Consistency of the Surface Roughness Determined from Soft-X-Ray Reflectance and Surface Profiles Measured Using a Scanning Tunnelling Microscope: Coherence Length of the Soft X-Rays

There exists serious inconsistency between the rms surface roughness determined from the Debye-Waller factor for the soft-x-ray reflectance analysis and that measured with an optical surface profiler. We have measured the surface profile of evaporated films using a scanning tunnelling microscope, and reproduce the profile with the Fourier components whose spatial wavelength is shorter than the coherence length of the incident soft x-rays in the reflectance measurement. The rms surface roughness derived from the high-pass filtered profile agrees well with that determined using the reflectance measurement. This result explains straightforwardly the photon-energy dependence of the surface roughness estimated by the soft-x-ray reflectance method.     

A NEW APPROACH TO THE OBSERVATION OF THE RESIST IN X-RAY CONTACT MICROSCOPY

X-ray microscopy is one of the useful applications of synchrotron radiation researches, and at present, X-ray contact microscopy is the best developed method in this field. The images on the resist in X-ray contact microscopy have been observed with a scanning electron microscope, and there have been some attempts to use the transmission electron microscope, but few have used the replica method. We have applied the replica method with plasma polymerization-film to observe X-ray images on the resist with a transmission electron microscope and found it to be applicable.
A long exposure time is required when we use the monochromatic synchrotron radiation with a grasshopper monochromator. Our preliminary experiments with a new light source, undulator radiation, showed that it is very intense and useful for X-ray contact microscopy.     

Chaperone activities of the 26S and 20S proteasome

The accumulation of misfolded or damaged proteins causes the failure of normal cell structure and functions necessary for growth and viability. To abort this adverse development, defective proteins must be rapidly repaired by molecular chaperones or destroyed by energy-dependent cytoplasmic proteases. A balance among these processes ultimately maintains cellular homeostasis. In eukaryotes, the 26S proteasome, a protease/chaperone complex, is a central component in the protein triage decision process. The 26S proteasome generally acts as a ubiquitination system, though it also selectively degrades structurally abnormal proteins in an ubiquitin-independent manner. In either case, all substrate proteins must undergo structural changes and stabilization necessary for their rapid degradation. It has, therefore, often been suggested that several chaperone functions are closely related to the stimulation of proteasomal degradation. This review summarizes recent discoveries pertaining to chaperone activities in the proteasomal degradation pathway, and to their regulation of protein breakdown mediated by the proteasome.     

Polarization Performance of a New Spectrometer Based on a Multilayer-Coated Laminar Grating in the 150-190-eV Region

We constructed a polarization spectrometer based on a laminar grating applied with a Mo/B₄C multilayer coating. The multilayer-coated grating had been previously evaluated to have high polarizance at around 6.7 nm (184 eV) due to the Brewster reflection. In this study the polarization spectrometer was found to be usable in a range from 150 to 190 eV. Using it, σ and π emission spectra in the B 1s emission from a CrB₂ single crystal were separately recorded for the first time in the soft x-ray region. The spectral feature of the emission was reasonably well reproduced by the band calculation.