Related Experiment Video
Updated: Jul 8, 2026
11:33
All-electronic Nanosecond-resolved Scanning Tunneling Microscopy: Facilitating the Investigation of Single Dopant Charge Dynamics
Published on: January 19, 2018
Ultrafast intersystem crossing in 1-nitronaphthalene. An experimental and computational study
Jimena S Zugazagoitia1, César Xavier Almora-Díaz, Jorge Peon
1Universidad Nacional Autónoma de México, Instituto de Química, Ciudad Universitaria, 04510, México, D.F., México.
The Journal of Physical Chemistry. A
|January 2, 2008
Summary
1-nitronaphthalene exhibits the fastest spin state change in organic compounds, with its S1 state decaying in 100 femtoseconds or less. This rapid intersystem crossing is influenced by solvent properties and explained by theoretical calculations.
Area of Science:
- Photochemistry
- Physical Chemistry
- Organic Chemistry
Background:
- The primary decay pathway for 1-nitronaphthalene's first singlet excited state (S1) is intersystem crossing to the triplet manifold.
- Understanding the timescale of this multiplicity change is crucial for photophysical studies.
Purpose of the Study:
- To determine the decay time of the S1 state of 1-nitronaphthalene in various solvents.
- To investigate the influence of solvent polarity and hydrogen-bonding ability on the multiplicity change timescale.
- To elucidate the photophysical mechanisms governing this process.
Main Methods:
- Femtosecond frequency up-conversion technique to monitor weak spontaneous molecular emission.
- Experimental measurements in diverse solvent environments.
- Time-Dependent Density Functional Theory (TD-DFT) calculations with PCM solvation model.
Main Results:
- The S1 lifetime of 1-nitronaphthalene was found to be 100 femtoseconds or less across all tested environments.
- This represents the fastest spin multiplicity change ever recorded for an organic compound.
- Bathochromic shifts in the absorption band indicate changes in singlet and triplet manifold energies, affecting fluorescence lifetime.
Conclusions:
- The S1 state dynamics in 1-nitronaphthalene exemplify El-Sayed's rules, with rapid spin state changes.
- The presence of upper triplet states, nearly isoenergetic with S1 and possessing partial (n-pi*) character, facilitates this efficient photophysical pathway.
- Solvent environment significantly influences the observed photophysical properties.
More Related Videos
Related Concept Videos
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
01:06Nuclear Overhauser Enhancement (NOE)
Irradiation of a spin-active nucleus causes an increase or decrease in the signal intensity of neighboring nuclei that are not necessarily chemically bonded or involved in J-coupling. This phenomenon, called the nuclear Overhauser enhancement (NOE), results from through-space interactions between the nuclear spins. The NOE effect decreases with increasing internuclear distance and is generally not observed beyond 4 angstroms. In NOE, dipole-dipole interactions between neighboring spin-active...
01:02¹H NMR: Interpreting Distorted and Overlapping Signals
Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...
01:17Chemical Shift: Internal References and Solvent Effects
In an NMR sample, precise measurement of the absolute absorption frequencies of nuclei is difficult. A standard internal reference compound is added, and the frequency difference between the reference signal and sample signals is measured.
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...
The internal reference compound generally used in NMR spectroscopy is tetramethylsilane (TMS). TMS is preferred because it is chemically inert, soluble in NMR solvents, and easily removable. Also, the highly shielded methyl protons in TMS yield an intense...