Electronic structures of organic salts (DI-DCNQI) 2 M(M Cu and Ag) using photoelectron spectromicroscopy

The electronic structures of organic salts (DI-DCNQI) 2 M with M Cu and Ag, where DI-DCNQI is 2,5-diiodo-N,N # - dicyanoquinonediimine, were studied using photoelectron spectromicroscopy at various photon energies. From the photon energy dependence of the photoionization cross-section, the atomic orbital characters of the observed spectral features were determined. For both (DI-DCNQI) 2 Cu and (DI-DCNQI) 2 Ag, the C and N 2p states originating in the cyano group and the quinone ring are located at # 4.0 and # 6.5 eV, respectively. The Cu 3d states for (DI-DCNQI) 2 Cu and the Ag 4d states for (DI-DCNQI) 2 Ag are located at # 3.2 and # 5.2 eV, respectively. This indicates that the p#--d hybridization at the Fermi level between the M ions and the N atoms of the DCNQI columns is larger for (DI-DCNQI) 2 Cu than for (DI-DCNQI) 2 Ag. The reason for the difference in the electronic structure between (DI-DCNQI) 2 Cu and (DMe-DCNQI) 2 Cu is also discussed. # 1999 Elsevier Science Ltd. All rights reserved

Study of magnetic linear dichroism (MLD) for different thickness of Ni thin film grown on ferromagnetic Co (001) in element specific photoemission

Proceedings of the 1998 12th International Conference on Vacuum Ultraviolet Radiation Physics (VUV-12) --3 August 1998 through 7 August 1998 -- San Francisco, CA, USA --The magnetic linear dichroism (MLD) was used to study the magnetic properties of Ni-ultrathin film grown on ferromagnetic substrate Co(001). The MLD in photoemission has been measured for either the valence Ni3d states around the Ni3p threshold or 3p core level. Our dichroism measurements of the valence Ni3d states conclude that the resonance effect is present on MLD for `6 eV-satellite' in the valence band photoemission whereas the main valence band peak shows nearly same MLD signal for the both on and off resonance. It is shown for the thinner film that the dichroism from Ni and Co3p core levels shows same sign with each other. This means that the Ni and Co are ferromagnetically coupled.Ministry of Education, Culture, Sports, Science and TechnologyThe authors would like to thank the staff members of the UVSOR facility for their help during the experiments. This work is partly supported by the Grant-in-Aid for Scientific Research from the Ministry of Education, Science, Sports and Culture in Japan. YU received financial support from the Scientific and Technical Research Council of Turkey (TUBITAK)

Electronic structures of organic salts (DI-DCNQI)2M (M = Cu and Ag) using photoelectron spectromicroscopy

The electronic structures of organic salts (DI-DCNQI)2M with M = Cu and Ag, where DI-DCNQI is 2,5-diiodo-N,N'-dicyanoquinonediimine, were studied using photoelectron spectromicroscopy at various photon energies. From the photon energy dependence of the photoionization cross-section, the atomic orbital characters of the observed spectral features were determined. For both (DI-DCNQI)2Cu and (DI-DCNQI)2Ag, the C and N 2p states originating in the cyano group and the quinone ring are located at approximately 4.0 and approximately 6.5 eV, respectively. The Cu 3d states for (DI-DCNQI)2Cu and the Ag 4d states for (DI-DCNQI)2Ag are located at approximately 3.2 and approximately 5.2 eV, respectively. This indicates that the p?-d hybridization at the Fermi level between the M ions and the N atoms of the DCNQI columns is larger for (DI-DCNQI)2Cu than for (DI-DCNQI)2Ag. The reason for the difference in the electronic structure between (DI-DCNQI)2Cu and (DMe-DCNQI)2Cu is also discussed.Ministry of Education, Culture, Sports, Science and Technology Institute for Molecular ScienceThis work is partially supported by a Grant-in-Aid for Scientific Research from Ministry of Education, Science, Sports and Culture, and supported by the Joint Studies Program (1997–1999) of the Institute for Molecular Science, UVSOR

Photoemission study of mixed-valent Tm-monochalcogenides: Evidence of electron-correlation effect in different Tm-core levels

Systematic results of the photoemission spectra for different core levels such as, Tm 4p, 5p and 3d in the mixed valent Tm-monochalcogenides (TmS, TmSe and TmTe) obtained by both experimentally and theoretically are reported. The effects of the electron-electron correlation due to the interaction between core-holes and 4 f-electrons or the interaction between different configurations are considered to explain the spectral features, depending on the principal (n) and orbital quantum numbers of the core levels. Any sharp peak corresponding to a spin-orbital term is not observed especially from the n = 4 states. Instead, the multiplet structures are dominantly observed, and the physical identity of the spin-orbital peaks is totally or partially dissolved into the multiplets. Moreover, the electron-correlation effect is found to be dependent on the valence components (Tm2+ and Tm3+). In the case of the Tm 4p core level, in which the principal quantum number is identical with the valence 4 f, the correlation effect is stronger, and the configuration interaction is therefore considered to explain the spectral features. The photoemission spectra for the shallow core level Tm 5p also show the effect of electron correlation, but weaker than that for Tm 4p. This has been confirmed by the resonant photoemission spectroscopy taken at Tm 4d-4f absorption edges. In addition, the feature of Tm 3d photoemission spectra is discussed. All the experimental spectra are compared with the calculated ones. It is therefore understood that the electron correlation effect plays an important role on determining the various features in Tm 4p, 5p and 3d photoemission spectra. © 2003 The Physical Society of Japan

Journal of Electron Spectroscopy and Related Phenomena 101--103 (1999) 257--262

The magnetic linear dichroism (MLD) was used to study the magnetic properties of Ni-ultrathin film grown on ferromagnetic substrate Co(001). The MLD in photoemission has been measured for either the valence Ni3d states around the Ni3p threshold or 3p core level. Our dichroism measurements of the valence Ni3d states conclude that the resonance effect is present on MLD for `6 eV-satellite' in the valence band photoemission whereas the main valence band peak shows nearly same MLD signal for the both on and off resonance. It is shown for the thinner film that the dichroism from Ni and Co3p core levels shows same sign with each other. This means that the Ni and Co are ferromagnetically coupled. 1999 Elsevier Science B.V. All rights reserved

Electronic structures of organic salts (DI-DCNQI)2M (M=Cu and Ag) using photoelectron spectromicroscopy

The electronic structures of organic salts (DI-DCNQI)2M with M = Cu and Ag, where DI-DCNQI is 2,5-diiodo-N,N'-dicyanoquinonediimine, were studied using photoelectron spectromicroscopy at various photon energies. From the photon energy dependence of the photoionization cross-section, the atomic orbital characters of the observed spectral features were determined. For both (DI-DCNQI)2Cu and (DI-DCNQI)2Ag, the C and N 2p states originating in the cyano group and the quinone ring are located at approximately 4.0 and approximately 6.5 eV, respectively. The Cu 3d states for (DI-DCNQI)2Cu and the Ag 4d states for (DI-DCNQI)2Ag are located at approximately 3.2 and approximately 5.2 eV, respectively. This indicates that the p?-d hybridization at the Fermi level between the M ions and the N atoms of the DCNQI columns is larger for (DI-DCNQI)2Cu than for (DI-DCNQI)2Ag. The reason for the difference in the electronic structure between (DI-DCNQI)2Cu and (DMe-DCNQI)2Cu is also discussed.Ministry of Education, Culture, Sports, Science and Technology Institute for Molecular ScienceThis work is partially supported by a Grant-in-Aid for Scientific Research from Ministry of Education, Science, Sports and Culture, and supported by the Joint Studies Program (1997–1999) of the Institute for Molecular Science, UVSOR