Molecular structure of benzene coadsorbed with carbon monoxide on palladium(111): a dynamical low-energy electron diffraction analysis

A diffuse LEED study of the adsorption structure of disordered benzene on Pt(111)

“…We may also compare the present benzene structure with our earlier structures on Rh(111) and Pd(111), which were ordered due to CO coadsorption [6][7][8]. On both those surfaces, the benzene molecules were found centered on hollow sites (fcc hollow on Pd, hcp hollow on Rh).…”

“…An ARUPS investigation concluded on the other hand that a C3 11 ( u d) Kekule distortion exists in this system [8]. Fo.r comparison, the C-C single, double and triple bond lengths are 1.54, 1.33 and 1.20A, resp.…”

“…For instance, coadsorbing CO and benzene on Rh(111) changes the adsorption site of benzene from bridge to hollow [6,7]. And conversely, benzene changes the adsorption site of CO towards higher coordination on Rh(111), although apparently not on Pt(lll) (the CO site assignment when coadsorbed with benzene on Pt(lll) is uncertain though [3]) and not on Pd{111) [8]. Also the C-0 bond elongates upon coadsorption with hydrocarbons (3,6-8].…”

“…Pure benzene does not order on Pt(111) at the temperatures considered. Therefore, coadsorption with CO has proved invaluable since it induces ordering on this, and other transition metal, surfaces [3,[6][7][8]. H~wever, it is not known to what extent CO influences the structure of the benzene ring observed in these studies.…”

Video-STM, LEED and X-ray diffraction investigations of PTCDA on graphite

“…In addition, structural aspects of adsorbatesubstrate interactions have been reported in a number of low energy electron diffraction (LEED) and scanning tunneling microscopy (STM) studies of other aromatic molecules, such as benzene [3,4] and naphthalene [5][6][7], perylene and coronene [8], and of several phthalocyanines [9,10] on various metal surfaces with different reactivities and symmetries. Examples showing the dependence of molecular order on the size of the molecules are LEED-investigations of n-paraffines of different length on a Pt(lll)-surface [11,12] and of coronene and hexa-peri-benzocoronene on graphite(0001) and MoS2(0001 ) [13].…”