Carbon K-edge X-ray absorption near edge structure (XANES) spectra of evaporated films of poly-p-phenylenes and polyacenes were measured by use of synchrotron radiation. Only one dominant resonance associated with a Cls-to-x* transition was observed for each poly-p-phenylene, although there should exist several x* unoccupied orbitals which are energetically well separated from each other. These features were characterized by means of semi-empirical molecular orbital (MO) calculations based on the equivalent core approximation, which leads to a satisfactory agreement between the observed and calculated spectra. The calculations show that the x* orbitals, which are delocalized in the ground state, become localized by the creation of a CIS core hole. Spectral features of polyacenes, which are somewhat different from those of poly-p-phenylenes in their x* regions, indicate a lesser degree of I[* localization.

Polarization dependent XANES spectra were obtained by use of synchrotron radiation for oriented polyethylene and fluorinated polyethylenes: (1) elongated polyethylene (PE) film, (2) elongated poly(viny1idene fluoride) (PVDF) film, (3) poly(tetrafluoroethy1ene) (PTFE) film, (4) oriented evaporated film of hexatriacontane. CH3(CH,),,CH, as a model compound of PE, (5) oriented evaporated film of perfluoroeicosane, CF,(CF,),,CF, as a model compound of PTFE.Pronounced polarization dependence was observed for each compound, which allows unambiguous assignments of the XANES spectrum. Fluorination effects on the XANES spectra was also discussed

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The change of electronic structure at UV photopolymerization was studied by XANES and UPS for evaporated films of a long-chain diacetylene compound tricosa-10, 12-diynoic acid. The UPS spectra showed a large lowering of ionization threshold energy (from 7.0eV to ca. 5.2eV) due to the formation of a conjugated n electron system, as in our previous study of Langmuir-Blodgett films. The XANES spectra showed that the alkyl chains are inclined to the substrate surface, consistent with X-ray diffraction studies. The CIS + n* absorption showed a drastic change on photopolymerization, which could be well explained with CNDOjS molecular orbital calculations taking account of the hole formation using the equivalent-core approximation. From XANES studies, no essential discontinuity was found between the blue and red forms of the polymers formed.

The near-edge X-ray absorption fine structure (NEXAFS) spectra were studied at the S K-edge using synchrotron radiation for various sulfur-containing organic photographic materials in the solid state and in the adsorbed states on AgCl and AgBr grains. The features in the spectra of neat solids were assigned by mutual comparison and polarization dependence. The spectra of merocyanine dyes containing thiocarbonyl group were drastically affected by the adsorption on AgCl and AgBr, with significant suppression of the peak corresponding to the excitation of the S 1s electron into the π* orbital at the SC bond. This change is interpreted as indicative that these compounds are adsorbed at the S atom in the thiocarbonyl group, such rearrangement of the chemical bonds leading to a contribution from the zwitterionic form with S-−CN+< structure. By taking account of the area occupied by a molecule estimated from the measurements of the adsorption isotherm, a rather detailed picture emerged about the adsorbed state of this kind of dye. In contrast, the spectra of merocyanine and cyanine dyes containing sulfur in the five-membered aromatic ring showed little change by the adsorption on AgCl, indicating that the S atom is not the adsorption site or that the interaction between the molecule and AgCl is weak.

T h i s paper p r e s e n t s a review of experiments on t h e production and h e a t i n g of c u r r e n t l e s s plasmas by e l e c t r o n c y c l o t r o n ( E C ) waves i n t h e Heliotron-E, Wendelstein V I I -A , and L-2 s t e l l a r a t o r s , i n wide ranges of t h e magnetic f i e l d (1.0 -2.5 T ) , frequency (28 -70 GHz) and microwave power (100 -500 kW). EC h e a t i n g of low and high-densit,y c u r r e n t l e s s plasmas as well a s of ohmically heated (OH) plasmas i s d i s c u s s e d . Nonlinear i o n h e a t i n g and plasma c u r r e n t g e n e r a t i o n were observed t o accompany EC plasma h e a t i n g . It was found t h a t a high e f f i c i e n c y of microwave a b s o r p t i o n , a high e l e c t r o n temperature ( 1 -1.5 keV) and a c o n s i d e r a b l e energy confinement, t,ime a r e c h a r a c t e r i s t i c of EC plasma h e a t i n g .

Various carbon thin films synthesized by the hot filament chemical vapor deposition (CVD) method with various methane concentrations in hydrogen (1.0-12.5 vol.%) and temperatures of Si substrate (770-1000°C) were characterized by X-ray-absorption near-edge structure (XANES) and Raman spectroscopies as well as by scanning electron microscopy (SEM) and X-ray diffraction. Based on these results, the structural change of carbon thin films is deduced as a function of methane concentration and substrate temperature. Comparison between the Raman and XANES spectra demonstrates the usefulness of XANES spectroscopy for the characterization of carbon thin films and the complementary character between these spectroscopies.