angle-resolved photoemission - theory and current appln. [surface sci.., catal. 74] - s. kevan (elsevier, 1992) ww

[...]... component of the final state wave-fiinction is damped by many-body effects, giving a finite mean free path (section 3.2), and this has the effect of smearing out direct transitions (section 3.4) and enhancing surface sensitivity - 18 I I I I I I “ “ I -2 0 -1 8 -1 6 -1 4 -1 2 -1 0 - 8 -6 -4 - 2 0 INITIAL STATE ENERGY (eV) Figure 1: Normal emission photoemission from Mg(0001), AI(001) and Be(0001) [9] Direct bulk... the diagrammatic and pcrt.urha.tion approach to many-body theory is based The Green function is given by: G(r,r';E) = s (N,O14+(rf)P I , ~ ) ( - 1,sI4(r)W,O) N E - Eo t E, -is sumsover the excitations of the ( N - 1)-electron system (hole states) and the (N+l)-electron system (electron states) [16] It is time-ordered, meaning that the denominator for the hole states contains -is, and for the electron... of 50 - 100 eV These effects must be included in an accurate description of photoemission I n this chapter we shall concentrate an the way that one-electron energy bands show up in photoemission, in spite of the complicated electron-electron interactions in solids These bands really describe the excitations of quasiparticles - screened electrons or holes - and much of the current interest in photoemission. .. Eugene, OR USA 97403 16) Future Prospects in Angle-ResolvedPhotoemission S.D Kevan, Physics Department, University of Oregon, Eugene, OR USA 97403 1 Chapter 1 INTRODUCTION N.V SMITH AND S.D =VAN From humble beginnings in the early 1970's, angle-resolved photoemission spectroscopy (ARPES) has become established as an indispensable tool for the investigation of solids and their surfaces This book represents... Ol~+(r)lN,O), (time-reversed) plane-wave state k incident on the N-electron system in the ground state; in (k; N - l,sJ$+(r)lN - l , j ) , the electron is incident on the ( N - 1)-electron system in an excited state s, and changes the state from s to j 22 Fortunately, the matrix element (k; N - l , s J G + ( r ) J N l , s ) , in which the photoelectron does not change the state of the ( N - 1)-electron system,... [17]: + x (k; N - 1 , s 1 &+(r”)1 N - 1,s) = ( E k , s - E , ) ( k ; N - 1,s I &+(r)I N - 1,s) Here, G is the Green function for the one-electron part of the Hamiltonian, and: fi,s(r) = /dr’(N - 1 , s /4+(r‘)d(r’)1 N - l,l)v(r’,r) (24) (23) is an effective single particle equation for the photoelectron quasiparticle amplitude, containing the self-energy: This is essentially the same self-energy that appears... behind, 1 k; N - 1, s ) This final state can be found by preparing the [ N - 1)-electron system in state s , shooting a free-electron wave with wave-vector -k at the system and letting them interact - finally taking the complex conjugate of the resulting N-electron wave-function 2.2 Transitions to the final state As we shall see throughout this book, a great deal can be learnt from photoemission spectra... point-to-point focussing and the fact that the output focal surface is plane, which lends itself well to parallel detection using microchannel plates The SDA is inherently angle-selective, and a crude angle-resolved experiment can be done simply by tilting a sample in front of a fixed SDA It is now common practice, however, to mount a modest-sized (typically 50 mm radius) SDA on a one-axis or two-axis... Photoemission and the Electronic Properties of Surfaces, B Feuerbacher, B Fitton and R F Willis, eds (Wiley, New York, 1978) 37 M.S Hybertson and S.G Louie, Phys Rev Lett 55, 1418 (1985); M.S Hybertson and S.G Louie, Phys Rev B34, 5390 (1986); J.E Northrup, M.S Hybertson, and S.G Louie, Phys Rev Lett 59,819 (1987) 38 H.J Levinson, E.W Plummer, and P.J Feibelmann, Phys Rev Lett 43,952 (1979) 39 S D Kevan, ... sensitivity in photoemission To understand the quasiparticle properties of the final state more fully, let us go back to the many-body Golden Rule (section 2.1) [17] Writing the matrix element between the many-body states as: + (k; N - 1,s 16H I N,O) = /dr(k; N - 1,s I G+(r)$(r) [ N,O)SH(r), we can insert a complete set of states of the ( N - 1)-electron system: (k;N- 1,s 16H 1 N,O) = x / d r ( k ; N - 1,s . 1,4 000 Dusseldorf 1, FRG, and C. Carbone, Institut fur Festkorperforschung der Kernforschungsanlage Julich GmbH, Postfach 191 3, D-5170 Julich, FRG. Spin- and Angle-Resolved Photoemission. beginnings in the early 1970&apos ;s, angle-resolved photoemission spectroscopy (ARPES) has become established as an indispensable tool for the investigation of solids and their surfaces. This. class="bi x0 y0 w0 h0" alt="" Studies in Surface Science and Catalysis 74 ANGLE-RESOLVED PHOTOEMISSION Theory and Current Applications This Page Intentionally Left Blank Studies in Surface