The electronic structures of methane, ethane, ethylene and formaldehyde studied by high-resolution molecular photoelectron spectroscopy

Baker, A. D.; Baker, Carol S.; Brundle, C. R.; Turner, D. W.

doi:10.1016/0020-7381(68)85005-3

Cited by 228 publications

(50 citation statements)

References 34 publications

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“…Consequently, the weak, broad structure in the 1b 2 -ka 2 photoionization cross section of Fig. 5 can be attributed to the presence of pre-Rydberg 3da 2 orbitals in the continuum, 49 in accord with the results of Figs. 2 and 3.…”

Section: B 2 Excitation (Ip = 171)supporting

confidence: 79%

“…47 As expected, the lb 2 -ka 1 photoionization profile of 5 contains an a 1 a *(CO) resonance feature at -18 eV, in qualitative accord with the previously reported CI S-T results. 28 The very low intensity of the 1b 2 -npb 2 Rydberg series can be regarded as a consequence of the largely 2pY-npy nature of these transitions located at the c. m. By contrast, the 2b 2 (n)-nb 2 Rydberg series (Table II) is of medium intensity, presumably since the 2b 2 orbital is located primarily at the 0 end of the molecule. In spite of the fact that the lb 2 orbital contains a(CH) and rry(CO) bonding components, there is no evidence of a resonance transition in the 1b 2 -kb 2 photoionization continuum of Fig.…”

Section: B 2 Excitation (Ip = 171)mentioning

confidence: 92%

“…24 • 4 7 The continuum profiles shown in Fig. 6 for 4a 1 -kb 2 , ka~o and kb 1 excitation are evidently quite weak, and the kb 2 and ka 1 contributions do not contain the resonances common in the outer-orbital cross sections.…”

Section: A 1 Excitation (Jp =219 Ev)mentioning

confidence: 93%

“…(1)] obtained employing nonlocal potentials or configuration-interaction calculations. In the S-T technique, the spectral moments 40 N SN(-k)=Lk€.i\ k=0,1, ... ,2n-1, (2) id (n « N) are constructed, and these are employed in calculations of moment-theory spectra [E 1 (n), f 1 (n) ], i = 1, 2, ... , n, which satisfy…”

Section: Stiel Tjes-tchebycheff Techniquementioning

confidence: 99%

“…(15) for the 2b 2 , 1bt. and 5a 1 orbitals, 2 whereas Koopmans values are used for the 1b 2 and 4a 1 orbitals because of apparent uncertainties in the experimental assignments.…”

Section: V/mentioning

confidence: 99%

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Photoabsorption in formaldehyde: Intensities and assignments in the discrete and continuous spectral intervals

Langhoff

Orel

Rescigno

et al. 1978

The Journal of Chemical Physics

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Theoretical investigations of total and partial-channel photoabsorption cross sections in molecular formaldehyde are reported employing the Stieltjes-Tchebycheff (s-T) technique and separated-channel static-exchange (!YO) calculations. Vertical one-electron dipole spectra for the 2b 2 (n), lb 1(7T), 5a 1(a), I b 2 , and 4a 1 canonical molecular orbitals are obtained using Hartree-Fock frozen-core functions and large basis sets of compact and diffuse normalizable Gaussians to describe the photoexcited and ejected electrons. The calculated discrete excitation spectra provide reliable zeroth-order approximations to both valence and Rydberg transitions, and, in particular, the 2b 2 (n)-msa 1 , npa 1 , npb 2 , and nda 2 IVO spectra are in excellent accord with recent experimental assignments and available intensity measurements. Convergent (S-T) photoionization cross sections in the static-exchange (IVO) approximation are obtained for the 15 individual partial channels associated with ionization of the five occupied molecular orbitals considered. Resonance features in many of the individual-channel photoionization cross sections are attributed to contributions frorn valencelike a 1 a*(CO), a 1 a*(CH), and b 2 a*(CH)/7Ty *(CO) molecular orbitals that appear in the photoionization continua, rather than in the corresponding one-electron discrete spectral intervals. The vertical electronic cross sections for 1 A 1 -+ 1 B 1 , 1 B 2 , and 1 A 1 excitations are in generally good accord with previously reported CI (s-T) predictions of continuum orbital assignments and intensities, although some discrepancies due to basis-set differences are present in the 1 B 1 and 1 B 2 components, and larger discrepancies apparently due to channel coupling are present in the 1 A 1 -+ 1 A 1 cross section. Partialchannel vertical electronic cross sections for the production of the five lowest parent-ion electronic states are found to be in general agreement with the results of very recent synchrotron-radiation photoelectron branching-ratio measurements in the 20 to 30 eV excitation energy interval. Most important in this connection is the tentative verification of the predicted orderings in intensities of the partial-channel cross sections, providing support for the presence of a strong ka 1

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Section: B 2 Excitation (Ip = 171)supporting

confidence: 79%

Section: B 2 Excitation (Ip = 171)mentioning

confidence: 92%

Section: A 1 Excitation (Jp =219 Ev)mentioning

confidence: 93%

Section: Stiel Tjes-tchebycheff Techniquementioning

confidence: 99%

“…(15) for the 2b 2 , 1bt. and 5a 1 orbitals, 2 whereas Koopmans values are used for the 1b 2 and 4a 1 orbitals because of apparent uncertainties in the experimental assignments.…”

Section: V/mentioning

confidence: 99%

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