Related Experiment Video
Updated: Aug 6, 2026

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−
Published on: July 27, 2018
Photodissociation of thymine
Michael Schneider1, Raman Maksimenka, F Johannes Buback
1Institute of Physical Chemistry, University of Würzburg, Am Hubland, D-97074, Würzburg.
Researchers studied thymine photochemistry using advanced spectroscopy. Findings indicate hydrogen atom photofragment spectra are dominated by two-photon excitation and dissociation from a long-lived dark state, not the pisigma* state.
Area of Science:
- Photochemistry
- Molecular Dynamics
- Spectroscopy
Background:
- Thymine is a key DNA nucleobase.
- Understanding its photochemical behavior is crucial for DNA damage and repair mechanisms.
- Previous studies suggested a role for the pisigma* excited state in thymine photodissociation.
Purpose of the Study:
- To investigate the photochemistry and photodissociation dynamics of thymine.
- To elucidate the deactivation pathways of thymine following optical excitation.
- To determine the role of the pisigma* excited state in thymine photodissociation.
Main Methods:
- Two-colour photofragment Doppler spectroscopy.
- One-colour slice imaging.
- Optical excitation of thymine into the pipi* state.
Main Results:
- Hydrogen atom photofragment spectra were dominated by two-photon excitation processes.
- Dissociation occurred statistically following excitation from a long-lived dark state.
- No significant evidence for the involvement of the pisigma* excited state was observed.
Conclusions:
- Thymine photodissociation primarily proceeds via a two-photon mechanism involving a long-lived dark state.
- The previously proposed pisigma* state pathway appears to play a minor role in thymine photodissociation.
- These findings refine our understanding of thymine photochemistry and DNA photostability.
Related Concept Videos
Mutations
Chromosomal Alterations Are Large-Scale Mutations
While point mutations are changes in a single nucleotide in...
Mass Spectrometry: Aromatic Compound Fragmentation
Proofreading
Mass Spectrometry: Molecular Fragmentation Overview
One type of fragmentation pattern is the cleavage of a single bond in the molecular ion. The cleavage leads to a radical and a cation. The cleavage can occur at...
Spontaneous and Induced Mutations
DNA Base Pairing
