Wavelength dependence of the photochemistry of O2 on Pd(111) and the role of hot electron cascades

The photochemistry of O2 adsorbed on Pd(111) has been studied as a function of the energy of the exciting photons in the range of hν=3.9–6.4 eV. The obtained data are reproduced by a proposed kinetic model considering photostimulated desorption and dissociation, whereby the latter gives rise to additional displacement processes. This modeling yields rate constants and, hence, cross sections for the respective processes. It is found that the cross sections for all processes rise exponentially with photon energy. This result motivates a study of the distribution of hot electrons generated by laser irradiation, and its decay via electron‐hole pair scattering events resulting in a broad secondary electron distribution. The energetic and spatial distribution of these electrons is calculated. The probability for these electrons to tunnel into an adsorbate affinity level is modeled and compared to the observed photo cross sections.

[1]  G. Ertl,et al.  Polarization probe of excitation mechanisms in surface photochemistry , 1991 .

[2]  Jeffrey Bokor,et al.  Direct measurement of nonequilibrium electron-energy distributions in subpicosecond laser-heated gold films , 1992 .

[3]  Fujimoto,et al.  Femtosecond studies of nonequilibrium electronic processes in metals. , 1987, Physical review letters.

[4]  G. Ertl,et al.  Excitation mechanism in the photodissociation of dioxygen adsorbed on Pd(111) , 1991 .

[5]  Emilio Segrè,et al.  Nuclei And Particles , 1977 .

[6]  G. Jw.  Inelastic resonance scattering, tunneling, and desorption. , 1991 .

[7]  J. W. Gadzuk,et al.  Hot-Hole—Electron Cascades in Field Emission from Metals , 1971 .

[8]  B. Hellsing.  Direct mechanism for photoinduced desorption and dissociation of O2 on Pt(111) , 1993 .

[9]  I. Harrison,et al.  Photoreaction dynamics of CO oxidation on Pt(111) , 1992 .

[10]  J. White,et al.  Photoinduced pathways to dissociation and desorption of dioxygen on silver (110) and platinum (111) , 1991 .

[11]  W. Ho,et al.  Photochemistry of oriented molecules coadsorbed on solid surfaces: The formation of CO2+O from photodissociation of O2 coadsorbed with CO on Pt(111) , 1989 .

[12]  R. Imbihl,et al.  Adsorption of oxygen on a Pd(111) surface studied by high resolution electron energy loss spectroscopy (EELS) , 1986 .

[13]  P. Antoniewicz.  Model for electron- and photon-stimulated desorption , 1980 .

[14]  R. H. Ritchie.  Coupled Electron‐Hole Cascade in a Free Electron Gas , 1966 .

[15]  G. Ertl,et al.  Photodissociation and photodesorption of O2 adsorbed on Pd(111) , 1992 .

[16]  R. Cavanagh,et al.  State‐resolved evidence for hot carrier driven surface reactions: Laser‐induced desorption of NO from Pt(111) , 1989 .

[17]  A. Lagendijk,et al.  Ultrafast relaxation of electrons probed by surface plasmons at a thin silver film. , 1990, Physical review letters.

[18]  C. N. Berglund,et al.  Photoemission Studies of Copper and Silver: Theory , 1964 .

[19]  J. White,et al.  Surface photochemistry. II. Wavelength dependences of photoinduced dissociation, desorption, and rearrangement of O2 on Pt(111) , 1989 .

[20]  R. Cavanagh,et al.  Constraints on the use of polarization and angle-of-incidence to characterize surface photoreactions , 1991 .

[21]  Xiao Zhu,et al.  Surface photochemistry 15: On the role of substrate excitation , 1990 .

[22]  G. Ertl,et al.  The adsorbate state specific photochemistry of dioxygen on Pd(111) , 1990 .

[23]  Hirayama,et al.  Adsorbate structure and angular dependence of desorption dynamics: O2 photodesorbed from Pd(111). , 1993, Physical Review Letters.

[24]  W. Ho,et al.  THEORETICAL ASPECTS OF PHOTOINITIATED CHEMISORPTION, DISSOCIATION, AND DESORPTION OF O2 ON PT(111) , 1992 .

[25]  Lagendijk,et al.  Effect of a nonthermal electron distribution on the electron-phonon energy relaxation process in noble metals. , 1992, Physical review. B, Condensed matter.

[26]  J. Yates,et al.  Photon-induced processes for chemisorbed O2 on Pd(111): effect of light polarization , 1990 .

[27]  P. Siegbahn,et al.  A THEORETICAL-STUDY OF THE PEROXO AND SUPEROXO FORMS OF MOLECULAR-OXYGEN ON METAL-SURFACES , 1988 .

[28]  Baba,et al.  Bonding, structure, and magnetism of physisorbed and chemisorbed O2 on Pt(111). , 1990, Physical review letters.

[29]  J. Yates,et al.  Photolysis of a simple molecule on a metal surface—adsorbed O2 dissociation and desorption on Pd(111) , 1989 .

[30]  W. A. Dench,et al.  Quantitative electron spectroscopy of surfaces: A standard data base for electron inelastic mean free paths in solids , 1979 .

[31]  B. Koel,et al.  Interaction of oxygen with Pd(111): High effective O2 pressure conditions by using nitrogen dioxide , 1990 .

[32]  P. Siegbahn,et al.  The mechanism for the O2 dissociation on Ni(100) , 1989 .

[33]  J. Yates,et al.  Adsorption kinetics and isotopic equilibration of oxygen adsorbed on the Pd(111) surface , 1989 .

[34]  N. Christensen.  Electronic structure of palladium and its relation to uv spectroscopy , 1976 .

[35]  T. Engel.  A molecular beam investigation of He, CO, and O2 scattering from Pd(111) , 1978 .

[36]  William E. Spicer,et al.  Monte Carlo Calculations Pertaining to the Transport of Hot Electrons in Metals , 1964 .

[37]  E. O. Schulz-Dubois,et al.  Laser Handbook , 1972 .

[38]  G. Somorjai,et al.  The angular and velocity distributions of NO scattered from the Pt(111) crystal surface , 1982 .

[39]  J. Yates,et al.  Photolysis of chemisorbed dioxygen on Pd(111): Dependence on photon energy , 1989 .

[40]  P. Stair,et al.  Calculations of the surface temperature rise and desorption temperature in laser‐induced thermal desorption , 1986 .