Showing papers on "Photoemission spectroscopy published in 1991"
TL;DR: In this article, the MgKα X-ray and He(I)/He(II) ultraviolet (UPS) photoelectron spectra of several thin films of C 60 (one to three monolayers) prepared by vapor deposition on gold are reported.
305 citations
TL;DR: In this paper, anion photoelectron spectroscopy has been employed to obtain vibrationally resolved spectra of the carbon molecules C2-C11 and C−C11.
Abstract: Anion photoelectron spectroscopy has been employed to obtain vibrationally resolved spectra of the carbon molecules C2–C11. The spectra of C−2–C−9 are dominated by linear anion to linear neutral photodetachment transitions. Linear to linear transitions contribute to the C−11 spectrum, as well. From these spectra, vibrational frequencies and electron affinities are determined for the linear isomers of C2–C9 and C11. The term value is also obtained for the first excited electronic state of linear C4. The spectra of C−10 and C−11 show evidence for transitions involving cyclic anions and/or neutrals. Similar types of transitions are identified in the spectra of other smaller molecules, specifically C−6, C−8, and to a lesser extent C−5.
280 citations
TL;DR: In this paper, the lifetime of the lowest triplet state of the two most stable fullerenes, C 60 and C 70, was measured in a supersonic beam by two-color resonant two-photon ionization.
166 citations
TL;DR: In this paper, the photoelectron spectrum of the NO−3 anion has been obtained at 266 and at 213 nm, and the analysis of this band indicates that the NO3 ground state has a D3h equilibrium geometry and is vibronically coupled to the 2E' second excited state via the ν4 mode.
Abstract: The photoelectron spectrum of the NO−3 anion has been obtained at 266 and at 213 nm. The 266 nm spectrum probes the 2A’2 ground state of NO3. The 213 nm spectrum represents the first observation of the 2E‘ lowest‐lying excited state of NO3. The 2A2 band shows vibrational progressions in the ν1 symmetric stretch and the ν4 degenerate in‐plane bend of NO3. Our analysis of this band indicates that the NO3 ground state has a D3h equilibrium geometry and is vibronically coupled to the 2E’ second excited state via the ν4 mode. We also obtain the electron affinity of NO3, 3.937±0.014 eV, and the heat of formation of NO3 at 298 K, 0.777±0.027 eV (17.9±0.6 kcal/mol). The 2E‘ state of NO3 lies 0.868±0.014 eV above the ground state. The 2E‘ band shows complex and extensive vibrational structure. Several possible assignments of this structure are discussed.
162 citations
TL;DR: In this article, the photoelectron spectra of clusters of I− solvated in water up to fifteen water molecules were measured and it was shown that the vertical binding energy of the electron increases with cluster size and levels off in clusters containing more than six water molecules.
Abstract: We have measured the photoelectron spectra of clusters of I‐ solvated in water up to fifteen water molecules. The vertical binding energy of the electron increases with cluster size and levels off in clusters containing more than six water molecules. These results strongly indicate that the first solvation layer around the ion consists of six water molecules. This picture is quantitatively consistent with the photoelectron spectroscopy result of I‐ solvated in bulk water.
151 citations
130 citations
TL;DR: The chemistry of the (NH4)2Sx−treated n−GaAs (100) surfaces has been studied using synchrotron radiation photoemission spectroscopy as discussed by the authors.
Abstract: The chemistry of the (NH4)2Sx‐treated n‐GaAs (100) surfaces has been studied using synchrotron radiation photoemission spectroscopy Ga 3d, As 3d, and S 2p photoemission spectra are measured before and after annealing in vacuum with a photon energy of about 210 eV, where S 2p core level spectra can be sensitively detected It is found that Ga‐S, As‐S, and S‐S bonds are formed on the as‐treated GaAs surfaces, and that stable Ga‐S bonds become dominant after annealing at 360 °C for 10 min in vacuum The thickness of the surface sulfide layer is reduced from about 05 to 03 nm by annealing The surface Fermi‐ level position of the as‐treated surfaces is determined to be about 08 eV below the conduction band minimum, which is about 01 eV closer to the valence band maximum than that of the untreated surfaces A Fermi‐level shift of 03 eV toward a flat band condition is also observed after annealing It is found that the Ga‐S bonding plays an important role in passivating GaAs surfaces
117 citations
TL;DR: In this article, the low-lying electronic states of Si−2 and Si2 were studied using both photoelectron spectroscopy and threshold photodetachment (P2P) of Si −2, and it was shown that the ground state of Si2 is the X 3 Σ−g state.
Abstract: The low‐lying electronic states of Si−2 and Si2 were studied using both photoelectron spectroscopy and threshold photodetachment spectroscopy of Si−2 . Our measurements show that the ground state of Si2 is the X 3Σ−g state and that the X 3Σ−g–D 3Πu splitting is 0.083±0.010 eV. Additional spectroscopic constants for the X 3Σ−g, D 3Πu, a 1Δg, b 1Πu and c 1Σ+g states of Si2 were also determined. For Si−2 , the first two electronic states were identified as: 2Πu (Te =0, re =2.207±0.005 A, and ν=533±5 cm−1) and 2Σ+g (Te =0.025±0.010 eV, re =2.116±0.005 A, and ν=528±10 cm−1). The electron affinity for Si2 was found to be 2.176±0.002 eV. Our results provide definitive orderings and splittings for the low‐lying electronic states in both Si2 and Si−2 .
114 citations
TL;DR: In this paper, a separable Green's function matrix method was applied to a multiple scattering treatment of photoelectron diffraction and Auger electron diffraction, which can be used to simulate emission from linear and bent chains of atoms.
83 citations
TL;DR: In this paper, the mixed-valence states in Cs2AuIAuIIIX6 (X = Cl, Br or I) were systematically studied by X-ray photoelectron spectroscopy of the Au 4f region for the first time.
Abstract: The mixed-valence states in Cs2AuIAuIIIX6(X = Cl, Br or I) were systematically studied by X-ray photoelectron spectroscopy of the Au 4f region for the first time. The gold valence states in halogeno complexes of AuI and AuIII were also studied. In Cs2Au2X6 the difference between the oxidation state of AuI and that of AuIII decreases as the covalency of the –AuI–X–AuIII–X– bonds increases in the order X = Cl < Br < I, because the charge-transfer interaction between AuI and AuIII through the bridging halogen becomes stronger in this order. In the non-stoichiometric CsAu0.6Br2.6 the oxidation state of Au is considered to be almost homogeneous.
78 citations
TL;DR: In this paper, the influence of steps and point defects on the reactivity of TiO 2 (100) to H 2 O has been examined using photoemission spectroscopy.
TL;DR: In this paper, the angular distribution of a single rotational state of a photoelectron was observed to have a strong dependence on the change in ion core rotation and the angle between the linear polarization vectors of the two light beams.
Abstract: Time‐of‐flight photoelectron spectroscopy has been used to record energy‐resolved photoelectron angular distributions (PADs) following (1+1’) resonance‐enhanced multiphoton ionization (REMPI) of NO via the vi=1,Ni=22 rovibrational level of the A 2∑+ state. The PADs corresponding to single rotational states of the resulting molecular ion show a strong dependence on the change in ion core rotation ΔN(≡N+−Ni) and also on the angle between the linear polarization vectors of the two light beams. Broken reflection symmetry [I(θ,φ)≠I(−θ,φ)] is observed when the polarization vectors of the two light beams form an angle of 54.7°. A fit to the PADs provides a complete description of this molecular photoionization, namely, the magnitudes and phases of the radial dipole matrix elements that connect the intermediate state to the ‖lλ〉 photoelectron partial waves (Refs. 1 and 2). This information is then used to predict unobserved quantities, such as ion angular momentum alignment and the full three‐dimensional form of ...
TL;DR: In this paper, the binding energy of H 2 O on Ru(001) was investigated by photoemission spectroscopy (UPS and XPS), LEED and workfunction measurements in the temperature range 120-300 K. The O1s spectra of adsorbed H 2O layers always showed a contribution near 531.3 eV binding energy although the main intensity was located at 532.7 eV.
TL;DR: In this paper, the vibrational spectrum of the phenol H2O cation complex was obtained by two-colour resonant pump-probe zero kinetic energy (ZEKE) spectroscopy.
TL;DR: The ultraviolet negative ion photoelectron spectrum of Pd−2 is presented for electron binding energies up to 3.35 eV in this paper, where the anion is prepared by sputtering in a flowing afterglow ion source.
Abstract: The ultraviolet negative ion photoelectron spectrum of Pd−2 is presented for electron binding energies up to 3.35 eV. The anion is prepared by sputtering in a flowing afterglow ion source. Multiple low‐lying electronic states of Pd2, all unidentified previously, are observed with resolved vibrational structure. The spectrum shows two strong electronic bands, each with similar vibrational progressions. Franck–Condon analyses are carried out on the two transitions and molecular constants are extracted for the anion and the two neutral electronic states. With the help of simple molecular orbital arguments and ab initio calculations, these two electronic bands are assigned as the triplet ground state (3Σ+u) and a singlet excited state (1Σ+u). The adiabatic electron affinity is E.A.(Pd2)=1.685±0.008 eV and the singlet excitation energy T0(1Σ+u) is 0.497±0.008 eV (4008±65 cm−1 ). The bonding in the palladium dimers is discussed and we find that the anion bond strength is 1.123±0.013 eV stronger than that of the...
TL;DR: In this article, the SiO2/Si interface structure of thin oxide films thermally grown on Si(100), (111), and (110) surfaces under device processing conditions has been investigated using high-resolution photoemission spectroscopy with synchrotron radiation.
Abstract: The SiO2/Si interface structure of thin oxide films thermally grown on Si(100), (111), and (110) surfaces under device processing conditions has been investigated using high‐resolution photoemission spectroscopy with synchrotron radiation. The intensity distribution of the so‐called suboxides, Si1+, Si2+, Si3+, displays a strong dependence on the crystallographic orientation of the substrate over the oxidation temperature range from 600 to 900 °C; Si1+ is enhanced in intensity on Si(111) and (110), while the Si2+ intensity is larger than the Si1+ one on Si(100). This orientation dependence is explained in terms of the bond topology of the substrate surface. A Si(110) surface exhibits a rather large Si3+ intensity as compared to Si(100), (111) surfaces, suggesting that Si–Si bonds on the outermost layer of a Si(110) surface are easily broken by oxygen atoms to generate the bridge bond Si–O–Si. The presence of an interfacial Si atom to which hydrogen is bonded is clearly observed. The total suboxide intensity, i.e., the sum of the suboxide intensities depends on both oxidation temperature and substrate orientation, which is interpreted by means of the interfacial roughness and the surface Si atom density of the substrate. It is shown that an ordered crystalline phase of SiO2 is present at the interfacial region. The generation of this phase has a Si(111)‐preferred orientation.
TL;DR: In this article, a Franck-Condon analysis of the relative intensities of the observed transitions was used to obtain a 1.670 (10) A and a CuO − vibrational frequency of 739 (25) cm −1 for the Y 2 Σ + excited state of CuO.
Abstract: Laser photoelectron spectroscopy has been used to study the CuO − anion and neutral CuO molecule. Analysis of the photoelectron spectrum yields an electron affinity of 1.777 (6) eV for CuO. Equilibrium bond lengths and vibrational frequencies are obtained from a Franck-Condon analysis of the relative intensities of the observed transitions, yielding a CuO − bond length of 1.670 (10) A and a CuO − vibrational frequency of 739 (25) cm −1 . The analysis also yields a bond length (1.704 (10) A) and a vibrational frequency (682 (25) cm −1 ) for the Y 2 Σ + excited state of CuO
TL;DR: In this paper, a tunable extreme ultraviolet (XUV) radiation of narrow bandwidth (0.6 cm−1) is generated in the region of 130000 cm −1.
TL;DR: In this paper, the Buckingham-Orr-Sichel equations were used to obtain high-resolution threshold photoelectron spectra for the (000, (010), (020), and (100) vibrational states of the N2O(+) cation.
Abstract: Pulsed field ionization (PFI) has been used in conjunction with a coherent VUV source to obtain high-resolution threshold photoelectron spectra for the (000), (010), (020), and (100) vibrational states of the N2O(+) cation. Simulations for the rotational profiles of each vibronic level were obtained by fitting the Buckingham-Orr-Sichel equations using accurate spectroscopic constants for the ground states of the neutral and the ion. The relative branch intensities are interpreted in terms of the partial waves of the outgoing photoelectron to which the ionic core is coupled and in terms of the angular momentum transferred to the core.
TL;DR: In this article, the authors used threshold photodetachment spectroscopy to obtain vibrationally resolved photoelectron spectra of G&-l1 at a resolution of about 100 cm- ‘.
Abstract: have obtained vibrationally resolved photoelectron spectra of G&-l1 at a resolution of about 100 cm- ‘. This resolution is comparable to the lowest vibrational frequencies for these clusters, and not all features in the spectra were cleanly resolved. In this Communication, we report a considerably higher resolution (6-10 cm-’ ) photodetachment study of C< using threshold photodetachment spectroscopy.*v9 We observe considerably more vibrational structure than in the CT photoelectron spectrum and obtain evidence for a low-lying excited electronic state of Cs. The threshold photodetachment spectrometer used in this study is described in detail elsewhere.89’0 A beam of cold anion carbon clusters is generated in a laser vaporization/pulsed molecular beam source and is massselected using time of flight. The cluster of interest is then photodetached using a excimer-pumped tunable dye laser operating at 20 Hz, and electrons with near zero kinetic energy (ZEKE) are collected as a function of photon enery. The selective detection of the ZEKE electrons is done using the method developed by Mtiller-Dethlefs
TL;DR: In this paper, the interaction of evaporated copper overlayers, from 0.03 to 0.4 nm thick, with specific terminal functional groups of an organized molecular assembly (OMA) of HS(CH2)11CN formed on gold has been studied by x-ray photoelectron spectroscopy.
Abstract: The interaction of evaporated copper overlayers, from 0.03 to 0.4 nm thick, with specific terminal functional groups of an organized molecular assembly (OMA) of HS(CH2)11CN formed on gold has been studied by x‐ray photoelectron spectroscopy. For average copper coverages above 0.1 nm, the peak intensities show fair agreement with a model that assumes an increasing fraction of each increment of the deposited copper penetrates the OMA and resides at the OMA/Au interface. For lower coverages, a weak Cu(CN) interaction is indicated by shifts of the N 1s level and the C 1s high binding energy (HBE) shoulder to lower binding of as well as by the presence of a Cu 2p HBE shoulder.
TL;DR: In this paper, the binding energies for the 3D levels of As5+ and As3+ were determined to be 46.0 ± 0.17 eV and 44.6 ± 1.13 eV respectively, for oxides of arsenic being adsorbed on titania.
TL;DR: In this article, the 351 nm photoelectron spectra of Bi−2, Bi−3, and Bi−4 were recorded and the electron affinity was estimated from the onset of photodetachment to be 1.05(10) eV.
Abstract: We have recorded the 351 nm photoelectron spectra of Bi−2, Bi−3, and Bi−4. The spectrum of Bi−2 shows transitions to at least seven electronic states of Bi2 neutral, four of which are observed with vibrational resolution. Term energies, bond lengths, and vibrational frequencies are obtained for the anion ground state and for the first three excited states of Bi2. These results are compared to previous spectroscopic measurements and to the ab initio calculations presented in the accompanying paper. The photoelectron spectrum of Bi−3 reveals some of the electronic structure of Bi3 and the results are discussed in comparison to recent theoretical work. Adiabatic electron affinities are obtained for Bi2 [1.271(8) eV] and for Bi3 [1.60(3) eV]. The electron affinity of Bi4 is estimated from the onset of photodetachment to be 1.05(10) eV.
TL;DR: In this article, rotationally resolved photoelectron spectra of the OH radical were measured using (2+1) resonance enhanced multiphoton ionizationspectroscopy via the D 2 Σ^−(3pσ) and 3 3 Σ−(4sσ) Rydberg states.
Abstract: We have measured rotationally resolved photoelectron spectra of the OH radical using (2+1) resonance enhanced multiphoton ionizationspectroscopy via the D ^2Σ^−(3pσ) and 3 ^2Σ^−(4sσ) Rydberg states. For the D ^2Σ^−(3pσ) state, we observe primarily ΔN=even distributions of ionic rotational states, in contrast to the ΔN=odd distribution expected for ionization of a 3pσ Rydberg electron. The observations are described quantitatively by ab initio calculations which predict a Cooper minimum in the 3pσ→kπ(l=2) channel, whose occurrence determines the ΔN=even ion rotational distribution. In contrast, the 3 ^2Σ^−(4sσ) photoelectron spectra reveal a broad distribution in rotational levels, arising from greater l mixing in the higher Rydberg orbital and much weaker Cooper minima in the continuum.
TL;DR: In this article, the population of vibrational levels in the cation after one-color, two-photon ionization via various vibronic intermediate states of the neutral molecule has been investigated.
Abstract: The authors present multiphoton ionization photoelectron (PE) spectra of monofluoro-, chloro-, and -bromobenzene. The population of the vibrational levels in the cation after one-color, two-photon ionization via various vibronic intermediate states of the neutral molecule has been investigated. The observed structure has been assigned, and the frequencies of some vibrations in the ionic X-state were determined, providing new data for these molecular ions. Their results show that the PE spectra reflect Fermi resonances and Duschinsky rotations in the neutral intermediate states, allowing an interpretation of these states. The consequences of the results for neutral as well as ion spectroscopy are discussed.
TL;DR: In this article, the spin-orbit splitting of the IO ground state is determined to be −2091(40) cm−1, and the electron affinity of IO is found to be 2.378(5) eV.
Abstract: The 351 nm (hν=3.531 eV) photoelectron spectrum IO− shows transitions to two spin–orbit states of neutral IO. The electron affinity of IO is found to be 2.378(5) eV. Vibrational frequencies for the neutral (2Π1/2) and anion (1Σ+) states are reported. The spin–orbit splitting of the IO ground state is determined to be −2091(40) cm−1. Franck–Condon analysis of the IO vibrational progressions were used along with the previously determined 2Π3/2 molecular constants to obtain the equilibrium bond lengths of the anion (1Σ+) and neutral (2Π1/2) states.
TL;DR: In this article, the high resolution X-ray excited (hν = 1487 eV) valence photoelectron spectra of N2 and CO are presented, showing a rich line structure down to 65 eV binding energy due to electron correlation effects.
Abstract: The high resolution X-ray excited (hν = 1487 eV) valence photoelectron spectra of N2 and CO are presented. The spectra show a rich line structure down to 65 eV binding energy due to electron correlation effects. Several new structures are observed and new assignments are made from comparisons with calculations, monochromatized He II excited photoelectron spectra and resonance Auger electron spectra.
TL;DR: In this paper, a sensitive electron spectrometer has been used in study photoionization procer- ses in the region of the double-ionization threshold of helium.
Abstract: A sensitive electron spectrometer has been used in study photoionization procer- ses in the region of the double-ionization threshold of helium. Analysis of the cusp observed at the He2+ potential in a threshold photoelectron spectrum indicates that this structure would support the predictions of Wannier theory with a range of validity of 2.0+0.5 eV. Asymmetry parameters (p) have been obtained far near-threshold excitation of He'*(") satellite States up to and above n = IO at photoelectron snrrgirs of 0.14 and 0.25 eV. For n>6: B was found tn have a roughly constant value of about -0.5 and did not approach the predicted value of -1. Similarly, for the double-ionization process, fl is approximately constant at -0.4 in the energy range from 0.25 to 2.0 eV above the He'+ potential and doer not display the steep rise from p = -1 to positive values which is predicted to occur in this energy range.