3 research outputs found
Elastic scattering and vibrational excitation for electron impact on para-benzoquinone
FUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICO - CNPQWe report on theoretical elastic and experimental vibrational-excitation differential cross sections (DCSs) for electron scattering from para-benzoquinone (C6H4O2), in the intermediate energy range 15-50 eV. The calculations were conducted with two different theoretical methodologies, the Schwinger multichannel method with pseudopotentials (SMCPP) and the independent atom method with screening corrected additivity rule (IAM-SCAR) that also now incorporates a further interference (I) term. The SMCPP with N energetically open electronic states (N-open) at the static-exchange-plus-polarisation (N(open)ch-SEP) level was used to calculate the scattering amplitudes using a channel coupling scheme that ranges from 1ch-SE up to the 89ch-SEP level of approximation. We found that in going from the 38ch-SEP to the 89ch-SEP, at all energies considered here, the elastic DCSs did not change significantly in terms of both their shapes and magnitudes. This is a good indication that our SMCPP 89ch-SEP elastic DCSs are converged with respect to the multichannel coupling effect for the investigated intermediate energies. While agreement between our IAM-SCAR+I and SMCPP 89ch-SEP computations improves as the incident electron energy increases from 15 eV, overall the level of accord is only marginal. This is particularly true at middle scattering angles, suggesting that our SCAR and interference corrections are failing somewhat for this molecule below 50 eV. We also report experimental DCS results, using a crossed-beam apparatus, for excitation of some of the unresolved ("hybrid") vibrational quanta (bands I-III) of para-benzoquinone. Those data were derived from electron energy loss spectra that were measured over a scattered electron angular range of 10 degrees-90 degrees and put on an absolute scale using our elastic SMCPP 89ch-SEP DCS results. The energy resolution of our measurements was similar to 80 meV, which is why, at least in part, the observed vibrational features were only partially resolved. To the best of our knowledge, there are no other experimental or theoretical vibrational excitation results against which we might compare the present measurements.14724112FUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICO - CNPQFUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICO - CNPQ2014/10012-92015/23792-5305672/2014-2This study has been partially supported by the Spanish Ministry MINECO (Project No. FIS2016-80440), COST (CM301 Action) and ITN-Marie Curie (No. ARGENT-608163) European Union programmes. M.A.P.L., M.T.do.N.V. (Grant No. 305672/2014-2), R.F.C., and M.H.F.B. all acknowledge financial support from CNPq, while F.K. (Grant No. 2015/23792-5) and M.T.do.N.V. (Grant No. 2014/10012-9) also thank FAPESP for financial support. Finally, M.J.B. (No. DP160102787) and R.D.W. acknowledge the Australian Research Council for funding
Elastic scattering and vibrational excitation for electron impact on para-benzoquinone
12 pags., 6 figs., 4 tabs.We report on theoretical elastic and experimental vibrational-excitation differential cross sections
(DCSs) for electron scattering from para-benzoquinone (C6H4O2), in the intermediate energy
range 15â50 eV. The calculations were conducted with two different theoretical methodologies, the
Schwinger multichannel method with pseudopotentials (SMCPP) and the independent atom method
with screening corrected additivity rule (IAM-SCAR) that also nowincorporates a further interference
(I) term. The SMCPP with N energetically open electronic states (Nopen) at the static-exchange-pluspolarisation
(Nopench-SEP) level was used to calculate the scattering amplitudes using a channel
coupling scheme that ranges from 1ch-SE up to the 89ch-SEP level of approximation.We found that
in going from the 38ch-SEP to the 89ch-SEP, at all energies considered here, the elastic DCSs did not
change significantly in terms of both their shapes and magnitudes. This is a good indication that our
SMCPP 89ch-SEP elastic DCSs are converged with respect to the multichannel coupling effect for the
investigated intermediate energies. While agreement between our IAM-SCAR+I and SMCPP 89ch-
SEP computations improves as the incident electron energy increases from 15 eV, overall the level
of accord is only marginal. This is particularly true at middle scattering angles, suggesting that our
SCAR and interference corrections are failing somewhat for this molecule below50 eV.We also report
experimental DCS results, using a crossed-beam apparatus, for excitation of some of the unresolved
(âhybridâ) vibrational quanta (bands IâIII) of para-benzoquinone. Those data were derived from electron
energy loss spectra that were measured over a scattered electron angular range of 10â90 and
put on an absolute scale using our elastic SMCPP 89ch-SEP DCS results. The energy resolution of
our measurements was s80 meV, which is why, at least in part, the observed vibrational features were
only partially resolved. To the best of our knowledge, there are no other experimental or theoretical
vibrational excitation results against which we might compare the present measurements.This study has been partially supported by the
Spanish Ministry MINECO (Project No. FIS2016-80440),
COST (CM301 Action) and ITN-Marie Curie (No.
ARGENT-608163) European Union programmes. M.A.P.L.,
M.T.do.N.V. (Grant No. 305672/2014-2), R.F.C., and
M.H.F.B. all acknowledge financial support from CNPq, while
F.K. (Grant No. 2015/23792-5) and M.T.do.N.V. (Grant No.
2014/10012-9) also thank FAPESP for financial support.
Finally, M.J.B. (No. DP160102787) and R.D.W. acknowledge
the Australian Research Council for funding.Peer Reviewe
Elastic scattering and vibrational excitation for electron impact on para-IT-benzoquinone
We report on theoretical elastic and experimental vibrational-excitation differential cross sections (DCSs) for electron scattering from para-benzoquinone (C6H4O2), in the intermediate energy range 15-50 eV. The calculations were conducted with two different theoretical methodologies, the Schwinger multichannel method with pseudopotentials (SMCPP) and the independent atom method with screening corrected additivity rule (IAM-SCAR) that also now incorporates a further interference (I) term. The SMCPP with N energetically open electronic states (N-open) at the static-exchange-plus-polarisation (N(open)ch-SEP) level was used to calculate the scattering amplitudes using a channel coupling scheme that ranges from 1ch-SE up to the 89ch-SEP level of approximation. We found that in going from the 38ch-SEP to the 89ch-SEP, at all energies considered here, the elastic DCSs did not change significantly in terms of both their shapes and magnitudes. This is a good indication that our SMCPP 89ch-SEP elastic DCSs are converged with respect to the multichannel coupling effect for the investigated intermediate energies. While agreement between our IAM-SCAR+I and SMCPP 89ch-SEP computations improves as the incident electron energy increases from 15 eV, overall the level of accord is only marginal. This is particularly true at middle scattering angles, suggesting that our SCAR and interference corrections are failing somewhat for this molecule below 50 eV. We also report experimental DCS results, using a crossed-beam apparatus, for excitation of some of the unresolved ("hybrid") vibrational quanta (bands I-III) of para-benzoquinone. Those data were derived from electron energy loss spectra that were measured over a scattered electron angular range of 10 degrees-90 degrees and put on an absolute scale using our elastic SMCPP 89ch-SEP DCS results. The energy resolution of our measurements was similar to 80 meV, which is why, at least in part, the observed vibrational features were only partially resolved. To the best of our knowledge, there are no other experimental or theoretical vibrational excitation results against which we might compare the present measurements. Published by AIP Publishing