(1976). Nuclear Tracks in Solids (Principles and Applications) Nuclear Technology: Vol. 30, No. 1, pp. 91-92.

Nuclear Tracks in Solids (Principles and Applications)

Latent nuclear tracks are damaged zones, created along the paths of rapidly moving ions in solids. They are stored indefinitely in many insulators and can be used to initiate a phase separation process by one of several procedures that remove, collect, or transform material along the latent track. The resulting two-step technique is based on separate inscription and development stages, similar to the lithographic techniques using visible light, uv, x rays, or electrons. In contrast to these other techniques, however, it is applicable even to mechanically very stable, chemically inert, radiation-resistant dielectric materials. The most common development procedure is track etching, which acts as a chemical "amplifier" that dissolves the damaged zone of the latent track preferentially, creating etch pits or channels that can be extremely fine. Etched track diameters start around 10 nm and increase linearly with the etching time. The most outstanding feature of the technique is that one single particle is sufficient to create a developable damage. This unique combination of recording and revealing properties makes possible a single-particle structuring tool with a very wide array of applications. With the advent of high-energy, heavy-ion accelerators, with ion ranges between micrometers and centimeters, large-scale application of the technique to the imprinting of structure onto solids has become possible. At present, most frequently random track arrays are employed to induce global property changes of the solid volume or surface. In the future, scanning ion microbeam technology will make possible local generation of oriented track structures with high precision. This "ultimate" microtool should provide the versatility of a computer-controlled mechanical lathe. This review describes the processes involved in track generation. It outlines applications that are on the verge of being commercialized at present and considers future possibilities.

Production and use of nuclear tracks: imprinting structure on solids

Objective— The involvement of transition metals in atherosclerosis is controversial. Some epidemiological studies have reported a relationship between iron (Fe) and cardiovascular disease, whereas others have not. Experimental studies have reported elevated levels of iron and copper (Cu) in diseased human arteries but have often used methods that release metal ions from proteins. Methods and Results— In this study, we have used the minimally invasive technique of electron paramagnetic resonance (EPR) spectroscopy and inductively coupled plasma mass spectroscopy (ICPMS) to quantify iron and copper in ex vivo healthy human arteries and carotid lesions. The EPR spectra detected are characteristic of nonheme Fe(III) complexes. Statistically elevated levels of iron were detected in the intima of lesions compared with healthy controls (0.370 versus 0.022 nmol/mg tissue for EPR, 0.525 versus 0.168 nmol/mg tissue by ICPMS, P<0.05 in each cases). Elevated levels of copper were also detected (7.51 versus 2.01 pmol/...

Direct Detection and Quantification of Transition Metal Ions in Human Atherosclerotic Plaques: Evidence for the Presence of Elevated Levels of Iron and Copper

Small metallic particles with diameters in the range 1–100 nm have interesting properties which can sometimes be very different from those of bulk metals. Such colloidal particles play an important part in fields which range from catalysis to radiation damage in compound solids, and also have an intrinsic interest since in some respects they can be regarded as a state of matter intermediate between that of a molecule and a solid. In ionic crystals colloids can be produced either by irradiation or by the introduction of a stoichiometric excess of the metal constituent. In either case the colloids form as a result of the aggregation of fundamental point defects, but it is only fairly recently that a reasonably coherent picture of these processes has emerged and the properties of the colloids have been related to those of small metallic particles studied for other reasons. This review discusses the progress which has been made through the use of a large number of different techniques to study the pr...

Metal colloids in ionic crystals

The measurement techniques of beam-foil spectroscopy are reviewed. These comprise the study of wavelengths of heavy ions with low and high charge states at visible, UV and X-ray wavelengths from normal excited states, multiply excited states and high-n Rydberg levels; the measurements of mean lifetimes above 10-12 s and metastable states up to 100 ns; high-resolution Auger electron measurements; and the application of atomic alignment and orientation by both perpendicular and tilted foils to measurements of atomic structures and analysis of the beam-foil excitation process. A theoretical description of the emission of light from anisotropically excited systems is included. Associated techniques of time-resolved spectroscopy are compared.

https://iopscience.iop.org/article/10.1088/0034-4885/40/2/002/pdf

Beam-foil spectroscopy

In the electron energy spectra used to determine life-times of the metastable three electron (ls 2s 2p) 4P5/2-state in nitrogen, oxygen, and neon a triple peak structure is observed. The peak with the highest transition energy corresponds to the decay of the 4P5/2-state. A second transition is attributed to the decay of the (Is 2s2) 2S1/2-state. The relatively long life-time of this non-metastable state may be due to cascading effects.

/pdf/low-energy-metastable-autoionizing-states-in-nitrogen-oxygen-rr6pn7q8rp.pdf

Low-energy metastable autoionizing states in nitrogen, oxygen, and neon (*)

The projectile energy dependence of the cross sections for electron capture and for electron loss to the continuum states of the projectiles (ECC and ELC) in 50-150 keV amu-1 He+-He,Ar collisions has been studied measuring the spectra of forward ejected 'cusp' electrons in coincidence with the scattered He+ and He2+ projectiles at five different impact energies. The contribution of the ECC to the forward electron cusp has been found to increase with decreasing projectile energy dominating the forward electron cusp production at 50 keV amu-1 collision energies.

The contribution of the ECC to the forward electron cusp in 50-150 keV amu-1 He+-He,Ar collisions

Kinetic emission of secondary electrons (SE) in high-energy ion-solid collisions is strongly correlated to the strength and gradient of the electronic stopping power of the projectile at the entrance and the exit surfaces of the solid. We have measured the total, forward, and backward SE yields of S{sup {ital q}+} (3.9 MeV/u) and C{sup {ital q}+} (1 MeV/u) passing through carbon foils as a function of the initial charge state {ital q} (S, 10--16; C, 2--6) and of the target thickness {rho}{ital x} (3--180 {mu}g/cm{sup 2}). The strong increase of the total and backward SE yields with {ital q} is discussed in the framework of preequilibrium stopping and effective charge of the projectile ion at the entrance of the solid surface. It reveals shell effects of structured projectiles.

Secondary-electron yield as a probe of preequilibrium stopping power of heavy ions colliding with solids

The foil-excitation method has been employed to determine lifetimes, transition probabilities, and f values for deltan = 0 dipole transitions between the n = 2 states of the highly stripped ions, S/sup 12 +/ and S/sup 13 +/ The fine structure interval between the J = 1/2 and 3/2 levels of the 1s/sup 2/2p /sup 2/P/sup o/ term in S/sup 13 +/ was also determined, and the result confirms recent astrophysical observations

K. O. Groeneveld

Papers

Low-energy metastable autoionizing states in nitrogen, oxygen, and neon (*)

The contribution of the ECC to the forward electron cusp in 50-150 keV amu-1 He+-He,Ar collisions

Secondary-electron yield as a probe of preequilibrium stopping power of heavy ions colliding with solids

Oscillator strengths for in-shell (. delta. n = 0) dipole transitions in Li- and Be-like sulfur

Ion induced electron ejection from solids