Restricted Hartree–Fock 6-31G calculations of electrical and mechanical anharmonicity contributions to the longitudinal vibrational second hyperpolarizability have been carried out for eight homologous series of conjugated oligomers—polyacetylene, polyyne, polydiacetylene, polybutatriene, polycumulene, polysilane, polymethineimine, and polypyrrole. To draw conclusions about the limiting infinit...

Vibrational spectral analysis of the non-linear optical (NLO) material, 2,6-dichloro-4-nitroaniline (DCNA) has been carried out by using FT-IR and FT-Raman spectroscopic techniques. The Hartree-Fock(HF) and Density Functional Theoretical (DFT) computations have been performed at 6-311++G** level to derive equilibrium geometry, vibrational wavenumbers, intensities and first order hyperpolarizabi...

The ground state geometrical energy, dipole moment, polarizability and first static hyperpolarizability of para-nitroaniline (PNA), 2-methyl-4-nitroaniline (MNA), N-methyl-4-nitroaniline (HMNA), N-methyl-2-methyl-4-nitroaniline (HMMNA), 4nitrodimethylaniline (NDMA) and N-(4-nitrophenyl)-N-methylaminoacetonitrile (NPAN) has been investigated by density functional theory (DFT) using B3LYP/6-311G*...

Vibrationally resonant sum frequency generation (VR-SFG) has been used to study the absolute molecular orientational distribution of the pendant phenyl groups at the free surface of polystyrene (PS) thin films on oxidized Si substrates. Characterization of the dependence of the VR-SFG on film thickness allows unique identification of the origin of the signal, e.g., free surface, bulk, or buried...

The first hyperpolarizabilities ?HRS of substituted hexatriene molecules have been carried out to assess the effects bridge length, frequency dispersion as well solvent polarity. These calculations confirm particular behaviour hyperpolarizability ?HRS, depolarization ratio and anisotropy factor a function incident light impact expanding ?-conjugated limit improve .Finally, interplay between ?//...

Electrooptical devices and optical communications need compounds with second-order nonlinear (NLO) properties as construction blocks. Typically, to show a large quadratic hyperpolarizability, compound should be asymmetric, characterized by variation between the dipole moments in excited ground states, have low energy electronic transitions. For example, hyperpolarizability can reached when an e...

The possibility of obtaining metal cluster (M3O(+), M = Li, Na, K) supported pristine, B-doped and BN-doped graphene nanoflakes (GR, BGR and BNGR, respectively) has been investigated by carrying out density functional theory (DFT) based calculations. Thermochemical analysis reveals the good stability of M3O(+)@GR/BGR/BNGR moieties. The dynamic stability of M3O(+)@GR/BGR/BNGR moieties is confirm...

The gas-phase thermal tautomerization reaction between 2-hydroxypyridine (2-HPY) and 2-pyridone (2-PY) was investigated by applying 6-311++G** and aug-cc-pvdz basis sets incorporated into some density functional theory (DFT) and coupled cluster with singles and doubles (CCSD) methods. The geometrical structures, dipole moments, HOMO-LUMO energy gaps, total hyperpolarizability, kinetics and ther...

We present an experimental and theoretical investigation into the coupling of C-O stretch vibrations of CO molecules adsorbed on Ru~001!. We employ surface infrared-visible ~IR-VIS! ~IV! and infrared-infraredvisible ~IR-IR-VIS! ~IIV! sum-frequency generation ~SFG! ~IV-SFG and IIV-SFG, respectively! to investigate the effects of the intermolecular coupling through the nonlinear optical response ...

We demonstrate that the tuning of the light emission from red to blue in dihydrolipoic acid (DHLA) capped Ag29 nanoclusters can be trigged with one and two photon excitations. The cluster stoichiometry was determined with mass spectrometry and found to be Ag29(DHLA)12. In a detailed optical investigation, we show that these silver nanoclusters exhibit a strong red photoluminescence visible to t...