Vibrationally resolved photoelectron angular distributions and branching ratios for the carbon dioxide molecule in the wavelength region 685–795 Å

West, John B.; Hayes, M. A.; Siggel, M. R. F.; Dehmer, Joseph L.; Dehmer, Patricia M.; Parr, Albert C.; Hardis, Jonathan E.

doi:10.1063/1.471249

Cited by 10 publications

(10 citation statements)

References 25 publications

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“…The same shift is also seen clearly in the b͑ 1 P͒ data. The experimental observation of the energy shift of the b minimum relative to the resonance energy is not unique to date, since it has been measured and discussed earlier in the case of nitrogen and carbon dioxide molecules [21,22]. Also, one early measurement mentions the qualitative observation of such a shift for argon and xenon atoms [23].…”

Section: (Received 2 July 1999)mentioning

confidence: 99%

Angle-Resolved Photoelectron Spectrometry Studies of the Autoionization of the2s22p2P<

et al. 2000

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We have measured the angle-resolved energy dependence of the electrons emitted over the energy range of the triply excited 2s 2 2p 2 P lithium resonance using synchrotron radiation. We have also calculated the behavior of the angular distribution parameter b using the R-matrix approximation. Experimental and theoretical results are in good agreement and show deep minima in the 1s2p 1, 3 P ionic channels. The energy at which the minima occur does not coincide with the resonance energy, but is shifted towards higher energy. PACS numbers: 32.80.Hd, 32.80.Fb In this Letter, we present the results of a new experiment investigating the angular distribution of electrons emitted in autoionization of the lowest-energy triply excited state of atomic lithium. We made a critical comparison of the data with the results of advanced Rmatrix calculations performed in order to interpret the energy behavior of the angular distribution parameter b. Photons from the Advanced Light Source (ALS) photoexcited the 2s 2 2p 2 P hollow lithium state both on and off resonance. The electrons emitted were angularly analyzed with a cylindrical mirror analyzer (CMA) electron spectrometer. The experimental results reveal a pronounced energy dependence of the angular distribution parameter b in the Li 1 1s2p 1, 3 P´l satellite channels, in good agreement with theoretical prediction. Both experiment and theory show that the minima in the b profiles occur on the high energy side of the resonance.From the early 1960s [1], doubly excited states of helium have provided the ideal case for studying the threebody system of two correlated electrons interacting with the nucleus. Recent investigation on this system achieved very high resolution photoabsorption [2] and photoelectron [3] measurements. Experimental studies of helium helped to establish the theory of autoionization [4] and to introduce a new set of quantum numbers [5] describing doubly excited states in two-electron systems. The challenge to extend these investigations to triply excited states in neutral lithium started with their observation in collision experiments [6]. Subsequently, photoexcitation experiments [7][8][9][10] allowed accurate measurements of the excitation energies, identification of many of the resonances, and the determination of some partial photoionization cross sections for autoionization into the lowest continua of the Li 1 ion. Most recently, the investigation of this system received strong impetus from the use of a third generation storage ring delivering high-brightness photon beams in the photon energy range (140-200 eV). Highresolution partial cross sections were determined for triple excitation of lithium atoms [11,12] including a classification of many of the states into Rydberg series. The lowestenergy triply excited state in which all three electrons have the same principal quantum number ͑n 3͒ was also measured [13,14]. Theoretical calculations involving various approximations (R matrix [10-13], saddle point [15]) were carried out providing good agreement w...

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Section: (Received 2 July 1999)mentioning

confidence: 99%

Angle-Resolved Photoelectron Spectrometry Studies of the Autoionization of the2s22p2P<

et al. 2000

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“…In conclusion, the results shown in this section indicate that the presence of strong autoionizing resonances, such as the Henning series, significantly affects the distribution of vibrational populations of the ion. A similar analysis has been done before by Parr et al, 59 and West et al, 10 concentrating on the ionic ground state. In particular, Parr et al followed the behaviour of branching ratios and asymmetry parameters of vibrational states of the X band around three resonances.…”

Section: U +mentioning

confidence: 57%

“…The exact assignment of the Tanaka-Ogawa series is still under debate, but theoretical considerations point to a ndδ g configuration. 10 Because of these uncertainties the series has been labelled with a running number m instead of the principal quantum number n in Ref. 8, which we have carried over in Figure 4.…”

Section: B Cross Section Branching Ratios Asymmetry Parameters Anmentioning

confidence: 99%

Photoelectron imaging of XUV photoionization of CO2 by 13–40 eV synchrotron radiation

Furch

Birkner

Jungmann

et al. 2013

The Journal of Chemical Physics

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Valence band photoionization of CO 2 has been studied by photoelectron spectroscopy using a velocity map imaging spectrometer and synchrotron radiation. The measured data allow retrieving electronic and vibrational branching ratios, vibrationally resolved asymmetry parameters, and the total electron yield which includes multiple strong resonances. Additionally, the spectrum of low kinetic energy electrons has been studied in the resonant region, and the evolution with photon energy of one of the forbidden transitions present in the slow photoelectrons spectrum has been carefully analyzed, indicating that in the presence of auto-ionizing resonances the vibrational populations of the ion are significantly redistributed.

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“…In a previous publication [ 15 ], we gave results for the branching ratios and asymmetry parameters for CO 2 in the wavelength region of 685 Å to 795 Å for some of the autoionizing lines in the Tanaka-Ogawa (TO) series, the Henning sharp (s) and diffuse (d) series. However, we did not publish the extensive additional data we had obtained as a result of analyzing the photoelectron spectra taken in this wavelength region.…”

Section: Introductionmentioning

confidence: 99%

“…In our previous publication concerning the branching ratios and asymmetry parameters in this wavelength region we presented only a small subset of the data we have on CO 2 in this wavelength region. We present here a detailed explanation of the data accumulation techniques and a complete discussion of the analysis of the data that was not possible in the shorter summary of this work [ 15 ]. To be consistent with the earlier NIST publications on this topic, we have used the unit of the Angstrom to describe the wavelength scale used for these experiments even though this unit is no longer sanctioned as an acceptable metric system unit.…”

Section: Introductionmentioning

confidence: 99%

Vibrational branching ratios and asymmetry parameters in the photoionization of CO2 in the region between 650 angstrom and 840 angstrom

Parr¹,

West²,

King³

et al. 2001

J. Res. Natl. Inst. Stand. Technol.

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The vibrational branching ratios and asymmetry parameters for CO2 have been determined in the wavelength region of 650 Å to near the ionization onset at about 840 Å. The study was performed using synchrotron radiation from the Daresbury storage ring that was dispersed with a 5 m grating monochomator that afforded resolution of 0.1 Å to 0.2 Å. This resolution allowed the study of the branching ratios and asymmetry parameters with enough detail to see the changes in the parameters within the pronounced autoionization structure in CO2 in this wavelength region. While the electron spectrometer resolution was not sufficient to resolve the spin orbit and Renner-Teller splitting in the photoelectron spectra, we are able to fit the data with a model that identifies the major structure in terms of the symmetric stretch and elements of the asymmetric stretch and bending modes. A calculation of the expected relative vibrational excitations based upon the Franck-Condon principle clearly showed non-Franck-Condon behavior in some of the vibrational-electronic transitions.

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Vibrationally resolved photoelectron angular distributions and branching ratios for the carbon dioxide molecule in the wavelength region 685–795 Å

Cited by 10 publications

References 25 publications

Angle-Resolved Photoelectron Spectrometry Studies of the Autoionization of the2s22p2P<

Angle-Resolved Photoelectron Spectrometry Studies of the Autoionization of the2s22p2P<

Photoelectron imaging of XUV photoionization of CO2 by 13–40 eV synchrotron radiation

Vibrational branching ratios and asymmetry parameters in the photoionization of CO2 in the region between 650 angstrom and 840 angstrom

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