Scattering of neutral NH3 clusters off LiF(100): angular distributions of NH3 and small clusters

Abstract

The scattering behavior of neutral ammonia clusters off a LiF(100) surface is studied. Ammonia clusters are produced by a coexpansion of NH and Kr with an average kinetic energy of 48 meV per monomer molecule. Using single photon VUV laser ionization at "118 nm (h "10.49 eV) the mass distribution of scattered particles is obtained in a reflecting time-of-flight mass spectrometer. Compared with the incoming cluster beam the average cluster size of the scattered particles is drastically decreased. The angular distribution of NH> and NH> after scattering reveals a strong inelastic interaction between the clusters and the LiF(100) surface which is described in the context of a thermokinetic model and a phonon excitation along the (001) azimuth of the LiF(100) surface.

Cluster Impact Chemistry

“…Using SIMION 112 trajectory simulations, we verified that all ions leaving the target with a kinetic energy of less than 100 eV parallel to the target surface can be collected. This feature is highly relevant for two reasons: First, it is known from theory [113][114][115][116] and experiment 3,10,16,25 that clusters scatter into large angles with respect to the surface normal and thus can escape collection and detection. Second, it allows us to investigate the important lowenergy range of collision energies down to 1 eV without significant loss in ion transmission.…”

“…While cluster science has grown to a well-established field during the last decades, recently a new and potentially useful area has emerged, i.e., the investigation of phenomena involving the interaction of clusters with solid surfaces. Experimental results for the scattering of atomic and molecular clusters from solid surfaces have been reported for neutral − and ionic − clusters, as well as secondary electron emission due to the impact of clusters, ,− …”

Water Cluster Collisions with Graphite Surfaces: Angular-Resolved Emission of Large Cluster Ions

“…When the collision energy is comparable to the binding energy of the cluster, the surface collision results in processes such as cluster fragmentation and scattering of surviving cluster fragments. In this energy regime collisions of van der Waals clusters with surfaces have been studied experimentally using neutral cluster beam techniques [1][2][3][4][5][6][7][8] and theoretically by molecular dynamics simulations. [9][10][11][12][13][14][15][16] The behavior of hydrogen-bonded clusters under similar conditions has also been investigated experimentally [17][18][19][20][21][22] and theoretically.…”

“…When the collision energy is comparable to the binding energy of the cluster, the surface collision results in processes such as cluster fragmentation and scattering of surviving cluster fragments. In this energy regime collisions of van der Waals clusters with surfaces have been studied experimentally using neutral cluster beam techniques − and theoretically by molecular dynamics simula-tions. − The behavior of hydrogen-bonded clusters under similar conditions has also been investigated experimentally − and theoretically. , For higher collision energies the rapid compression of the cluster at impact may provide extreme conditions of high density and temperature, − and classical trajectory calculations have been used to investigate chemical reactions that occur inside the cluster − or at the cluster−surface interface . The use of cluster ions in surface impact experiments allows for size selection and better control of the collision energy, and deposition, scattering, and dissociation of cluster ions have recently been studied. − Surface deposition of size-selected clusters is also being investigated for material processing applications, including the production of high-quality thin films. , …”

Energy Redistribution in I2-(CO2)n Collision on Silicon Surface

“…Impact of a cluster onto a solid surface has been investigated, with particular attention on impulsive and coherent interparticle collision occurring in the cluster. − One of the pioneering works is a computer simulation of (Ar) 561 collision events onto an NaCl(001) surface by Cleveland and Landman, who have predicted a local and temporal rise of energy and density in the colliding (Ar) 561 . At the collision energy of 2 eV per argon atom, the effective temperature and pressure reach as high as 4000 K and 10 GPa, respectively.…”