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Title: Determination of ground and excited state dipole moments via electronic Stark spectroscopy: 5-methoxyindole

The dipole moments of the ground and lowest electronically excited singlet state of 5-methoxyindole have been determined by means of optical Stark spectroscopy in a molecular beam. The resulting spectra arise from a superposition of different field configurations, one with the static electric field almost parallel to the polarization of the exciting laser radiation, the other nearly perpendicular. Each field configuration leads to different intensities in the rovibronic spectrum. With an automated evolutionary algorithm approach, the spectra can be fit and the ratio of both field configurations can be determined. A simultaneous fit of two spectra with both field configurations improved the precision of the dipole moment determination by a factor of two. We find a reduction of the absolute dipole moment from 1.59(3) D to 1.14(6) D upon electronic excitation to the lowest electronically excited singlet state. At the same time, the dipole moment orientation rotates by 54{sup ∘} showing the importance of the determination of the dipole moment components. The dipole moment in the electronic ground state can approximately be obtained from a vector addition of the indole and the methoxy group dipole moments. However, in the electronically excited state, vector addition completely fails to describe the observedmore » dipole moment. Several reasons for this behavior are discussed.« less
Authors:
; ;  [1] ;  [2]
  1. Institut für Physikalische Chemie, Heinrich-Heine-Universität, D-40225 Düsseldorf (Germany)
  2. Institute for Molecules and Materials, Radboud University, NL-6525 AS Nijmegen (Netherlands)
Publication Date:
OSTI Identifier:
22493687
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 144; Journal Issue: 4; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTROSCOPY; DIPOLE MOMENTS; ELECTRIC FIELDS; EXCITATION; EXCITED STATES; GROUND STATES; INDOLES; LASER RADIATION; METHOXY RADICALS; MOLECULAR BEAMS; ORIENTATION; POLARIZATION; STARK EFFECT