Temperature programmed desorption (TPD) and X-Ray photoelectron spectroscopy (XPS) studies on clean polycrystalline graphite under Ultra High Vacuum conditions are described. The same three strongly bound oxygenated species are formed after O 2 , CO 2 and H 2 0 adsorption. They decompose to give CO at 973, 1093 and 1253 K. Small amounts of CO 2 are also produced after adsorption of these gases, with desorption temperatures at 463, 573, 693, 793 and 793 K. Attempts are made to ascribe these TPD features more precisely. After H 2 0 adsorption, some H2 is evolved at ca. 1300 K. Hydrocarbons (C l -C 6 ) are also produced, but is smaller amounts. A general mechanism is proposed for the gasification reactions of graphite with O 2 , CO 2 and H 2 0. Physical wetting of the clean graphite surface leads to a H 2 0 molecule re\'ersibly bound to the carbon surface. According to XPS data, a hydrate type of bond is proposed. Considerations on the non-catalytic as well as on the catalytic steam gasification of graphite are made. It is suggested that in both cases the reaction is not only controlled by the desorption of the products, i. e. the decomposition of the surface intermediates, but also by the sticking probability of the H 2 0 on the graphite edges.

films prepared by DC-magnetron sputtering in an :Ar mixture exhibit strong p~o t~l~r n i~e s c e~c~ (P peaks superimposed upon the Raman § c a t t e~~~g spectrum. PL becomes observable at a ent of ca. 34%, and increases expmentially en by the progressive saturation of carbon d~g~i n g bonds. In this %R range, hardness and elastic ~o d u l u s decrease and CSS durability reaches an optimu~. The Raman G peak position i s very sensitive to de~os~tion ~em~erature (shift of 0.1 crn-l/'C) and was found to correlat~ with the sp3/sp2 bonding ratio as measured by EELS, and therefore can also be used as a ~r e~i c t Q r of carbon tribological performance.

Temperature programmed desorption (TPD) results after chemisorption of carbon monoxide (CO) and carbon dioxide (C0 2 ) on polycrystalline graphite are presented. CO adsorbs onto graphite 'with a very low sticking coefficient « 10-12 ).After CO chemisorption, CO (mass 28 amu) desorbs in two temperature regions, between 400 and 700 K, and between 1000 and 1300 K, and CO 2 (mass 44 amu) des orbs below 950 K. The intensity of the CO 2 signal is less than one order of magnitude lower than the CO intensity. After CO 2 adsorption the major desorption product is CO at high temperatures (lOOO

This paper reviews the state of the head-disk interface (HDI) technology, and more particularly the head-medium spacing (HMS), for today's and future hard-disk drives. Current storage areal density on a disk surface is fast approaching the one terabit per square inch mark, although the compound annual growth rate has reduced considerably from ∼100%/annum in the late 1990s to 20-30% today. This rate is now lower than the historical, Moore's law equivalent of ∼40%/annum. A necessary enabler to a high areal density is the HMS, or the distance from the bottom of the read sensor on the flying head to the top of the magnetic medium on the rotating disk. This paper describes the various components of the HMS and various scenarios and challenges on how to achieve a goal of 4.0-4.5 nm for the 4 Tbit/in 2 density point. Special considerations will also be given to the implication of disruptive technologies such as sealing the drive in an inert atmosphere and novel recording schemes such as bit patterned media and heat assisted magnetic recording.

The surface chemistry of fluorinated ethers and fluorinated alcohols adsorbed on amorphous nitrogenated carbon (a-CN x ) have been studied as models for the interaction of perfluoropolyalkyl ether (PFPE) lubricants with the surfaces of magnetic data storage media. Temperature-programmed desorption experiments conducted in ultrahigh vacuum using small fluorinated ethers and fluorinated alcohols have measured their desorption energies and have provided insight into the nature of bonding between PFPEs and a-CN x films. Preliminary results indicate that ether linkages interact with a-CN x films through electron donation from the oxygen lone pair electrons. In contrast, alcohol end groups show evidence of hydrogen bonding with a-CN x films. The models derived from this study can aid in the future development of both lubricants and protective overcoats to ensure that the magnetic hard disks display optimal wear resistance and performance.