Ultrafast nonlinear optical (NLO) properties of four novel Corroles in the visible spectral range... more Ultrafast nonlinear optical (NLO) properties of four novel Corroles in the visible spectral range (660-800 rim) were evaluated using picosecond Z-scan technique. Ultrafast excited state dynamics have also been appraised with picosecond (ps) and femtosecond (fs) degenerate pump-probe techniques using excitation wavelengths of 800 and 600 nm, respectively. The excitation by 800 nm photons resulted in two-photon absorption at adequately high peak intensities, thereby facilitating the access to higher excited states (S-n). The nonradiative relaxation mechanisms from these states, reflected in the pump-probe data, consisted of double-exponential decay with a slow component in the range of 54-277 ps and faster component in the range of 2.0 to 2.5 ps. When excited with 600 run photons (unfocused), photoinduced absorption was observed with the first excited state S-1 being populated, and as a consequence single decay was observed in the data of all molecules studied. These retrieved lifetim...
... Control of Phase Matching and Nonlinear Generation in Dense Media by Resonant Fields Surya P.... more ... Control of Phase Matching and Nonlinear Generation in Dense Media by Resonant Fields Surya P. Tewari ... have shown that in the presence of the extra resonant plane-wave field E2 (frequency ... The dispersion [ReX 1)(3co1)] and absorption [ImX_1)(3c)1)] can be varied at will by ...
Density functional theory (DFT) calculations at the B3LYP/aug-cc-pVDZ level have been performed o... more Density functional theory (DFT) calculations at the B3LYP/aug-cc-pVDZ level have been performed on the condensed polynitroazoles based on diazole and triazole skeletons. Energy of explosion (≈1.60kcal/g), density (≈1.92g/cm3), detonation velocity (≈9.30km/s), and detonation pressure (≈ 39GPa) of model molecules are found to be promising compared to the well known explosives 1,3,5-trinitro-1,3,5-triazinane (RDX), octahydro-1,3,5,7-tetranitro-l,3,5,7-tetraazocane (HMX), and 4,4′,5,5′-tetranitro-2,2′-bi-1H-imidazole (TNBI). Presumably, the relative
ABSTRACT The generation and evolution of laser induced shock waves (SWs) and the hot core plasma ... more ABSTRACT The generation and evolution of laser induced shock waves (SWs) and the hot core plasma (HCP) created by focusing 7 ns, 532 nm laser pulses in ambient air is studied using time resolved shadowgraphic imaging technique. The dynamics of rapidly expanding plasma releasing SWs into the ambient atmosphere were studied for time delays ranging from nanoseconds to milliseconds with ns temporal resolution. The SW is observed to get detached from expanding HCP at around 3μs. Though the SWs were found to expand spherically following the Sedov-Taylor theory, the rapidly expanding HCP shows asymmetric expansion during both the expansion and cooling phase similar to that of inertial cavitation bubble (CB) dynamics. The asymmetric expansion of HCP leads to oscillation of the plasma boundary, eventually leading to collapse by forming vortices formed by the interaction of ambient air.
Large picosecond nonlinearities in Ba0.5Sr0.5TiO3 thin films, grown at different temperatures in ... more Large picosecond nonlinearities in Ba0.5Sr0.5TiO3 thin films, grown at different temperatures in situ on (100) MgO substrates using rf magnetron sputtering technique, were studied using the Z-scan technique. The nonlinear absorption mechanism, studied near 800 nm using ~2 and 25 ps pulses, switched from reverse saturable absorption type in the films deposited at temperature600 °C. The magnitude of the 3PA
Abstract We present our results from the measurements of Supereonlinuum emission (SCE) resulting ... more Abstract We present our results from the measurements of Supereonlinuum emission (SCE) resulting from the propagation ol''tightly foe used 40 femtosecond laser pulses through distilled water. The e fleet of linearly polarized (LP) and circularly polarized (CP) light pulses on the SCE: in different external focal geometries (f/6 & f/12) is studied in detail. A considerable shift in the minimum wavelength of SCF under tighter focusing limit is observed.
Herein we present some of our initial experimental results obtained from the laser induced breakd... more Herein we present some of our initial experimental results obtained from the laser induced breakdown spectroscopic (LIBS) measurements of RDX and HMX using nanosecond (ns), picosecond (ps), and femtosecond (fs) laser pulses acquired without gating and delay. RDX and HMX were mixed with KBr and pellets were prepared for the spectroscopic studies. Nanosecond pulses at 532 nm, ps/fs pulses at
Ultrafast nonlinear optical (NLO) properties of four novel Corroles in the visible spectral range... more Ultrafast nonlinear optical (NLO) properties of four novel Corroles in the visible spectral range (660-800 rim) were evaluated using picosecond Z-scan technique. Ultrafast excited state dynamics have also been appraised with picosecond (ps) and femtosecond (fs) degenerate pump-probe techniques using excitation wavelengths of 800 and 600 nm, respectively. The excitation by 800 nm photons resulted in two-photon absorption at adequately high peak intensities, thereby facilitating the access to higher excited states (S-n). The nonradiative relaxation mechanisms from these states, reflected in the pump-probe data, consisted of double-exponential decay with a slow component in the range of 54-277 ps and faster component in the range of 2.0 to 2.5 ps. When excited with 600 run photons (unfocused), photoinduced absorption was observed with the first excited state S-1 being populated, and as a consequence single decay was observed in the data of all molecules studied. These retrieved lifetim...
... Control of Phase Matching and Nonlinear Generation in Dense Media by Resonant Fields Surya P.... more ... Control of Phase Matching and Nonlinear Generation in Dense Media by Resonant Fields Surya P. Tewari ... have shown that in the presence of the extra resonant plane-wave field E2 (frequency ... The dispersion [ReX 1)(3co1)] and absorption [ImX_1)(3c)1)] can be varied at will by ...
Density functional theory (DFT) calculations at the B3LYP/aug-cc-pVDZ level have been performed o... more Density functional theory (DFT) calculations at the B3LYP/aug-cc-pVDZ level have been performed on the condensed polynitroazoles based on diazole and triazole skeletons. Energy of explosion (≈1.60kcal/g), density (≈1.92g/cm3), detonation velocity (≈9.30km/s), and detonation pressure (≈ 39GPa) of model molecules are found to be promising compared to the well known explosives 1,3,5-trinitro-1,3,5-triazinane (RDX), octahydro-1,3,5,7-tetranitro-l,3,5,7-tetraazocane (HMX), and 4,4′,5,5′-tetranitro-2,2′-bi-1H-imidazole (TNBI). Presumably, the relative
ABSTRACT The generation and evolution of laser induced shock waves (SWs) and the hot core plasma ... more ABSTRACT The generation and evolution of laser induced shock waves (SWs) and the hot core plasma (HCP) created by focusing 7 ns, 532 nm laser pulses in ambient air is studied using time resolved shadowgraphic imaging technique. The dynamics of rapidly expanding plasma releasing SWs into the ambient atmosphere were studied for time delays ranging from nanoseconds to milliseconds with ns temporal resolution. The SW is observed to get detached from expanding HCP at around 3μs. Though the SWs were found to expand spherically following the Sedov-Taylor theory, the rapidly expanding HCP shows asymmetric expansion during both the expansion and cooling phase similar to that of inertial cavitation bubble (CB) dynamics. The asymmetric expansion of HCP leads to oscillation of the plasma boundary, eventually leading to collapse by forming vortices formed by the interaction of ambient air.
Large picosecond nonlinearities in Ba0.5Sr0.5TiO3 thin films, grown at different temperatures in ... more Large picosecond nonlinearities in Ba0.5Sr0.5TiO3 thin films, grown at different temperatures in situ on (100) MgO substrates using rf magnetron sputtering technique, were studied using the Z-scan technique. The nonlinear absorption mechanism, studied near 800 nm using ~2 and 25 ps pulses, switched from reverse saturable absorption type in the films deposited at temperature600 °C. The magnitude of the 3PA
Abstract We present our results from the measurements of Supereonlinuum emission (SCE) resulting ... more Abstract We present our results from the measurements of Supereonlinuum emission (SCE) resulting from the propagation ol''tightly foe used 40 femtosecond laser pulses through distilled water. The e fleet of linearly polarized (LP) and circularly polarized (CP) light pulses on the SCE: in different external focal geometries (f/6 & f/12) is studied in detail. A considerable shift in the minimum wavelength of SCF under tighter focusing limit is observed.
Herein we present some of our initial experimental results obtained from the laser induced breakd... more Herein we present some of our initial experimental results obtained from the laser induced breakdown spectroscopic (LIBS) measurements of RDX and HMX using nanosecond (ns), picosecond (ps), and femtosecond (fs) laser pulses acquired without gating and delay. RDX and HMX were mixed with KBr and pellets were prepared for the spectroscopic studies. Nanosecond pulses at 532 nm, ps/fs pulses at
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