Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Deactivation Processes: Jablonski Diagram01:25

Deactivation Processes: Jablonski Diagram

2.3K
Luminescence, the emission of light by a substance that has absorbed energy, is a process that involves the interaction of molecules with light. The energy-level diagram, or Jablonski diagram, is a graphical representation of these interactions, illustrating the various states and transitions a molecule can undergo. In a typical Jablonski diagram, the lowest horizontal line represents the ground-state energy of the molecule, which is usually a singlet state. This state represents the energies...
2.3K
¹H NMR: Complex Splitting01:13

¹H NMR: Complex Splitting

2.2K
A proton M that is coupled to a proton X results in doublet signals for M. However, NMR-active nuclei can be simultaneously coupled to more than one nonequivalent nucleus. When M is coupled to a second proton A, such as in styrene oxide, each peak in the doublet is split into another doublet.
Splitting diagrams or splitting tree diagrams are routinely used to depict such complex couplings. While drawing splitting diagrams, the splitting with the larger coupling constant is usually applied...
2.2K
Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule01:10

Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule

3.2K
In the AX proton spin system, proton A can sense the two spin states of a coupled proton X, resulting in a doublet NMR signal with two peaks of equal (1:1) intensity. When proton A is coupled to two equivalent protons (AX2 spin system), the spin states of each X can be aligned with or against the external field, creating three possible scenarios. This results in a 1:2:1  triplet signal, where the central peak corresponds to the chemical shift of A and is twice as large or intense as the...
3.2K
Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)01:20

Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)

2.0K
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
2.0K
¹³C NMR: ¹H–¹³C Decoupling01:04

¹³C NMR: ¹H–¹³C Decoupling

2.1K
The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak splitting due to carbon-carbon spin-spin coupling is not observed in spectra. However, protons up to three sigma bonds away split the carbon signal according to the n+1 rule, resulting in complicated spectra.
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
2.1K
Chemical Ionization (CI) Mass Spectrometry01:21

Chemical Ionization (CI) Mass Spectrometry

1.7K
The molecular ion peak of a molecule in the mass spectrum provides vital information for molecular identification. However, conventional electron impact ionization can lead to the rapid dissociation of some molecular ions before they reach the detector. A milder ionization method is required to increase the lifetime of such ionized analyte molecules. Chemical ionization (CI) is a gas-phase protonation reaction useful for mass-analyzing analyte molecules that are easily protonated to yield the...
1.7K

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Photoprotection in a desert moss: dynamic excitation quenching during the hydration cycle of the Syntrichia caninervis.

Photosynthesis research·2026
Same author

Size-dependent fluorescence kinetics reveal contributions of intrinsic quenching and singlet-triplet annihilation during LHCII aggregation.

Biochimica et biophysica acta. Bioenergetics·2026
Same author

Ultrafast charge dynamics of diketopyrrolopyrrole-based terpolymers for optoelectronic applications: impact of acceptor concentrations and thermal annealing.

Nanoscale·2026
Same author

Fluorescence concentration quenching in phthalocyanine solutions: Experimental observation and theoretical insights.

The Journal of chemical physics·2026
Same author

Objective clustering protocol for single-molecule data: A lifetime vs. intensity study.

Biophysical reports·2026
Same author

Fourth-order complex time-dependent Redfield theory for absorption line shapes.

The Journal of chemical physics·2026

Related Experiment Video

Updated: Apr 7, 2026

Thermochemical Studies of NiII and ZnII Ternary Complexes Using Ion Mobility-Mass Spectrometry
16:11

Thermochemical Studies of NiII and ZnII Ternary Complexes Using Ion Mobility-Mass Spectrometry

Published on: June 8, 2022

2.9K

Singlet-triplet annihilation in single LHCII complexes.

J Michael Gruber1, Jevgenij Chmeliov, Tjaart P J Krüger

  • 1Department of Biophysics, Faculty of Sciences, Vrije Universiteit, De Boeleaan 1081, 1081HV Amsterdam, The Netherlands. j.m.gruber@vu.nl r.van.grondelle@vu.nl.

Physical Chemistry Chemical Physics : PCCP
|July 10, 2015
PubMed
Summary

Carotenoids in light harvesting complexes quench chlorophyll triplet states, preventing harmful oxygen production. A new model explains this singlet-triplet annihilation, crucial for understanding light energy transfer.

More Related Videos

Separation of Spinach Thylakoid Protein Complexes by Native Green Gel Electrophoresis and Band Characterization using Time-Correlated Single Photon Counting
08:40

Separation of Spinach Thylakoid Protein Complexes by Native Green Gel Electrophoresis and Band Characterization using Time-Correlated Single Photon Counting

Published on: February 14, 2019

8.8K
Setting Limits on Supersymmetry Using Simplified Models
07:46

Setting Limits on Supersymmetry Using Simplified Models

Published on: November 15, 2013

9.0K

Related Experiment Videos

Last Updated: Apr 7, 2026

Thermochemical Studies of NiII and ZnII Ternary Complexes Using Ion Mobility-Mass Spectrometry
16:11

Thermochemical Studies of NiII and ZnII Ternary Complexes Using Ion Mobility-Mass Spectrometry

Published on: June 8, 2022

2.9K
Separation of Spinach Thylakoid Protein Complexes by Native Green Gel Electrophoresis and Band Characterization using Time-Correlated Single Photon Counting
08:40

Separation of Spinach Thylakoid Protein Complexes by Native Green Gel Electrophoresis and Band Characterization using Time-Correlated Single Photon Counting

Published on: February 14, 2019

8.8K
Setting Limits on Supersymmetry Using Simplified Models
07:46

Setting Limits on Supersymmetry Using Simplified Models

Published on: November 15, 2013

9.0K

Area of Science:

  • Photosynthesis research
  • Biophysics
  • Photochemistry

Background:

  • Light harvesting complex II (LHCII) in plants and algae uses carotenoids (Cars) to quench chlorophyll (Chl) triplet states.
  • This process prevents the formation of damaging singlet oxygen.
  • Carotenoid triplet states can undergo singlet-triplet (S-T) annihilation, a density-dependent quenching mechanism.

Purpose of the Study:

  • Investigate the fluorescence decay kinetics of single immobilized LHCIIs.
  • Characterize the singlet-triplet (S-T) annihilation mechanism in LHCII.
  • Develop and validate a model to explain observed kinetics.

Main Methods:

  • Single-molecule fluorescence spectroscopy at room temperature.
  • Time-resolved fluorescence decay measurements.
  • Analysis using a developed stochastic model and acousto-optic modulation.

Main Results:

  • Observed a two-exponential fluorescence decay (3.5 ns and 35 ps).
  • Fast component amplitude increased with excitation intensity, indicating annihilation.
  • Identified and quantified the S-T annihilation mechanism and its parameters.

Conclusions:

  • The study successfully identified and modeled S-T annihilation in LHCII.
  • The developed stochastic model accurately describes experimental data.
  • This model can be applied to other small molecular aggregates with fast excitation equilibration.