Search results for "nmr"

showing 5 items of 1575 documents

Molecule-like photodynamics of Au102(pMBA)44 nanocluster.

2015

Photophysical properties of a water-soluble cluster Au102(pMBA)44 (pMBA = para-mercaptobenzoic acid) are studied by ultrafast time-resolved mid-IR spectroscopy and density functional theory calculations in order to distinguish between molecular and metallic behavior. In the mid-IR transient absorption studies, visible or near-infrared light is used to electronically excite the sample, and the subsequent relaxation is monitored by studying the transient absorption of a vibrational mode in the ligands. Based on these studies, a complete picture of energy relaxation dynamics is obtained: (1) 0.5-1.5 ps electronic relaxation, (2) 6.8 ps vibrational cooling, (3) intersystem crossing from the low…

ta114ChemistryRelaxation (NMR)General EngineeringGeneral Physics and Astronomytransient absorptionInternal conversion (chemistry)PhotochemistryMolecular physicselectronic relaxationvibrational spectroscopyIntersystem crossinggold nanoclusterUltrafast laser spectroscopyGeneral Materials ScienceDensity functional theoryTriplet stateSpectroscopyGround stateta116femtosecondACS nano
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Role of Vibrational Dynamics in Electronic Relaxation of Cr(acac)3

2015

Ultrafast energy relaxation of Cr(acac)3 dissolved in tetrachloroethylene (TCE) is studied by time-resolved infrared (TRIR) spectroscopy by using electronic and vibrational excitation. After electronic excitation at 400 or 345 nm, the ground state recovers in two time scales: 15 ps (major pathway) and 800 ps (minor pathway), corresponding to fast electronic transition to the ground state and intermediate trapping on the long-lived (2)E state followed by intersystem crossing (ISC) to the ground state. The quantum yield for the fast recovery of the ground state depends on the excitation wavelength, being higher for 345 nm. Vibrational cooling (VC) occurs on the electronic excited states with …

ta114ChemistryRelaxation (NMR)kinetic modelsQuantum yieldMolecular physicsMolecular electronic transitiontransition metal complexesvibrationsIntersystem crossingComputational chemistryExcited statePhysical and Theoretical ChemistryGround stateSpectroscopyta116ExcitationThe Journal of Physical Chemistry A
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Study of the curing of a DGEBA based system through structural investigation

2011

thermal curing epoxy resins NMR spectroscopy DMTA analysisSettore CHIM/07 - Fondamenti Chimici Delle Tecnologie
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HS-SPME and GC-MS as valid tools to assess volatile organic compounds from soil natural organic matter

2008

volatile organic compounds humic acids SPMESOIL HUMIC SUBSTANCES HS-SPME NMR
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On the convergence of zero-point vibrational corrections to nuclear shieldings and shielding anisotropies towards the complete basis set limit in wat…

2016

The method and basis set dependence of zero-point vibrational corrections (ZPVCs) to nuclear magnetic resonance shielding constants and anisotropies has been investigated using water as a test system. A systematic comparison has been made using the Hartree–Fock, second-order Møller–Plesset perturbation theory (MP2), coupled cluster singles and doubles (CCSD), coupled cluster singles and doubles with perturbative triples corrections (CCSD(T)) and Kohn–Sham density functional theory with the B3LYP exchange-correlation functional methods in combination with the second-order vibrational perturbation theory (VPT2) approach for the vibrational corrections. As basis sets, the correlation consisten…

waterBiophysicsZero-point energyzero-point vibrational correctionMonotonic function010402 general chemistry01 natural sciencesQuantum mechanics0103 physical sciencesPhysics::Atomic and Molecular ClustersCCSD(T)Limit (mathematics)complete basis set limitPhysics::Chemical PhysicsPhysical and Theoretical ChemistryMolecular BiologyBasis setPhysics010304 chemical physicsBasis (linear algebra)Condensed Matter PhysicsNMR shielding constant0104 chemical sciencesCoupled clusterDensity functional theoryPerturbation theory (quantum mechanics)Molecular Physics
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