Related Experiment Video
Updated: Jun 4, 2026
06:49
In situ Grazing Incidence Small Angle X-ray Scattering on Roll-To-Roll Coating of Organic Solar Cells with Laboratory X-ray Instrumentation
Published on: March 2, 2021
Geometry and quadratic nonlinearity of charge transfer complexes in solution using depolarized hyper-Rayleigh
Ravindra Pandey1, Sampa Ghosh, S Mukhopadhyay
1Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India.
The Journal of Chemical Physics
|February 2, 2011
Summary
Charge transfer in molecular complexes significantly boosts quadratic nonlinearity. Polarization-resolved hyper-Rayleigh scattering and calculations reveal slipped parallel stacking in methyl benzene and quinone complexes.
Area of Science:
- Nonlinear Optics
- Supramolecular Chemistry
- Computational Chemistry
Background:
- Individual molecular components exhibit minimal quadratic nonlinearity.
- Intermolecular charge transfer (CT) interactions in complexes can dramatically enhance nonlinear optical properties.
Purpose of the Study:
- To investigate large quadratic nonlinearity in 1:1 molecular complexes.
- To determine the geometry of charge transfer complexes in solution.
- To correlate experimental findings with theoretical calculations.
Main Methods:
- Utilizing polarization-resolved hyper-Rayleigh scattering (HRS) to measure macroscopic depolarization ratios.
- Performing quantum chemical calculations (single and double configuration interaction with an SCF/IEMO method) to deduce theoretical properties.
- Analyzing experimental and theoretical data to determine equilibrium molecular geometries.
Main Results:
- Observed significant enhancement of first hyperpolarizability (β(HRS)) due to intermolecular CT.
- Measured macroscopic depolarization ratios (D and D(')) and matched them with theoretical values.
- Determined the dominant equilibrium geometry of CT complexes in solution.
Conclusions:
- Polarization-resolved HRS combined with theoretical calculations effectively elucidates CT complex geometry in solution.
- Methyl benzene and quinone complexes exhibit a slipped parallel stacking arrangement.
- Complex geometries are staggered, with some showing significant twist angles up to 30°.
Related Concept Videos
01:30The Electrical Double Layer
In the region where two bulk phases meet, an intricate electric charge distribution arises due to charge transfer, ion adsorption, molecular orientation, and charge distortion. This complex distribution is commonly referred to as the electrical double layer.When a solid electrode interfaces with ions in an electrolyte solution, the speed of electron transfer dictates the rates of oxidation and reduction. The electrode acquires a charge through the escape of atoms into the solution as cations or...
01:27The Debye–Hückel Theory of Electrolyte Solutions
The Debye–Hückel theory, established by Peter Debye and Erich Hückel in 1923, is a fundamental concept in physical chemistry. It provides an understanding of the behavior of strong electrolytes in solution, particularly explaining their deviations from ideal behavior.The theory is based on Coulombic interactions (the attraction or repulsion between charged particles) between ions in solution. In an ionic solution, oppositely charged ions tend to attract each other. This means that cations...
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
01:28Debye–Huckel–Onsager Conductance Equation
The Debye-Hückel-Onsager equation is a cornerstone of physical chemistry, providing a method to determine the molar conductance (Λm) and molar conductance at infinite dilution (Λ°m) for uni-univalent electrolytes.Uni-univalent electrolytes are electrolytes that dissociate in solution to produce one cation with a +1 charge and one anion with a –1 charge per formula unit.This equation addresses two crucial phenomena: the asymmetry effect and the electrophoretic effect. According to this equation,...
01:24Electrochemical Systems
Electrochemical systems provide a fascinating insight into the dynamic interplay of charged species within various phases. One notable example is the interaction between a membrane permeable to K⁺ ions but not to Cl⁻ ions, separating an aqueous KCl solution from pure water. As K⁺ ions diffuse through the membrane, they generate net charges on each phase, leading to a potential difference between them.Similarly, when a piece of Zn is immersed in an aqueous ZnSO₄ solution, the Zn metal, composed...
01:30Electric Field of Two Equal and Opposite Charges
Atoms generally contain the same number of positively and negatively charged particles, protons, and electrons. Hence, they are electrically neutral. However, the centers of the positive and negative charges do not always coincide. In such a scenario, the electric field of an atom may not be zero.
A separation of the positive and negative charges can lead to a weak, remnant effect of the positive and negative charges. The expectation is that the more the distance between the positive and...
A separation of the positive and negative charges can lead to a weak, remnant effect of the positive and negative charges. The expectation is that the more the distance between the positive and...