Temperature Effects of Sputtering of Langmuir-Blodgett Multilayers.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) and atomic force microscopy (AFM) are employed to characterize a wedge-shaped crater eroded by a 40 keV C(60) (+) cluster ion beam on an organic thin film of 402 nm of barium arachidate (AA) multilayers prepared by the Langmuir-Blodgett (LB) technique. Sample cooling to 90 K was used to help reduce chemical damage, improve depth resolution and maintain constant erosion rate during depth profiling. The film was characterized at 90 K, 135 K, 165 K, 205 K, 265 K and 300 K.

An experimental and theoretical view of energetic C cluster bombardment onto molecular solids.

Recent experimental measurements and calculations performed by molecular dynamics computer simulations indicate, for highly energetic C primary ions bombarding molecular solids, the emission of intact molecules is unique. An energy- and angle-resolved neutral mass spectrometer coupled with laser photoionization techniques was used to measure the polar angle distribution of neutral benzo[a]pyrene molecules desorbed by 20-keV [Formula: see text] primary ions and observed to peak at off-normal angles integrated over all possible emission energies. Similarly, computer simulations of 20-keV C projectiles bombarding a coarse-grained benzene system resulted in calculations of nearly identical polar angle distributions.

Cluster secondary ion mass spectrometry and the temperature dependence of molecular depth profiles.

The quality of molecular depth profiles created by erosion of organic materials by cluster ion beams exhibits a strong dependence upon temperature. To elucidate the fundamental nature of this dependence, we employ the Irganox 3114/1010 organic delta-layer reference material as a model system. This delta-layer system is interrogated using a 40 keV C(60)(+) primary ion beam.

Fluid Flow and Effusive Desorption: Dominant Mechanisms of Energy Dissipation after Energetic Cluster Bombardment of Molecular Solids.

The angular distribution of intact organic molecules desorbed by energetic C(60) primary ions was probed both experimentally and with molecular dynamics computer simulations. For benzo[a]pyrene, the angular distribution of intact molecules is observed to peak at off-normal angles. Molecular dynamics computer simulations on a similar system show the mechanism of desorption involves fast deposition of energy followed by fluid-flow and effusive-type emission of intact molecules.