TY - JOUR

T1 - H/D-isotope effects in chemical wave propagation on surfaces

T2 - The O2+H2 and NO+H2 reactions on Rh(110) and Rh(111)

AU - Schaak, A.

AU - Shaikhutdinov, S.

AU - Imbihl, R.

PY - 1999/2/4

Y1 - 1999/2/4

N2 - H/D-isotope effects in chemical wave propagation in the bistable O2+H2 reaction on Rh(110) and Rh(111) and in the excitable NO+H2 reaction on Rh(110) were investigated using photoemission electron microscopy (PEEM) as spatially resolving method. The systems were studied in the 10-6-10-4 mbar range between 400K and 700K. For equivalent partial pressures, i.e., partial pressures which have been corrected for the different impingement rates of H2 and D2, front and pulse propagation with H2 is typically faster than with D2 up to a factor of three. A similar difference exists with respect to the width of the existence range for pattern formation in pH2(D2), which is broader with D2 than with H2. Titration experiments of the oxygen-covered Rh(110) surface demonstrated that at high oxygen coverages, the reactive sticking of D2 is inhibited much more strongly than with H2. From the T-dependence of the front velocities, apparent activation energies were determined for the two isotopes.

AB - H/D-isotope effects in chemical wave propagation in the bistable O2+H2 reaction on Rh(110) and Rh(111) and in the excitable NO+H2 reaction on Rh(110) were investigated using photoemission electron microscopy (PEEM) as spatially resolving method. The systems were studied in the 10-6-10-4 mbar range between 400K and 700K. For equivalent partial pressures, i.e., partial pressures which have been corrected for the different impingement rates of H2 and D2, front and pulse propagation with H2 is typically faster than with D2 up to a factor of three. A similar difference exists with respect to the width of the existence range for pattern formation in pH2(D2), which is broader with D2 than with H2. Titration experiments of the oxygen-covered Rh(110) surface demonstrated that at high oxygen coverages, the reactive sticking of D2 is inhibited much more strongly than with H2. From the T-dependence of the front velocities, apparent activation energies were determined for the two isotopes.

KW - Catalysis

KW - Hydrogen

KW - Nitrogen oxides

KW - Oxygen

KW - Pattern formation

KW - Photoemission electron microscopy (PEEM)

KW - Rhodium

KW - Single crystal surfaces

KW - Surface chemical reaction

KW - Surface diffusion

UR - http://www.scopus.com/inward/record.url?scp=0033521828&partnerID=8YFLogxK

U2 - 10.1016/S0039-6028(98)00855-3

DO - 10.1016/S0039-6028(98)00855-3

M3 - Article

AN - SCOPUS:0033521828

VL - 421

SP - 191

EP - 203

JO - Surface science

JF - Surface science

SN - 0039-6028

IS - 1-2

ER -