Surface Vibrational and Electron Spectroscopy - Experiments and first-principle calculations
(2004)- Abstract
- This work deals with interpretation of experimental surface spectroscopic data with the aid of first-principle calculations. Surface infrared reflection-absorption spectra as well as spectra from the electron spectroscopic methods photoemission and X-ray absorption are considered. In all cases the surface is modeled by a metal cluster with the same (frozen) geometry as part of the surface.
The work on surface vibrational spectra has aimed at including anharmonic effects using first-principles calculations. Anharmonicity influences surface adsorbate vibrations in two ways. First, the frequencies are lowered as compared to the harmonic frequencies. Second, anharmonic resonances mix C-H stretch fundamentals and binary C-H... (More) - This work deals with interpretation of experimental surface spectroscopic data with the aid of first-principle calculations. Surface infrared reflection-absorption spectra as well as spectra from the electron spectroscopic methods photoemission and X-ray absorption are considered. In all cases the surface is modeled by a metal cluster with the same (frozen) geometry as part of the surface.
The work on surface vibrational spectra has aimed at including anharmonic effects using first-principles calculations. Anharmonicity influences surface adsorbate vibrations in two ways. First, the frequencies are lowered as compared to the harmonic frequencies. Second, anharmonic resonances mix C-H stretch fundamentals and binary C-H deformation overtones and combinations and therefore redistribute the harmonic intensity only found in the C-H stretch fundamental. We show that by using a sophisticated model for anharmonicity based on density-functional electronic structure calculations and 2nd order perturbation theory both these effects can be included without scaling the harmonic frequencies. In order to save computational time anharmonic effects are calculated for a corresponding free molecule and excellent agreement between experiments and calculations is demonstrated for a few adsorbates adsorbed on Cu(100). Frequencies, relative intensities and the number of observed modes are all reproduced.
Photoemission and x-ray absorption data have been modeled using electronic structure calculations for the density-functional method B3LYP on metal clusters including only a single metal atom. For the system studied this simple model reproduces virtually all experimental results, such as binding energy shifts, valence photoemission spectra and x-ray absorption spectra and thus allows for easy and detailed spectral interpretation. (Less) - Abstract (Swedish)
- Popular Abstract in Swedish
75% av alla kemiska reaktioner sker på en yta av något slag. En av anledningarna till detta är att många ytor har en katalytisk effekt. Inom kemins värld är en katalysator något som påskyndar en kemisk reaktion utan att själv förbrukas, och ett tydligt exempel på en katalytiskt aktiv yta är en bilkatalysator, vilken i princip består av en varm metallyta. På denna yta omvandlas gaser från motorförbränningen som är giftiga och förstör ozonlagret till ofarliga gaser som sen släpps ut från avgasröret. Vår forskning syftar till att öka förståelsen för den grundläggande växelverkan mellan små organiska molekyler och metallytor. Egenskaper såsom hur en molekyl sitter på metallytan, hur starkt den... (More) - Popular Abstract in Swedish
75% av alla kemiska reaktioner sker på en yta av något slag. En av anledningarna till detta är att många ytor har en katalytisk effekt. Inom kemins värld är en katalysator något som påskyndar en kemisk reaktion utan att själv förbrukas, och ett tydligt exempel på en katalytiskt aktiv yta är en bilkatalysator, vilken i princip består av en varm metallyta. På denna yta omvandlas gaser från motorförbränningen som är giftiga och förstör ozonlagret till ofarliga gaser som sen släpps ut från avgasröret. Vår forskning syftar till att öka förståelsen för den grundläggande växelverkan mellan små organiska molekyler och metallytor. Egenskaper såsom hur en molekyl sitter på metallytan, hur starkt den binder, hur den lutar, e.t.c. styr i sin tur vilka kemiska reaktioner som kan ske på ytan. Genom att kombinera experiment och modellberäkningar kan vi undersöka och dra slutsater om dessa egenskaper och därmed öka förståelsen för bl.a. heterogen katalys. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/466599
- author
- Andersson, Martin LU
- supervisor
- opponent
-
- Tobin, Roger G., Dep. of Physics and Astronomy, Tufts University, USA
- organization
- publishing date
- 2004
- type
- Thesis
- publication status
- published
- subject
- keywords
- gränsskikt, anharmonicity, Ytkemi, Surface and boundary layery chemistry, adsorbates, metal surface, density functional theory, first-principle calculations, electron spectroscopy, reflection-absorption infrared spectroscopy, vibrational spectroscpy
- pages
- 224 pages
- publisher
- Martin Andersson, Östervång 30, 247 32 Södra Sandby, Sweden,
- defense location
- Lund University, Chemical Center, Lecture hall A
- defense date
- 2004-01-30 13:00:00
- ISBN
- 91-7422-041-1
- language
- English
- LU publication?
- yes
- additional info
- Article: M.P.Andersson, P.Uvdal, J.Phys.Chem.B (2001), 105, 9548-9462 Article: M.P.Andersson, P.Uvdal, Surface Science, in press Article: M.P.Andersson, P.Uvdal, A.D.MacKerell Jr., J.Phys.Chem.B (2002), 106, 5200-5211 Article: M.P.Andersson, P.Uvdal, Langmuir (2002), 18(10), 3759-3762 Article: M.P.Andersson, R.Ásmundsson, P.Uvdal, Surface Science (2003), 532-535, 221-226 Article: M.P.Andersson, P.Uvdal, Phys.Rev.Lett. (2003), 90(7), 076103 Article: M.P.Andersson, P.Uvdal, in manuscript Article: A.Sandell, M.P.Andersson, A.J.Jaworowski, J.T.Roberts, P.Uvdal, Surface Science (2002), 521, 129-138 Article: M.P.Andersson, P.Uvdal, A.Sandell, A.J.Jaworowski, J.T. Roberts, in manuscript Article: A.Sandell, M.P.Andersson, Y.Alfredsson, M.K.-J.Johansson, J.Schnadt, H.Rensmo, H.Siegbahn, P.Uvdal, Journal of Applied Physics (2002), 92(6), 3381-3387 Article: A.Sandell, M.P.Andersson, M.K.-J.Johansson, P.G. Karlsson, Y.Alfredsson, J.Schnadt, H.Siegbahn, P.Uvdal, Surface Science (2003), 530, 63-70 The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Chemical Physics (S) (011001060)
- id
- d254e622-cd4b-41e3-ab0e-36a9bc2ea64c (old id 466599)
- date added to LUP
- 2016-04-04 10:10:23
- date last changed
- 2018-11-21 20:57:13
@phdthesis{d254e622-cd4b-41e3-ab0e-36a9bc2ea64c,
abstract = {{This work deals with interpretation of experimental surface spectroscopic data with the aid of first-principle calculations. Surface infrared reflection-absorption spectra as well as spectra from the electron spectroscopic methods photoemission and X-ray absorption are considered. In all cases the surface is modeled by a metal cluster with the same (frozen) geometry as part of the surface.<br/><br>
<br/><br>
The work on surface vibrational spectra has aimed at including anharmonic effects using first-principles calculations. Anharmonicity influences surface adsorbate vibrations in two ways. First, the frequencies are lowered as compared to the harmonic frequencies. Second, anharmonic resonances mix C-H stretch fundamentals and binary C-H deformation overtones and combinations and therefore redistribute the harmonic intensity only found in the C-H stretch fundamental. We show that by using a sophisticated model for anharmonicity based on density-functional electronic structure calculations and 2nd order perturbation theory both these effects can be included without scaling the harmonic frequencies. In order to save computational time anharmonic effects are calculated for a corresponding free molecule and excellent agreement between experiments and calculations is demonstrated for a few adsorbates adsorbed on Cu(100). Frequencies, relative intensities and the number of observed modes are all reproduced.<br/><br>
<br/><br>
Photoemission and x-ray absorption data have been modeled using electronic structure calculations for the density-functional method B3LYP on metal clusters including only a single metal atom. For the system studied this simple model reproduces virtually all experimental results, such as binding energy shifts, valence photoemission spectra and x-ray absorption spectra and thus allows for easy and detailed spectral interpretation.}},
author = {{Andersson, Martin}},
isbn = {{91-7422-041-1}},
keywords = {{gränsskikt; anharmonicity; Ytkemi; Surface and boundary layery chemistry; adsorbates; metal surface; density functional theory; first-principle calculations; electron spectroscopy; reflection-absorption infrared spectroscopy; vibrational spectroscpy}},
language = {{eng}},
publisher = {{Martin Andersson, Östervång 30, 247 32 Södra Sandby, Sweden,}},
school = {{Lund University}},
title = {{Surface Vibrational and Electron Spectroscopy - Experiments and first-principle calculations}},
year = {{2004}},
}