The role of initial and final states in molecular spectroscopies

Tino Kirchhuebel, Oliver L A Monti Masel, Toshiaki Munakata, Satoshi Kera, Roman Forker, Torsten Fritz

Research output: Contribution to journalArticle

Abstract

Interpreting experimental spectra of thin films of organic semiconductors is challenging, and understanding the relationship between experimental data obtained by different spectroscopic techniques requires a careful consideration of the initial and final states for each process. The discussion of spectroscopic data is frequently mired in confusion that originates in overlapping terminology with however distinct meaning in different spectroscopies. Here, we present a coherent framework that is capable of treating on equal footing most spectroscopies commonly used to investigate thin films of organic semiconductors. We develop a simple model for the expected energy level positions, as obtained by common spectroscopic techniques, and relate them to the energies of molecular states. Molecular charging energies in photoionization processes, as well as adsorption energies and the screening of molecular charges due to environmental polarization, are taken into account as the main causes for shifts of the measured spectroscopic features. We explain the relationship between these quantities, as well as with the transport gap, the optical gap and the exciton binding energy. Our considerations serve as a model for weakly interacting systems, e.g., various organic molecular crystals, where wave function hybridizations between adjacent molecules are negligible.

Original languageEnglish (US)
Pages (from-to)12730-12747
Number of pages18
JournalPhysical Chemistry Chemical Physics
Volume21
Issue number24
DOIs
StatePublished - Jan 1 2019

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Molecular spectroscopy
molecular spectroscopy
Semiconducting organic compounds
organic semiconductors
Spectroscopy
Molecular crystals
Thin films
Photoionization
Terminology
Wave functions
Binding energy
Electron energy levels
Screening
terminology
confusion
Polarization
thin films
Adsorption
spectroscopy
Molecules

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

The role of initial and final states in molecular spectroscopies. / Kirchhuebel, Tino; Monti Masel, Oliver L A; Munakata, Toshiaki; Kera, Satoshi; Forker, Roman; Fritz, Torsten.

In: Physical Chemistry Chemical Physics, Vol. 21, No. 24, 01.01.2019, p. 12730-12747.

Research output: Contribution to journalArticle

Kirchhuebel, T, Monti Masel, OLA, Munakata, T, Kera, S, Forker, R & Fritz, T 2019, 'The role of initial and final states in molecular spectroscopies', Physical Chemistry Chemical Physics, vol. 21, no. 24, pp. 12730-12747. https://doi.org/10.1039/c8cp07318j
Kirchhuebel, Tino ; Monti Masel, Oliver L A ; Munakata, Toshiaki ; Kera, Satoshi ; Forker, Roman ; Fritz, Torsten. / The role of initial and final states in molecular spectroscopies. In: Physical Chemistry Chemical Physics. 2019 ; Vol. 21, No. 24. pp. 12730-12747.
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