Symmetry-resolved C and O<i>K</i>-shell photoabsorption spectra of free CO molecules

Shigemasa, E.; Hayaishi, T; Sasaki, Taizo; Yagishita, Akira

doi:10.1103/physreva.47.1824

Cited by 75 publications

(51 citation statements)

References 30 publications

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“…For vЈ = 0, the agreement between theory and experiment is reasonably good, and two kinds of the vibrational wave functions give practically identical answers. Some discrepancy at about 6 -10 eV photoelectron energy may be related to the contribution of doubly excited states (see [21] for experimental evidence) not taken into account in the RCHF(0.5) approximation. For vЈ = 1, the theoretical curves are somewhat higher than the experimental points at all energies.…”

Section: Resultsmentioning

confidence: 99%

Interplay of different partial waves on vibrationally resolved photoionization of the OKshell of the CO molecule

et al. 2004

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The asymmetry parameter ␤ for the O K shell photoemission of the CO molecule has been measured for different vibrational states of the residual ion. The corresponding calculations performed by us in the relaxed core Hartree-Fock approximation are in qualitative agreement with the experiment. From the analysis of theoretical data, we made the conclusion that the variation of ␤ with the vibrational quantum number is connected with different dependences of the dipole matrix elements in the s, d, and f channels on the internuclear distance R in the * shape resonance.

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Section: Resultsmentioning

confidence: 99%

Interplay of different partial waves on vibrationally resolved photoionization of the OKshell of the CO molecule

et al. 2004

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“…Measurements of the corresponding alignment in the core-level shape resonances of CO were not performed until very recently [6] and even these measurements were not absolutely calibrated. Therefore it was the objective of this study to determine in a first step the molecular alignment p m of the core excited state and afterwards to examine the intrinsic anisotropy c a of the Auger decay.…”

Section: Observation Of Nonisotropic Auger Angular Distribution In Thmentioning

confidence: 99%

Observation of nonisotropic Auger angular distribution in the C(1s) shape resonance of CO

et al. 1993

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Angle-resolved high-resolution C(KVV) Auger spectra of CO were taken in the vicinity of the CO^y) cr* shape resonance. These spectra show clear evidence for the theoretically predicted anisotropic Kshell Auger emission in molecules. Complementary results from angle-resolved photoion spectroscopy show that the small size of the observed effect is, besides the varying intrinsic anisotropy of the Auger decay, also due to a smaller anisotropy in the primary absorption process than originally predicted but in good agreement with more recent calculations. Contrary to this, satellite Auger transitions show unexpectedly large anisotropics.PACS numbers: 32.80.Hd Atomic AT-shell vacancies are isotropic and hence Auger decay of these vacancies is also isotropic. Molecules are different in this respect; they are supposed, for symmetry reasons, to exhibit anisotropic behavior. This Auger anisotropy is the direct result of anisotropic absorption, i.e., the exciting radiation in the a-* TT* excitation selects molecules with an axis oriented preferentially perpendicular to the electric vector because the electrons excited in this process are finally in a state of n symmetry. In contrast, a a-* cr* transition prefers parallel orientation due to the a symmetry of the excited electrons. This behavior turned out to be the key aspect for a wide field of applications such as near edge x-ray absorption fine-structure (NEXAFS) and symmetry-dependent molecular spectroscopy.However, since the prediction of those anisotropic ATshell Auger angular distributions in the Is a* shape resonances originating from intramolecular scattering in the \s continuum of CO and N2 by Dill and co-workers [1,2] more than a decade ago, all experimental results obtained for continuum resonances seemed to contradict this general prediction [3,4]. The question arose whether this was due to insufficient alignment of the molecules by the photoabsorption process above threshold or a result of vanishing intrinsic anisotropy of the subsequent Auger decay. Both possibilities seemed to be somewhat unlikely because the alignment creation is the result of very general physical properties of a molecule-potential behavior and symmetry-in conjunction with the dipole selection rules, whereas the intrinsic anisotropy had shown up to vary over all allowed values, particularly in atoms, but without showing any tendency to center around zero. Therefore, independent direct alignment measurements were undertaken and the situation became even more puzzling after strong molecular alignment within the Is cr* shape resonances of N2 which was confirmed via angle-resolved photoion spectroscopy [5] according to the prediction of Dill et al [2].Measurements of the corresponding alignment in the core-level shape resonances of CO were not performed until very recently [6] and even these measurements were not absolutely calibrated. Therefore it was the objective of this study to determine in a first step the molecular alignment p m of the core excited state and afterwards to examine the ...

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“…2. The curves show a possible reconstruction of the partial cross sections from the condition to correctly reproduce the cross section measured in [4]. The contributions of d and f partial waves could not be extracted unambiguously having only one point in the resonance; therefore their sum is also presented which is defined with much higher confidence.…”

mentioning

confidence: 95%

“…This means that the molecular field can support a quasibound f state oriented along the molecular axis. The fact that the resonances appear only in s channels has recently been proved experimentally for several molecules [3,4] by measuring the partial s and p channel cross sections separately using angle-resolved photoion spectroscopy.…”

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Direct Determination of Partial Wave Contributions in theσ*Shape Resonance of CO Molecules

Shigemasa¹,

Adachi

Soejima

et al. 1998

Phys. Rev. Lett.

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The first complete experiment for the C K-shell of CO molecules in the region of the s ‫ء‬ shape resonance has been performed by detecting photoelectrons in coincidence with fragment ions. Four ratios of dipole matrix elements and four phase shift differences have been extracted from the experimental data. Their analyses show that, in the s ‫ء‬ shape resonance due to the l mixing, d and f partial waves give the main contribution to the cross section, and f and g waves give the main contribution to a rapid increase of phase shift by p. [S0031-9007(97)

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Symmetry-resolved C and OK-shell photoabsorption spectra of free CO molecules

Cited by 75 publications

References 30 publications

Interplay of different partial waves on vibrationally resolved photoionization of the OKshell of the CO molecule

Interplay of different partial waves on vibrationally resolved photoionization of the OKshell of the CO molecule

Observation of nonisotropic Auger angular distribution in the C(1s) shape resonance of CO

Direct Determination of Partial Wave Contributions in theσ*Shape Resonance of CO Molecules

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