Plasma, X-ray source

Fig. 3.1. Left visible pump/X-ray probe scheme for femtosecond TRXRD experiments. Hard X-ray pulses are generated by shining intense femtosecond laser pulses on a metal target (laser plasma X-ray source). Right geometrical structure factor of bismuth as a function of inter-atomic distance for diffraction from (111) and (222) lattice planes. From [1] and [2]...

Ultrashort laser-plasma X-ray sources based upon the Ka emission process have been exploited since about 10 years ago to study some dynamical effects in simple systems, typically involving atomic motion, occurring on the timescale of 100fs. A complete review of such effects, in particular in... 

Resist Design and Preparation. Our objectives were to develop new resist materials which would be compatible with first generation (electron impact) and second generation (plasma) x-ray sources. 

C.L. Gordon III, G.Y. Yin, B.E. Lemoff, P.E. Bell, G.P.J. Barty Timegated imaging with an ultrashort-pulse laser-produced-plasma X-ray source. Opt. Lett. 20, 1056 (1995)... 

C. Tillman, G. Grafstrom, A.-Ch. Jonsson, B.-A. Jdnsson, I. Mercer, S. Mattson, S.-E. Strandh, S. Svanberg Survival of mammalian cells exposed to ultrahigh dose rates from a laser-produced plasma X-ray source. Radiology 213, 860 (1999)... 

A completely different emission process, which can in principle provide table-top ultrashort X-ray sources up to 100 keV has been recently discovered and studied, both from an experimental and a theoretical viewpoint [9]. It can be understood as one consider that the electrons, trapped and accelerated in a plasma wake as described earlier, can also experience, in some cases, a transverse force pulling them toward the beam axis. This force is basically due to the creation of a sort of plasma channel at low electron density, which is a consequence of the ponderomotive force that expels the electrons from the laser beam axis (the ions, due to their larger inertia, being fixed). The trapped electrons thus undergo a sort of wiggler motion, thus producing so-called betatron radiation. 

X-ray photoelectron spectroscopy (XPS) was used for elemental analysis of plasma-deposited polymer films. The photoelectron spectrometer (Physical Electronics, Model 548) was used with an X-ray source of Mg Ka (1253.6 eV). Fourier transform infrared (FTIR) spectra of plasma polymers deposited on the steel substrate were recorded on a Perkin-Elmer Model 1750 spectrophotometer using the attenuated total reflection (ATR) technique. The silane plasma-deposited steel sample was cut to match precisely the surface of the reflection element, which was a high refractive index KRS-5 crystal. 

Rousse A, Audbert P, Geindre JP, Fallies F, Gauthier JC, Mysyrowicz A, Grillon G, Antonetti A (1994) Efficient Ka X-ray source from femtosecond laser-produced plasmas. Phys Rev E 50 2200-2207... 

Aside from the first instant of the interaction of the laser with the matter, the X-ray radiation self-emitted from laser-produced plasmas provides an efficient diagnostic of processes that occur within such plasmas. Over the past ten years, the advent of short-duration laser systems and the progress made in the development of short-pulse X-ray sources have led to such systems being applied to multidisciplinary fields in order to probe matter. 

Fig. 11.1. Principle of the nonlinear Thomson scattering X-ray source. The nonlinear motion of the free plasma electrons oscillating in the strong electromagnetic laser held (ao) produces high harmonics of the fundamental laser light that can reach the X-ray spectral range. As ao is increased, the radiation becomes more collimated...

Fukuda Y, Akahane Y, Aoyama M, Inoue N, Ueda H, Nakai Y, Tsuji K, Yamakawa K, Hironaka Y, Kishimura H, Morishita H, Kondo K, Nakamura KG (2004b) Relativistic laser plasma from micron-sized argon clusters as a debris-free X-ray source for pulse X-ray diffraction. Appl. Phys. Lett. 85 5099-5101... 

Electron spectroscopy for chemical analyses (ESCA) spectra were obtained on a Varian spectrometer Model VIEE-15 with a MgK x-ray source. Analyses were obtained on samples before and after plasma irradiations. Spectra represent electron binding energies (Ejje) in eV. 

ICP analyses were performed by Plasma Absorption Emission Spectroscopy (ICP-AES). BET surface areas were measured with a Micromeritics TriStar 3000 instrument after degassing the samples at 150 C under a 0.13 Pa vacuum overnight. XPS analyses were performed on a SSI X-probe spectrometer (SSX-100/206 photoelectron spectrometer Fisons) equipped with a monochromatized microfocused Al Ka X-ray source (1486.6 eV) and a hemispherical analyser. The binding energies were calculated relative to the C-(C, H) component of the adventitious Cls carbon peak fixed at 284.8 eV. Zeta potential measurements were carried out in a PENKEM Zeta Meter 500, using 25 mg of sample ultrasonically dispersed in 200 ml of an aqueous solution... 

Wallis, G. 1982. Laser-generated plasmas as x-ray sources in the keV-range. Beitr. Plasmaphys. 22(4) 295-324. 

The surface elemental compositions of both the sulfur dioxide and allyl phenyl sulfone plasma treated samples were analyzed by a Perkin-Elmer PHI 5400 ESCA System with its packaged XPS software. The x-ray source was generated with an Mg anode energized at 15 kV and 300 W. The distance between the sample surface and the tip of the x-ray source anode was maintained constant at about 1.5 in. The aperture of the spherical capacitor electron energy analyzer was set at a diameter of 4 mm so that the area of the sample surface to be analyzed was about 1.3 mm in diameter. Both XPS survey and multiplex spectra of the plasma treated LDPE were collected at takeoff angles (0) of 10°, 30°, 45° and 75° with respect to the spherical capacitor electron energy analyzer, Angle-... 

B. Wellegehausen, M. Hube, F. Jim Investigation on laser plasma soft X-ray sources generated with low-energy laser systems. Appl. Rhys. B 49, 173 (1989)... 

The EXAFS experiment simply involves measuring the absorption spectrum in the vicinity of the absorption edge for the chosen element. This, of course, is easier said than done. A high-intensity, tunable X-ray source is required, and in practice almost aU experiments use synchrotron radiation, which gives useful spectra for solids, liquids or concentrated solutions in a few minutes. The K edges of elements down to about phosphorus or sulfur can be smdied by this method, and typically spectroscopy at the L edges is used for elements heavier than indium (Z = 49). For lighter elements, down to carbon, a laser-produced plasma can... 

The amount of deposited yttrium vs applied current densities was determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES). Concentration profiles were measured by secondary ion mass spectrometry (SIMS) on the coated samples before and after heat treatment, using a 10 keV primary ion source. The yttrium depth profiles were established with signals. The chemical state of the as-deposited and the thermally treated film was also investigated by X-ray photoelectron spectroscopy (XPS) using an Mg Ka X-ray source, without sputtering the surface. 

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