, Evaporation model of cluster scattering from surfaces, J. Chem.
Phys. 100, 3911 (1994).
[9] M. Svanberg and J. B. C. Pettersson, Survival of noble gas clusters scattering from hot metal surfaces,
Chem. Phys. Lett. 263, 661 (1996).
[10] M. Svanberg, N. Marković, and J. B. C. Pettersson, Chem. Phys. 220, 137 (1997).
[11] T. Raz, U. Even, and R. D. Levine, Fragment size distribution in cluster impact: Shattering versus
evaporation by a statistical approach, J. Chem. Phys. 103, 5394 (1995).
[12] T. Raz and R. D. Levine, On the shattering of clusters by surface impact heating, J. Chem. Phys. 105,
8097 (1996).
[13] H. Kornweitz, T. Raz, and R. D. Levine, Driving high threshold chemical reactions by cluster-surface
collisions: molecular dynamics simulations for CH3I clusters, J. Phys. Chem. A 103, 10179 (1999).
[14] I. Schek, J. Jortner, T. Raz, R. D. Levine, Cluster-surface impact dissociation of halogen molecules in
large inert gas clusters, Chem. Phys. Lett. 257, 273 (1996).
[15] W. Christen, U. Even, T. Raz, and R. D. Levine, The transition from recoil to shattering in clustersurface impact: an experimental and computational study, Int. J. Mass Spectrom. 174, 35 (1998).
[16] I. Schek and J. Jortner, Microshock wave propagation in molecular clusters, J. Chem. Phys. 104, 4337
(1996).
[17] A. Tomasic, N. Marković, and J. B. C. Pettersson, Direct scattering and trapping-desorption of large
water clusters from graphite, Chem. Phys. Lett. 329, 200 (2000).
[18] P. U. Andersson and J. B. C. Pettersson, Water cluster collisions with graphite surfaces: angularresolved emission of large cluster ions, J. Phys. Chem. B 102, 7428 (1998).