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Determination of electronic energy levels of molecules by 90° low energy electron scattering


Wei, Pax Samuel Pin (1968) Determination of electronic energy levels of molecules by 90° low energy electron scattering. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/T6F4-S527.


A review of the theory of electron scattering indicates that low incident beam energies and large scattering angles are the favorable conditions for the observation of optically forbidden transitions in atoms and molecules.

An apparatus capable of yielding electron impact spectra at 90° with incident electron beam energies between 30 and 50 electron volts is described. The resolution of the instrument is about 1 electron volt.

Impact spectra of thirteen molecules have been obtained. Known forbidden transitions to the helium 23S, the hydrogen b3Ʃ+u, the nitrogen A3Ʃ+u, B3πg, a’πg, and C3πu, the carbon monoxide a3π, the ethylene ᾶ3B1u, and the benzene ᾶ3B1u states from the corresponding ground states have been observed.

In addition, singlet-triplet vertical transitions in acetylene, propyne, propadiene, norbornadiene and quadricyclene, peaking at 5.9, 5.9, 4.5, 3.8, and 4.0 ev (±0.2 ev), respectively, have been observed and assigned for the first time.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Chemistry
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Kuppermann, Aron
Thesis Committee:
  • Unknown, Unknown
Defense Date:10 October 1967
Record Number:CaltechTHESIS:01112016-083235093
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9364
Deposited On:11 Jan 2016 18:31
Last Modified:09 Nov 2022 19:20

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