Molecular dissociation diffraction

Studies of Molecular Dissociation by Means of Ultrafast Absorption and Emission Spectroscopy and Picosecond X-Ray Diffraction P, M. Rentzepis and B. Van Wonterghem... 

Fujihisa H, Fuju Y, Takemura K, Shimomura O (1995) Stmctural aspects of dense soUd halogens under high pressure studied by x-ray diffraction - molecular dissociation and metallization. J Phys Chem SoUds 56 1439-1444... 

Carbon deposition from CO on a cobalt catalyst at low pressures is known to be a structure-sensitive process. CO is adsorbed molecularly on the low index surfaces (Co (0001)), but its dissociation occurs on the Co (1012), Co (1120), and polycrystalline surfaces.5762 Deposition of carbon on Co (1012) and the probable formation of Co3C have been established by Auger emission spectroscopy (AES) and low-energy electron diffraction (LEED) techniques.66... 

The translational and internal energy dependences of the dissociation probability can yield a great deal of information regarding the PES, but the final state is not fully specified (only given as dissociated or not dissociated) and this leads to some loss of information. Much more detail can be obtained by examining the scattered fraction instead. Diffraction intensities tell us about the surface site dependence of the PES, while comparison of the internal state populations before and after scattering tells us about the changes of vibrational and rotational state, and hence about the curvature of elbow PESs and the molecular orientation dependence of the PES. 

The TiOiCllO) surface facilitates both molecular and dissociative adsorption of formic acid. The dissociative adsorption of formic acid (to form surface formates) is mediated by surface oxygen anions low-energy electron diffraction studies have shown that formate is ordered into (2x1) domains with formates bridging the surface titanium cations. This ordered layer is disrupted on heating formate may recombine with surface hydroxyl groups to desorb formic acid (reverse of reaction 2) or it may decompose to form the dehydration products CO and H2O, as well as small amounts of CO2 and H2 [43]. 

Although infrared absorption intensities are very sensitive to molecular orientation, deriving quantitative information about molecular orientation is not easy [33,34], On the other hand, photoelectron diffraction is relatively easily interpreted to yield adsorbate orientations on surfaces. X-ray photoelectron diffraction and density functional theory calculations have been used in tandem to study the orientations of D- and L-cysteine adsorbed on the Au(17, 11, 9) surface (Fig. 4.9) [35]. Cysteine is an amino acid with the functional group R = CH SH. On the gold surface the S-H bond dissociates to give a thiolate bond to the surface. X-ray photoelectron diffraction of the N Is level indicates that the N-C bond in o-cysteine is oriented roughly parallel to the step edge on the Au(17, 11, 9) surface while the N-C bond in... 

The adduct TiMe4(THF)2 has been isolated. This compound dissociates partially in //-pentane to form TiMe4(THF). The molecular structure of the latter has been determined by X-ray diffraction and shows the titanium atom in a trigonal-bipyramidal geometry, with the THF molecule in axial position.204 The adduct TiMe4(Me2PCH2CH2PMe2) has been synthesized by addition of diphosphine to a solution TiMe4 in diethyl ether its X-ray crystal structure has been determined.205... 

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