Studies of NMNH(2-) Conformers in Water-Methanol Solutions: Comparative Analysis of the Biexponential Fluorescence Signals for NMNH(2-) and NADH.

studies of the structure of reduced β-nicotinamide d-ribonucleotide (NMNH(2-)) conformations in water and methanol solutions have been carried out for clarifying the role of the phosphate groups in fluorescence parameters of the NMNH(2-) molecule and the reduced β-nicotinamide adenine dinucleotide (NADH) molecule. Relaxed potential energy surfaces as a function of the dihedral rotation angle of the amide group in the NMNH(2-) molecule were calculated in the ground electronic state and the first excited electronic state to better understand the effect of phosphate groups on the nonradiative decay rates in the nicotinamide chromophore groups. The differences in the weighting coefficients in the biexponential fluorescence signals for NMNH(2-) and NADH molecules in solution were explained.

Two-Photon Excited Fluorescence Dynamics in Enzyme-Bound NADH: the Heterogeneity of Fluorescence Decay Times and Anisotropic Relaxation.

The dynamics of polarized fluorescence in NADH in alcohol dehydrogenase (ADH) in buffer solution has been studied using the TCSPC spectroscopy. A global fit procedure was used for determination of the fluorescence parameters from experiment. The interpretation of the results obtained was supported by calculations of the NADH structure.

Relaxation dynamics of alkyl derivatives of fluorescein MitoFluo and C-Fl in solutions with liposomes.

We present results of experimental and theoretical studies of excited state dynamics in two alkyl derivatives of fluorescein, MitoFluo and C-Fl in solutions with liposomes. The liposomes DOPC and soybeanPC + 20% Cardiolipin (Azo-Cl), modelling cellular and inner mitochondrial membranes, respectively, were used in experiments. Both types of liposomes were shown to reduce significantly the fluorescence quantum yield as compared to that of pure fluorescein derivatives in solutions, while DOPC liposomes also caused a noticeable (ca 10 nm) red shift of fluorescence maximum.

Two-Photon Excited Fluorescence Dynamics in NADH in Water-Methanol Solutions: The Role of Conformation States.

The dynamics of polarized fluorescence in reduced nicotinamide adenine dinucleotide (NADH) at 460 nm under two-photon excitation at 720 nm by femtosecond laser pulses in water-methanol solutions has been studied experimentally and theoretically as a function of methanol concentration. A number of fluorescence parameters have been determined from experiment by means of the global fit procedure and then compared with the results reported by other authors. A comprehensive analysis of experimental errors was made.

Two-color two-photon excited fluorescence of indole: determination of wavelength-dependent molecular parameters.

We present a detailed study of two-color two-photon excited fluorescence in indole dissolved in propylene glycol. Femtosecond excitation pulses at effective wavelengths from 268 to 293.33 nm were used to populate the two lowest indole excited states (1)La and (1)Lb and polarized fluorescence was then detected.

Two-color two-photon excited fluorescence of 2-methyl-5-tert-butyl-p-quaterphenyl (DMQ): ab initio calculations and experimental determination of the molecular parameters.

The paper presents experimental and theoretical studies of two-photon excitation dynamics in 2-methyl-5-tert-butyl-p-quaterphenyl (DMQ) dissolved in cyclohexane/paraffin. Experimentally, a two-color two-photon (2C2P) excitation by two femtosecond laser pulses at 800 and 400 nm has been used in combination with the time-resolved detection of polarized molecular fluorescence. The fluorescence decay was found to be two-exponential, resulting in the molecular excited state lifetime of 753 ± 10 ps and the rotational correlation time of 724 ± 45 ps.

Photodissociation of HBr. 1. Electronic structure, photodissociation dynamics, and vector correlation coefficients.

Ab initio potential energy curves, transition dipole moments, and spin-orbit coupling matrix elements are computed for HBr. These are then used, within the framework of time-dependent quantum-mechanical wave-packet calculations, to study the photodissociation dynamics of the molecule. Total and partial integral cross sections, the branching fraction for the formation of excited-state bromine atoms Br(2P(1/2)), and the lowest order anisotropy parameters, beta, for both ground and excited-state bromine are calculated as a function of photolysis energy and compared to experimental and theoretical data determined previously.

Velocity map imaging study of BrCl photodissociation at 467 nm: determination of all odd-rank (K = 1 and 3) anisotropy parameters for the Cl(2P(3/2)0) photofragments.

Resonance-enhanced multiphoton ionization and velocity map imaging of the Cl(2P(3/2)0) fragments of BrCl photolysis at 467.16 nm have been used to obtain a complete set of orientation parameters (with ranks K = 1 and 3) describing the polarization of the electronic angular momentum. The experiments employ two geometries distinguished only by the circular or linear polarization of the photolysis laser beam.

Orbital alignment in N2O photodissociation. I. Determination of all even rank anisotropy parameters.

We present a general method for determination of the photofragment K=4 state multipoles in an ion imaging experiment. These multipoles are important for determining the full density matrix for any photofragment with j(a)> or =2. They are expressed in terms of laboratory frame anisotropy parameters that have distinct physical origins and possess characteristic angular distributions.