Laser excitation dependent nonlinear absorption of 2-Amino 5-Nitropyridinium dihydrogen phosphate

Abstract

Laser excitation and intensity-dependent third-order nonlinear optical (NLO) absorption properties of 2-amino 5-nitropyridinium dihydrogen phosphate (2A5NPDP) in both pulsed (532?nm, 5?ns, 100 µJ) and continuous wave (532?nm, 50?mW) regime were studied by Z-scan experiment. Under CW laser excitation, 2A5NPDP exhibits saturable absorption (SA) ascribed to be of thermo-optic origin. Interestingly the sample show reverse saturable absorption (RSA) due to genuine two-photon absorption (2PA) process under nano pulsed laser excitation. Earlier thermodynamic properties such as thermal conductivity (51?W/m.K), specific heat capacity (3894?J/Kg.K) and thermal diffusivity (7.5?×?10^?6 m²/s) were estimated theoretically from the DSC curves. Thus 2A5NPDP with excellent thermal stability and high NLO coefficients can be utilized as an energy-absorbing optical limiter and saturable absorber under nano pulsed and CW green laser excitation.     

All Arbitrarily Fixed Generalized Banana Trees Are Graceful

Consider a set of caterpillars, having equal and fixed diameter, in which one of the penultimate vertices is of arbitrary degree and all the other internal vertices including the other penultimate vertex are of fixed even degree. Merge an end-vertex adjacent to the penultimate vertex of fixed even degree of each of such caterpillars together. The rooted tree thus obtained is called Arbitrarily Fixed Generalized Banana Tree. In this paper we prove that all arbitrarily fixed generalized banana trees are graceful. This would imply that “all banana trees are graceful” and “all generalized banana trees are graceful” as corollaries.     

Molecular structure, vibrational spectroscopic, first order hyperpolarizability and HOMO-LUMO studies of 7-amino-8-oxo-3-vinyl-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid

The FT-IR and FT-Raman spectra of 7-amino-8-oxo-3-vinyl-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid (7AVCA) were recorded in the region 4000-400 cm(-1) and 3500-10 cm(-1), respectively. Quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers were carried out by ab initio HF and density functional theoretical methods invoking 6-311G(d,p) basis set. The differences between the observed and scaled wavenumber values of most of the fundamentals are very small. The electric dipole moment (μ) and the first order hyperpolarizability (β0) values have been computed quantum mechanically. The calculated results show that 7AVCA may have microscopic nonlinear optical (NLO) behavior with non-zero values. A detailed interpretation of the FT-IR and FT-Raman spectra of 7AVCA is reported. The theoretical IR and Raman spectra of 7AVCA have also been constructed. The calculated HOMO and LUMO energies show that the charge transfer occurs within the molecule.     

Quantum chromodynamics: Working group report

This is the report of the QCD working group at WHEPP-6. Discussions and work on heavy ion collisions, polarized scattering, and collider phenomenology are reported.     

Search for a light neutral particle in the decay of the 3.68 MeV state in C

A search is made for a short lived neutral particle, ø, in the decay of the 3.68 MeV (3/2^-) state in ¹³C. No evidence for such a particle with a rest mass in the region of 1.7–2.0 MeV/c² is found with a limit on the branching ratio Γ _ø/Γ_γ7×10 ⁻⁵. An upper limit of 10⁻⁶ is placed for the coupling of such a particle to proton/neutron.