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Density functional calculations for the structure and magnetic parameters of the perfluorinated ethyl and n-propyl radicals are described. It is seen that fluorine substitution leads not only to nonplanarity at the radical center but to delocalization of spin density onto the [F.sup.alpha] atoms and to spin polarization effects that lead to anomalies.

An analytical potential energy surface (PES-2006) was developed and quasi-classical trajectory (QCT) calculations were used to analyze the F + C[D.sub.4] gas-phase abstraction reaction. The state-specific scattering distributions at different collision energies were found to reproduce the experimental behavior with a clear propensity toward forward scattering.

Vertical excitation energies of the C[F.sub.3]Cl molecule are determined from a response function approach with a coupled cluster (CC) reference function in order to examine the absolute photoabsorption oscillator strengths in the molecular-adapted quantum defect orbital formalism (MQDO). The results for the molecular Rydberg transitions have provided better f-values of the isolated Cl atom than the MQDO results.

The systematic investigation of in-plane hydrogen-bonded complexes of ammonia with partially substituted fluorobenzenes has shown that fluorobenzene, difluorobenzene and trifluorobenzene have favored the formation of cyclic complexes with a C-H...N-H...F-C binding motif. The tendency with which fluorobenzenes adapt to the C-H...N-H...F-C binding motif has decreased with the progressive fluorination of the benzene ring and has disappeared completely when benzene ring is substituted with five or more fluorine atoms.

Ab initio quantum chemistry calculations of the decarbonylation kinetics of [C.sub.n][F.sub.2n+1]CO radicals are reported. The results have shown that [C.sub.n][F.sub.2n+1]CO radicals have a strong tendency to decompose in order to give [C.sub.n][F.sub.2n+1] and CO under atmospheric conditions.

The chemical activation techniques coupled with electronic structure calculations were used to investigate the unimolecular reactions of a series of chlorofluoropropane molecules. Fully halogenated fluorochloroethanes and propanes seem to have high threshold energies for ClF interchange, and other decomposition pathways are favored over ClF interchange.

The structure, spectra, and rearrangement mechanisms of P[H.sub.2][F.sub.3], the first member of the P[H.sub.n][F.sub.5-n] series and a prototype for molecules that undergo rotational isomerism, are analyzed. The results have identified the spectral fingerprints that could distinguish various rotational isomers that could form a powerful basis for the characterization of various rotational isomers of P[H.sub.2][F.sub.3] when used along with high resolution measurements.

The structures, electron ionization and excitation energies and electron density distribution of symmetrical five-membered heterocycle derivatives of carbazole and fluorene are analyzed. The results have shown that the properties of consecutive oligomers have indicated their fast convergence to values characterizing polymers.

Experimental vibrational spectroscopy in conjunction with DFT quantum chemical calculations is applied to characterize two fluorofullerenes, C60F48 and C60F36. The study reveals that vibrational spectroscopy, supplemented with reliable theoretical modeling could provide a powerful structural tool to meet the challenges of the structure determination for fullerene derivatives when other method, such as X-ray or NMR are unable to provide unambiguous solutions to the problem.

An investigation is conducted of the heterogenous uptake of 8-2 fluorotelomer alcohol (FTOH) on liquid water surfaces and on 1-octanol surfaces with a droplet of train flow reactor. The larger uptake coefficient measured for 1-octanol surfaces indicates that FTOH partitioning to organic-containing cloud/fog droplets and aerosol particles may be an atmospheric loss mechanism.

Fluorescence excitation, multiphoton ionization and dispersed fluorescence spectra of bare and hydrogen-bonded 2-fluoropyridine with water are calculated in a supersonic free jet. The appearance of low frequency vibronic bands, which are seen for bare 2-fluoropyridine, is attributed to the existence of closely lying (n,pi(super star)) state.

An investigation is conducted of the relative importance of hydrogen bonding versus pie stacking interactions in DNA where the hydrogen-bonded complexes of the nucleobase mimic 2-pyridone (2PY) with seven different fluorinated benzenes. Ab initio studies are performed on the individual hydrogen bonds occurring between nucleobases and fluronated isomers.

A study conducted on modified DNA oligomers and polymerase reactions have demonstrated that canonical nucleobases can exhibit stable and even selective pairing with shape-complementary fluorobenzene nucleotides. Hydrogen bonds are believed to be absent because of the fluorination of the pairing edges and the local DNA stability is attributed pie-stacking and shape complementarity.

The ARS-E model was used for calculating the intermolecular interaction energy of hexafluorobenzene-benzene. The largest and most negative energy of -5.38 kcal/mol was observed in the slipped-parallel complex.

The collective electronic oscillator (CEO) approach was adopted for calculating the linear absorption and florescence spectra and the oscillator strengths of 2,2',7,7'-tetraphenyl-9,9'-spirobifluorene, 2,2',7,7'-tetrakis(biphenyl-4-yl)-9,9'-spirobifluorene and 2,2',7,7'-tetrakis(9,9'-spirobifluoren-2-yl)-9,9'spirobifluorene. The higher CEO modes with significant oscillator strengths are corresponding to different spiro-centers, intra-branch and inter-branch neutral electronic delocalization.

Quantum scattering calculations for the reaction F + HCI --> HF + CI are performed on ab initio potential energy surface. The shape of the adiabatic potential surface yields to a simple and intuitive interpretation for the rotational enhancement of the rate.

Hydrolysis and condensation of simple trifluorosilanes, HSiF(sub 3) and MeSiF(sub 3), is studied by quantum mechanical methods. The results suggest that the activation energy for hydrolysis by a water dimer is significantly lower than that for hydrolysis by a water monomer.

The study of ionization and double ionization spectra of (H(sub 2)O)(sub1-3)F(super -) calculated by ab initio methods with microsolvation of F(super -) is conducted. Results show that the ionization spectrum of the isomer A with C(sub 3) symmetric ground-state geometry is rather similar from the energetical point of view to that of the isomer B with one H-donor-bound second solvation shell water molecule.

The dynamics of the photoinduced reaction producing electronically excited CaF when 1:1 Ca.CH(sub 3)F complexes are deposited at the surface of large argon clusters are examined using the 'cluster isolated chemical reactions' technique. The observations suggest that a profound alteration of the calcium electronic structure and a control of the reaction by the CF stretch in CH(sub 3)F.

The 1(super 2)A', 1(super 2)A', 2(super 2)A', 2(super 2)A', and 3(super 2)A' states of the CH3F(super +) ion are studied. The 1(super 2)A' state is predicted to be the ground state, and the C(sub s)-state energy levels are different from those of the CH3F(super +) ion.

The ubiquity of the fluorine-fluorine bonding interaction for a systematic examination is reported. Teh bond path is shown to persist for a range of internuclear distances (2.3-2.8 angstrom) and a range of relative orientations of the two C-F internuclear axes.

The infrared and ultraviolet-visible absorption cross sections, effective quantum yield of photolysis, and OH, Cl, and NO(sub 3) reaction rate coefficients of CHF(sub 2)CHO are reported. The photolysis of CHF(sub 2)CHO was investigated under pseudonatural tropospheric conditions and an effective quantum yield of photolysis equal to 0.30 plusmn 0.05 over the wavelength range 290-500 nm was extracted.

A study of the dynamics and kinetics of reactions between ions of known recombination energy and CHCl(sub 2)F, CHCIF(sub 2) and CH(sub 2)CIF using the well-established selected ion flow tube (SHIFT) technique is presented. It is concluded that the H(sub 3)O(super +) ion only reacts with CHCl(sub 2)F, even though all of the observed channels are apparently endothermic.

An investigation of the mid-infrared spectra of mixed solutions in liquid xenon containing fluoroform and either ammonia or pyridine is conducted at temperatures between 173 and 213 K. For both Lewis bases, a new band is found in the CH stretching region at a frequency 5 cm(super -1) higher than that of monomer fluoroform, which is assigned to a complex between fluoroform and the Lewis base.

The improved synthetic and isolation procedures are developed that resulted in the preparation of pure C(sub 60)F(sub 20) in sufficient amounts for comprehensive vibrational spectroscopic studies. The results provide a vibrational assignment for the original conjecture of the C(sub 60)F(sub 20) structure with the equatorial belt of 20 fluorine atoms on C(sub 60) cage.

Ab initio electronic structure calculations provide potential energy surfaces for the decomposition of CF(sub 3)CFHO and its competing reaction with O(sub 2). The study indicates that the reaction of CF(sub 3)CFHO with O(sub 2) occurs by means of transition states very similar to those of the reaction of CH(sub 3)CH(sub 2)O with O(sub 2).

Chlorine atom-initiated oxidation of CF(sub 3)CFHCF(sub 2)OCF(sub 3) and CF(sub 3)CFHCF(sub 2)OCF2H gives CF3C(O)F in molar yields. The 100-year time horizon global warming potentials of CF(sub 3)CFHCF(sub 2)OCF(sub 3) and CF(sub 3)CFHCF(sub 2)OCF2H relative to CO2 are 4530 and 4340.

Fluorine radicals are generated from NF3 or F2 in microwave-generated and low-frequency (LF)-generated plasmas and are passed through flow tubes under various flow, pressure and dilution conditions. The F relative concentration decreases from ~80 percent to ~20 percent, and the F2 relative concentration increases from ~20 percent to ~80 percent, as the pressure is varied over the range 0.5-10 Torr.

Kohn-Sham solutions are constructed from ab initio densities obtained with multireference configuration interaction (MRCI) calculations for the transition state (TS) and for the intermediate complex (IC) of a prototype symmetrical reaction. The generalized approximations (GGAs) overestimate the relative stability of the systems in the experiment.

The pump-probe spectroscopy was used to investigate the primary photoreactions of 3',5'-dimethoxybenzoin (DMB) acetate and fluoride following photoexcitation by a subpicosecond laser flash. The findings reveal that DMB is an excellent protecting group for the investigation of flash processes such as protein folding.

The [S.sub.1]-[S.sub.0] limiting anisotropy of rhodamine 101 is accurately determined by using time-resolved and steady-state fluorescence measurements. The limiting anisotropy of rhodamine 101 is equal to the theoretical one-photon fundamental anisotropy and it can be used as a standard for fluorescence polarization measurements.

The time-resolved Raman spectroscopy is used to study the hydrogen-abstraction reaction of decafluorobenzophenone (DFBP) from 2-propanol in temperatures ranging from room to supercritical temperature (520 K) at 31 MPa. The vibrational frequencies of the C=C stretching modes which decrease with increasing temperature reflect the decrease in the repulsive effect due to the decrease of the packing fraction.

Electronic spectroscopy is used for studying the polycyclic hydrocarbons containing a five-member ring and their van der Waals complexes with argon and oxygen are studied with a molecular beam superfluid helium nanodroplet spectrometer. The van der Waals complexes of fluoranthene have displayed more peaks.

Several spectroscopic studies are conducted to explain the interplay between the on-chain keto defect and the interchain interaction its impact on the green and blue emission of polyflourene (PF). The analysis reveals that the interaction leads to severe color degradation, which then minimizes the green emission.

The pressure dependence of recombination reaction between Cl + FC(O)O + M --> FC(O)OCl + M is investigated at 296 K. It is determined that the reactions are expected to have a negligible impact on stratospheric ozone levels.

Multireference configuration interaction with singles and doubles (MR-CISD) calculations is performed for the optimization of conical intersections and stationary points on the fluoroethylene excited-state energy surfaces. The photodynamics of the system is discussed based on topological features of these reactions.

The reaction between the fluoride ion and chloroethane are analyzed using ab initio molecular dynamics. Some insight into the branching ratio as a function of the temperature is obtained by analyzing impact trajectories.