M. W. Newman

Light-emitting nanostructures formed by intense, ultrafast electronic excitation in silicon (100)

The intense, ultrafast electronic excitation of clean silicon (100)–(2×1) surfaces leads to the formation of silicon nanostructures embedded in silicon, which photoluminescence at ∼560 nm wavelength (∼2 eV band gap). The silicon surfaces were irradiated with slow, highly charged ions (e.g., Xe44+ and Au53+) to produce the electronic excitation. The observation of excitonic features in the luminescence is particularly unusual for silicon nanostructures. The temperature dependence and the measurement of the triplet–singlet splitting of the emission strongly support the excitonic assignment.

Influence of hydrogen on the stability of positively charged silicon dioxide clusters

Spectra of positively charged secondary ions from thermally grown SiO2 films were recorded in a time-of-flight secondary ion mass spectrometry scheme. Ablation of cluster ions was induced by the impact of slow (4 keV/u) Au69+ projectiles. The intensities of SixOyHz+, (x=1–22, y=1–44, z=0–7) clusters are found to depend sensitively on the oxygen to silicon ratio and also on the hydrogen content. We find that oxygen rich clusters, y=2x+1, and, in one case, y=2x+2, can be stabilized by the incorporation of two additional hydrogen atoms in the cluster.

Electronic sputtering of solids by slow, highly charged ions: Fundamentals and applications

Electronic sputtering in the interaction of slow (v < vBohr), highly charged ions (SHCI) with solid surfaces has been subject of controversial discussions for almost 20 years. We review results from recent studies of total sputtering yields and discuss distinct microscopic mechanisms (such as defect mediated desorption, Coulomb explosions and eAects of intense electronic excitation) in the response of insulators and semiconductors to the impact of SHCI. We then describe an application of ions like Xe 44a and Au 69a as projectiles in time-of-flight secondary ion mass spectrometry for surface characterization of semiconductors. ” 2000 Elsevier Science B.V. All rights reserved.

The effects of radiation on (1,3,5 - triamino - 2,4,6 - trinitrobenzene) TATB studied by time-of-flight secondary ion mass spectrometry

Abstract Highly Charged Ion (HCI) Time-of-Flight (TOF) Secondary Ion Mass Spectrometry (SIMS) has been employed to analyze the changes in the surface composition of TATB caused by low energy electron, ultraviolet, and Gamma ray irradiation. Comparisons are made between canary yellow (not irradiated) TATB and TATB that has been “greened” by exposure to radiation. We ascribe the color change from yellow to green to a loss of oxygen. Another striking aspect of this study is the presence of a feature at m/z = 30 (NO+) for highly charged ion SIMS, which does not occur in singly charged ion TOF SIMS.