RELATION BETWEEN QUANTUM AND GEOMETRIC DIMENSIONALITIES IN MOLECULAR NONLINEAR OPTICS: BEYOND THE TWO-LEVEL MODEL FOR ANISOTROPIC SYSTEMS

1996 ◽  
Vol 05 (04) ◽  
pp. 671-693 ◽  
Author(s):  
S. BRASSELET ◽  
J. ZYSS
Keyword(s):  
Excited States ◽  
Second Harmonic ◽  
Three Dimensional ◽  
Wavelength Dependence ◽  
Quantum Model ◽  
Substitution Pattern ◽  
Molecular Systems ◽  
Level Model ◽  
Anisotropic Systems ◽  
Two Level Model

The nonlinear optical susceptibilities of two- or three-dimensional molecular systems exhibit variable anisotropic features depending on their structure and substitution pattern. We show that appropriate geometric (e.g. tensorial) considerations combined with an n-level quantum model (n≥3) are able to account for such nonlinear anisotropy as rigorously defined in an invariant spherical formalism by extension of classical linear anisotropy. We call on two kinds of experiments to investigate these properties: firstly, variation of the incident polarization (VIP) in harmonic light scattering (HLS) experiments is being performed to sort out individual tensorial components of the quadratic hyperpolarizability β tensor; secondly, wavelength dependence studies in coherent second harmonic generation (SHG) from poled thin film media are shown at a preliminary stage to be able to designate those excited states responsible for the nonlinear anisotropy.

Multipolar Symmetry Patterns in Molecular Nonlinear Optics

1998 ◽  
Vol 07 (03) ◽  
pp. 397-439 ◽  
Author(s):  
J. Zyss ◽  
S. Brasselet
Keyword(s):  
Nonlinear Optics ◽  
Three Dimensional ◽  
Molecular Engineering ◽  
Quantum Model ◽  
One Dimensional ◽  
Irreducible Components ◽  
Level Model ◽  
Linear Material ◽  
Two Level Model ◽  
Photoinduced Processes

Organic materials for quadratic nonlinear optics generally follow the basic pattern of strongly dipolar quasi one-dimensional intramolecular charge transfer molecules organized in macroscopic crystalline or statistical polar lattices. This restriction has been lifted by the introduction of the much broader class of multipolar materials whereby efficient two- and three-dimensional molecules can be fruitfully exploited in self assembled or externally engineered multipolar macroscopic structures. At the molecular level, polarized harmonic scattering permits to evaluate the invariant irreducible components of the molecular quadratic tensor. Its anisotropy and dispersion can be accounted for by a three-quantum model in agreement with linear spectroscopy on poled samples, whereas the validity of the two-level model is restricted to one-dimensional systems. Permanent macroscopic multipolar organization can be implemented by purely optical photoinduced processes. Adequate choice of the polarization of "write" beams permits to imprint any desired symmetry pattern onto the (non)linear material. Photonic engineering thus complements and considerably broadens the more traditional scope of molecular engineering.

Quadratic and Cubic Nonlinearities in Solution of Intramolecular Charge Transfer Aromatic Molecules A Quantum Two-Level Approach

1987 ◽  
Vol 109 ◽  
Author(s):  
M. Barzoukas ◽  
P. Fremaux ◽  
D. Josse ◽  
F. Kajzar ◽  
J. Zyss
Keyword(s):  
Charge Transfer ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Third Harmonic ◽  
One Dimensional ◽  
Aromatic Molecules ◽  
Donor Acceptor ◽  
Level Model ◽  
Quadratic And Cubic Nonlinearities ◽  
Two Level Model

ABSTRACTA two-level expression of the second-order hyperpolarizability (y) is proposed, and shown to contain a negative charge transfer (CT) contribution. Frequency dispersed measurements of the quadratic and cubic susceptibility of N-(4-nitropheny1)-L-prolinol (NPP), N-(4-nitrophenyl)-N-methylaminoacetonitrile (NPAN) and 2-(N-prolinol)-5-nitropyridine (PNP) are reported. The electric field induced second-harmonic generation (EFISH) and third-harmonic generation (THG) techniques in solution are used. A two-level model dispersion of y as from THG measurements is shown to lead to a neglegible electronic contribution to the overall EFISH nonlinearity, as compared to the orientational contribution. The theoretical β-components of these molecules, obtained consistently by finite-field and perturbational approaches, clearly confirm that the β-tensor is one-dimensional along the donor-acceptor CT axis. The off resonance quadratic polarizabilities (β) of these molecules are sequenced as follows : β(NPP)> β(PNP)> β(NPAN). However this increased efficiency is obtained at the expense of the transparency range.

A BCS-Like Approach to the Excited State in 11Li

1997 ◽  
Vol 12 (37) ◽  
pp. 2883-2888 ◽  
Author(s):  
M. Kyotoku ◽  
C. L. Lima ◽  
E. Baldini Neto ◽  
N. Teruya
Keyword(s):  
Excited State ◽  
Model Calculation ◽  
Excited States ◽  
Experimental Results ◽  
Halo Nuclei ◽  
First Excited State ◽  
Level Model ◽  
Good Agreement ◽  
Two Level Model

A modified BCS approach is used to interpret the first excited state of 11 Li halo nuclei. In this scheme, a simple two-level model calculation is performed leading to results in good agreement with the experimental results for 11 Li for both ground and first excited states. A comparison with exact and QRPA calculations is also presented.

scholarly journals Weak Interactions in Cocrystals of Isoniazid with Glycolic and Mandelic Acids

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 328
Author(s):  
Raquel Álvarez-Vidaurre ◽  
Alfonso Castiñeiras ◽  
Antonio Frontera ◽  
Isabel García-Santos ◽  
Diego M. Gil ◽  
...  
Keyword(s):  
Density Functional ◽  
Glycolic Acid ◽  
Weak Interactions ◽  
Three Dimensional ◽  
Functional Theory ◽  
Molecular Systems ◽  
X Ray Crystallography ◽  
Hydroxycarboxylic Acids ◽  
Non Covalent Interactions ◽  
Covalent Interactions

This work deals with the preparation of pyridine-3-carbohydrazide (isoniazid, inh) cocrystals with two α-hydroxycarboxylic acids. The interaction of glycolic acid (H2ga) or d,l-mandelic acid (H2ma) resulted in the formation of cocrystals or salts of composition (inh)·(H2ga) (1) and [Hinh]+[Hma]–·(H2ma) (2) when reacted with isoniazid. An N′-(propan-2-ylidene)isonicotinic hydrazide hemihydrate, (pinh)·1/2(H2O) (3), was also prepared by condensation of isoniazid with acetone in the presence of glycolic acid. These prepared compounds were well characterized by elemental analysis, and spectroscopic methods, and their three-dimensional molecular structure was determined by single crystal X-ray crystallography. Hydrogen bonds involving the carboxylic acid occur consistently with the pyridine ring N atom of the isoniazid and its derivatives. The remaining hydrogen-bonding sites on the isoniazid backbone vary based on the steric influences of the derivative group. These are contrasted in each of the molecular systems. Finally, Hirshfeld surface analysis and Density-functional theory (DFT) calculations (including NCIplot and QTAIM analyses) have been performed to further characterize and rationalize the non-covalent interactions.

Depth-of-field extension in optical imaging for rapid crystal screening

2021 ◽  
Vol 77 (4) ◽  
pp. 463-470
Author(s):  
Chen Li ◽  
Changqin Ding ◽  
Minghe Li ◽  
Jiayue Rong ◽  
Hilary Florian ◽  
...  
Keyword(s):  
Optical Imaging ◽  
Nonlinear Optical ◽  
Second Harmonic ◽  
Wavelength Dependence ◽  
Optical Microscope ◽  
Field Extension ◽  
Protein Crystal ◽  
Depth Of Field ◽  
Theoretical Predictions ◽  
Second Harmonic Generation Imaging

The depth of field (DoF) was extended 2.8-fold to achieve rapid crystal screening by retrofitting a custom-designed micro-retarder array (µRA) in the optical beam path of a nonlinear optical microscope. The merits of the proposed strategy for DoF enhancement were assessed in applications of second-harmonic generation imaging of protein crystals. It was found that DoF extension increased the number of crystals detected while simultaneously reducing the number of `z-slices' required for screening. Experimental measurements of the wavelength-dependence of the extended DoF were in excellent agreement with theoretical predictions. These results provide a simple and broadly applicable approach to increase the throughput of existing nonlinear optical imaging methods for protein crystal screening.

Numerical study of the second harmonic generation in FELs

2021 ◽  
Vol 28 (3) ◽  
Author(s):  
A. M. Kalitenko
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Free Electron ◽  
Numerical Study ◽  
Second Harmonic ◽  
Three Dimensional ◽  
X Ray ◽  
Linac Coherent Light Source ◽  
The Individual ◽  
Analytical Expressions

A numerical study of the effect of betatron oscillations on the second harmonic generation in free-electron lasers (FELs) is presented. Analytical expressions for the effective coupling strength factors are derived that clearly distinguish all contributions in subharmonics and each polarization of the radiation. A three-dimensional time-dependent numerical FEL code that takes into account the main FEL effects and the individual contribution of each electron to the second harmonic generation is presented. Also, the X- and Y-polarizations of the second harmonic are analyzed. The second harmonic was detected in experiments at the Advanced Photon Source (APS) Low Energy Undulator Test Line (LEUTL) and Linac Coherent Light Source (LCLS) in the soft X-ray regime. The approach presented in the article can be useful for a comprehensive study and diagnostics of XFELs. In the paper, the LCLS and Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL) experiments are modeled. The simulation results are in a good agreement with the experimental data.

Total reflection and canalized states in a three-dimensional quantum model of thin films

1997 ◽  
Vol 234 (4) ◽  
pp. 251-261
Author(s):  
N. Markovska ◽  
J. Pop-Jordanov ◽  
E.A. Solov'ev
Keyword(s):  
Thin Films ◽  
Three Dimensional ◽  
Total Reflection ◽  
Quantum Model
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