Professor Petra Swiderek (University of Bremen): 2011-Present
Professor Leon Sanche (University of Sherbrooke, Canada): 2008-Present
M. Rajappan, L. Zhu,* A.D. Bass, L. Sanche, C.R. Arumainayagam, “Chemical Synthesis Induced by Dissociative Electron Attachment,” J. Phys. Chem. 112 (2008) 17319‒17323.
Andrew D. Bass, Christopher R. Arumainayagamand Leon Sanche, "Revisiting the electron stimulated desorption of anions from thin films of CF2Cl2," International Journal of Mass Spectrometry 277 (2008) pp. 251‒255.
Professor John Yates (University of Pittsburgh): 1994-95
Fourier transform IR reflection absorption spectroscopy (FT-IRAS) was used to probe the non-dissociative adsorption of N2 on an atomically clean Pt(111) single crystal. In contradiction to a previous IRAS study of nitrogen adsorption on a Pt(111) foil at 120 K, no nitrogen IR (IR) band was obsd. on a fully annealed Pt(111) surface at 90 K. Following Ar+ ion bombardment, adsorption of nitrogen at 90 K produces an intense IR band at .apprx. 2222cm-1 attributed to the N-N stretching mode of mol. nitrogen adsorbed on defect sites produced by ion bombardment. Annealing the Ar+ ion sputtered surface to a temp. above .apprx.750 K completely suppresses the adsorption of nitrogen at 90 K. Based on these and other results, it is postulated that nitrogen adsorbs at 90 K mainly on monovacancies on platinum. It is suggested that this specific adsorption occurs by sigma donation from nitrogen to the base of monovacancy sites which possess a low d-electron d. compared to surface Pt atoms.
The photoactivation of chemisorbed O2 in the presence of chemisorbed CO on Pt(111) has been investigated for uv light in the range 3.87–4.77 eV (260–320 nm). Three photoprocesses first-order in O2 coverage have been separated and for the first time the cross sections for each are reported. The dominant process is O2 photodissociation (Qdiss=4.0±0.1×10–21 cm2). The second most probable process is photodesorption (Qdes=2.2±0.1×10–21 cm2). The least probable process is photoreaction with chemisorbed CO (Qrxn=0.35±0.03×10–21 cm2). Previous studies of Qrxn have reported cross sections as high as 5×10–17 cm2.
Professor Cynthia Friend (Harvard University): 1990 - 1998
The reactions of ethylene glycol on Mo(110) were studied using temp.-programmed reaction, IR reflection absorption, and X-ray photoelectron spectroscopies. The major reaction pathway is double C-O bond scission to evolve gas-phase ethylene at 350 and 390 K. Both X-ray photoelectron and IR spectra demonstrate the existence of two surface intermediates, a bidentate (-OCH2CH2O-) and a monodentate (-OCH2CH2OH) species, at satn. coverage of ethylene glycol. We demonstrate that all ethylene glycol in the mixed overlayer of mono- and bidentate species reacts via a bidentate surface intermediate. Furthermore, in contrast to previous studies on other surfaces, the dialkoxide ethylene glycol intermediate is shown to be more reactive than similar monoalkoxides on Mo(110). Finally, anal. of the IR spectra demonstrates that the bidentate species adsorbs with C2 (or lower) symmetry at 300 K.
Formaldehyde (CH2O) reaction on Mo(110) is studied with temp. programmed reaction and IR reflectance absorbance spectroscopy. We present preliminary results which demonstrate the evolution of gas-phase ethylene from the formaldehyde reaction, to the best of our knowledge the first example of carbon-carbon bond formation on clean Mo(110). This reaction is proposed to proceed via an ethylene dialkoxide intermediate, analogous to that formed during reaction of ethylene glycol on Mo(110). Other reactions include hydrogenation of CH2O to form a methoxy intermediate which subsequently undergoes C-O bond scission to evolve gas-phase Me radicals at .apprx.600 K.
*Wellesley College Undergraduate