Electron irradiation high-resolution

High-resolution transmission electron microscopy (HREM) is the technique best suited for the structural characterization of nanometer-sized graphitic particles. In-situ processing of fullerene-related structures may be performed, and it has been shown that carbonaceous materials transform themselves into quasi-spherical onion-like graphitic particles under the effect of intense electron irradiation[l 1],... 

Fig. I. High-resolution electron micrographs of graphitic particles (a) as obtained from the electric arc-deposit, they display a well-defined faceted structure and a large inner hollow space, (b) the same particles after being subjected to intense electron irradiation (note the remarkable spherical shape and the disappearance of the central empty space) dark lines represent graphitic layers.

A light-ion microbeam system connected with the 3-MV single-ended accelerator was developed for high-resolution ion beam microanalysis [37]. The highest spatial resolution of 0.25 pm was achieved for 2-MeV proton and helium ions. The beam spot size was estimated from the intensity distribution of the secondary electrons emitted from a silicon relief pattern irradiated with the 2-MeV helium ion microbeam as shown in Fig. 10. 

The incorporation of small percentages (<10%) of 3-oximino-2-butanone methacrylate (4) into poly(methyl methacrylate) (PMMA) (Scheme I) results in a four fold increase in polymer sensitivity in the range of 230-260 nm flO.l 11. Presumably, the moderately labile N-O bond is induced to cleave, leading to decarboxylation and main chain scission (Scheme II). The sensitivity is further enhanced by the addition of external sensitizers. Also, preliminary results indicated that terpolymerization with methacrylonitrile would effect an additional increase. These results complement those of Stillwagon (12) who had previously shown that copolymerization of methyl methacrylate with methacrylonitrile increased the polymer s sensitivity to electron beam irradiation. The mole fraction of the comonomers was kept low in order to insure retention of the high resolution properties of PMMA (3.41. 

Recently chloromethylated polystyrene (CMS), a highly sensitive, high resolution electron resist with excellent dry etching durability, was developed. Very recently reactive intermediates in irradiated polystyrene, which is a starting material of CMS, have been studied and the transient absorption spectra of excimer (2-4), triplet states (2,5), charge-transfer complexes, and radical cations (6) of polystyrene have been measured. The present paper describes the cross-linking mechanism of the high sensitivity CMS resist and compares it to that of polystyrene on the basis of data on reactive intermediates of polystyrene and CMS. 

X-Ray Photoelectron Spectroscopy. During the 1960s, Kai Sieg-bahn and co-workers (12) developed a surface-sensitive, high-resolution photoelectron spectroscopy that used x-rays as the irradiation source. He designated it as Electron Spectroscopy for Chemical Analysis or ESCA. The generic denotation for x-ray photoelectron spectroscopy of XPS is more accurate than ESCA and is preferred for clarity and for indicating the relationship of UPS. 

EPR spectroscopy is used widely in the study of proteins and of lipid-protein interactions.0 It has often been used to estimate distances between spin labels and bound paramagnetic metal ions.g A high-resolution EPR technique that detects NMR transitions by a simultaneously irradiated EPR transition is known as electron-nuclear double resonance (ENDOR).h... 

The reduction of transition-metal species under the intense electron irradiation of the high-resolution electron microscope used in [37] additionally represents a process that could also lead to Sc-L2>3 data deviating from those presented here, which were measured with the gentle method of soft x-ray absorption. 

Systematic investigations of the laser-cluster interaction were carried out by simultaneously measuring high-resolution X-ray emission spectra and ion energy spectra produced by the laser irradiation of micron-sized Ar clusters at laser intensities of 1018 to 1019 W/cm2. To suppress the creation of preplasma, we designed a special conical nozzle and eliminated the laser prepulse. The results indicate that the explosion time scale for micron-sized clusters is much longer than that for nanometer-sized clusters. It is found that hot electrons produced by a higher contrast pulse (a smaller prepulse) allow the isochoric... 

Poly(methylmethacrylate), (PMMA), is one resist which is especially favored by researchers due to its high resolution and contrast. Linewidths as small as 100 A have been produced with an extremely high dose of x-rays (10 J/cm ) using PMMA. However, even PMMA s normal sensitivity of 600-1000 mJ/cnr is too slow for commercial use. There have been many attempts to improve the sensitivity of PMMA to electron beam irradiation mainly by copolymerization (8). In the current paper, we describe an alternative approach whereby a sensitive polymer is physically blended with PMMA to increase its sensitivity and yet maintain the good film qualities associated with PMMA as a positive x-ray resist. 

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