SynopsisGas phase chemical modification (GCM) is found to be more preferable as a pretreatment for the XPS surface analysis of polymer materials than the conventional liquid phase treatment because it can circumvent problems such as solvent contamination and swelling. We have tried the quantification of the surface compcsition successfully by estimating the yield of the reaction from model samples. GCM was then applied to correlate the surface composition of NH, plasma-treated polystyrene films with their cell-affinity. The amount of primary-amine and that of carboxylic acid were directly determined by GCM. Although the amount of primary-amine, 15-20% of total nitrogen, did not depend on the treatment intensity, the total amine content for the treated samples increased with the plasma treatment intensity. The quantity of carboxylic acid generated was found to be very small. All treated samples had better cell-affinity than the control. The sample N2 (of medium treatment) showed the best cell-affinity. The most strongly treated sample N3, with larger amine content than N2, showed worse cell-affinity because of the interference by the sputtered SiO, on the surface.Most of the chemical modification reactions have been conducted in liquid phase'-8 except for a few c~s~s ,~~' ' although problems as residual solvent on surface and swelling of the substrate are experienced in the XPS measurement. Gas phase reactions have been tried here to avoid such problems. I n the h t part of the paper, we report a preliminary study of gas phase chemical modification reactions, in which the detection limit and quantitativity are examined for primary amine, carboxylic, and hydroxyl groups on polymer surface.

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The oxygen ion-beam-induced ripples observed during depth profiling of the GaAs surface by secondary-ion mass spectrometry has been studied by scanning tunneling microscopy. Under the O+2 primary-ion bombardment with energy of 10.5 kV at an incident angle of 37°, ripples of wavelength of 230 nm with the ridge lines perpendicular to the beam direction are formed, and they are grown to ∼80 nm in amplitude on the sputtered surface. Secondary-ion intensity changes abruptly in accordance with the development of ripples when they reach an amplitude of 30–50 nm. The phenomenon occurs only when the primary beam direction is perpendicular to the ridge orientation. It suggests that the ion yield enhancement is effected by increase of local concentration of oxygen implanted onto the rippled surface. Dependence of the enhancement on sputtered elements also seems to agree with the proposed mechanism.

Roughening procedures including the early stage of the O,+-induced ripple formation of GaAs were studied quantitatively by scanning tunnelling microscopy (STM). Detailed examinations of the beginning of topography develop ment using fast Fourier transform of the STM images revealed that the ripple formation was not caused by any accidental defects, particles or original irregularity on the substrate, but solely by the conditions of the ion b e a m A systematic investigation of the rippled GaAs surface produced under various 0,' bombardment conditioas was conducted. The ripple wavelength and the transition depth were almost exactly proportional to E,.cos 0, where Ep and 8 are the energy of the ion beam and the incident angle, respectively. For GaAs, the secondary ion yield transition occurs when the slope of ripples facing the incident'0,' beam reaches a saturation angle of 20-30" from the macroscopic surface plane. Topography change on other 111-V semiconductors was also examined for comparison. There was no ripple generation observed for Gap; InP gave a ripple-like structure without secondary ion yield change. A relatively rough surface resulted on GaSb and InAs at a much shallower depth than for GaAs. Rippling and ion yield changes during depth profiling have been suppressed successfully by sample rotation even in a magnetic sector-based instrument.

Atomic force microscopy (AFM) was applied to the precise thickness measurements of thin lamellae about 10 nm thick of polyethylene single crystals which were grown from dilute solutions and precipitated on cleaved mica. The obtained values agree well with the thickness determined by small angle X-ray scattering. Moreover, AFM observation allowed determination of the thickness difference of several angstroms in the different growth sectors of small crystals about several µ m wide. From the measurements, it was concluded that the free energy of the fold surface in the 110 growth sector was 30% larger than the values in the 100 sector. The larger surface free energy in the 110 sector means higher fold energy in the growth sector.