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Updated: May 30, 2026

Using Cyclic Voltammetry, UV-Vis-NIR, and EPR Spectroelectrochemistry to Analyze Organic Compounds
Published on: October 18, 2018
C6H and C6D: electronic spectra and Renner-Teller analysis.
Dongfeng Zhao1, Mohammad Ali Haddad, Harold Linnartz
1Institute for Lasers, Life, and Biophotonics, VU University Amsterdam, De Boelelaan 1081, NL 1081HV Amsterdam, The Netherlands. d.zhao@vu.nl
High-resolution spectroscopy of C6H and C6D reveals new details about their electronic states. The study analyzes vibronic hot bands and the Renner-Teller effect, determining the excitation energy of a key vibronic state.
Area of Science:
- Molecular Spectroscopy
- Physical Chemistry
- Quantum Mechanics
Background:
- Understanding the electronic and vibrational structure of small carbon-chain molecules like C6H and C6D is crucial for astrochemistry and combustion research.
- Previous studies have characterized some electronic transitions, but detailed analysis of vibronic hot bands and Renner-Teller effects was limited.
Purpose of the Study:
- To record and rotationally analyze the B(2)Π - X(2)Π electronic origin bands and the 11(1)(1) μ(2)Σ-μ(2)Σ vibronic hot band transitions of C6H and C6D.
- To investigate the Renner-Teller effect for the lowest bending mode (ν(11)) in these molecules.
- To determine the excitation energy of the lowest-lying 11(1) μ(2)Σ vibronic state of C6H.
Main Methods:
- Cavity ring-down spectroscopy (CRDS) in direct absorption mode.
- Recording spectra through a supersonically expanding planar plasma.
- Precise rotational analysis of recorded spectra.
Main Results:
- Accurate spectroscopic parameters were derived for both origin and hot bands of C6H and C6D.
- The Renner parameters (ε(11)), vibrational frequencies (ω(11)), and spin-orbit coupling constants (A(SO)) for the (2)Π electronic states were determined.
- The excitation energy of the lowest-lying 11(1) μ(2)Σ vibronic state of C6H was determined to be (11.0 ± 0.8) cm⁻¹.
Conclusions:
- The study provides the first detailed analysis of the 11(1)(1) μ(2)Σ-μ(2)Σ vibronic hot bands for C6H and C6D.
- The Renner-Teller analysis offers insights into the vibronic structure and spin-orbit coupling in the (2)Π electronic states.
- The determined excitation energy refines our understanding of the low-lying electronic states of C6H.
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